Outcomes and Complications of Halo Vest Immobilization in Adults with Cervical Spine Injuries: A 10-Year Retrospective Cohort Study In a Tertiary UK Centre

Outcomes and Complications of Halo Vest Immobilization in Adults with Cervical Spine Injuries: A 10-Year Retrospective Cohort Study In a Tertiary UK Centre | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Outcomes and Complications of Halo Vest Immobilization in Adults with Cervical Spine Injuries: A 10-Year Retrospective Cohort Study In a Tertiary UK Centre Keren Smallwood, Masna Inam, Oluwaseyi Adebola, Neil Buxton, Nisaharan Srikandarajah This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8681118/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Halo vest immobilization remains a widely utilized non-surgical treatment for cervical spine fractures. However, comprehensive data on complication rates, fusion outcomes, and factors influencing treatment success are limited, particularly regarding clinical decision-making when radiologic fusion is incomplete. Objective To evaluate complication rates, fusion outcomes, predictive factors for treatment success, and clinical decision-making patterns in adult patients undergoing halo vest immobilization for cervical spine injuries. Methods This retrospective cohort study analysed 205 adult patients (mean age 56.6 ± 16.6 years; 62.4% male) treated with halo vest immobilization for cervical spine injuries at a tertiary spine centre from 2012–2022. Patient demographics, fracture characteristics, comorbidities, smoking status, complications, and fusion outcomes were recorded. Statistical analysis included chi-square tests, Mann-Whitney U tests, and multivariable logistic regression to identify predictors of complications, fusion success, and surgical intervention. Kaplan-Meier survival analysis assessed time to fusion. Results Fracture distribution included C2 (36%), subaxial cervical spine (42%), C1/C2 combined (12%), and C1 alone (7%). Mean duration of halo immobilization was 169.9 ± 92.3 days. Complications occurred in 37.6% of patients, with pin-site infection being most common (minor: 16.1%, severe: 6.3%). Complete or partial fusion was achieved in 57.6% of patients (95% CI: 50.6–64.3%), while 26.8% showed no radiologic fusion but were deemed clinically stable for halo removal based on dynamic imaging and absence of neck pain. Younger age (41–65 years) was associated with longer immobilization duration (206 days vs. 114 days in patients > 65, p < 0.001). Smoking status showed no significant association with fusion rates (p = 0.42) but was associated with increased movement on dynamic imaging (12.3% vs. 5.7% in non-smokers, p = 0.03). The surgical conversion rate was 22.0%, with non-union (24.4% of surgical cases), progression of instability (24.4%), and infection requiring operative management (22.2%) being the primary indications. Overall mortality was 0.5% (n = 1). Conclusion Halo vest immobilization remains an effective treatment modality for cervical spine injuries in adults with acceptable complication rates and low mortality. Clinical stability assessed through dynamic flexion-extension imaging provides a safe criterion for discontinuing halo immobilization in approximately one-quarter of patients despite incomplete radiologic fusion. This finding supports a paradigm shift toward functional outcome assessment rather than strict reliance on static radiologic fusion criteria. Younger patients and those with complex fracture patterns require longer immobilization periods. Halo vest Cervical spine fracture Complications Fusion Clinical stability Dynamic imaging Figures Figure 1 Figure 2 Introduction Cervical spine fractures represent a significant clinical challenge, with management strategies ranging from conservative immobilization to complex surgical intervention [ 1 – 3 ]. Halo vest immobilization, introduced in the 1960s, has become a cornerstone non-surgical treatment modality, particularly for patients in whom surgery is contraindicated due to medical comorbidities, patient preference, or fracture patterns favourable for conservative management [ 4 , 5 ]. The halo vest provides rigid cervical immobilization through a system of skull pins attached to a vest, restricting motion across all cervical planes. This mechanical stabilization facilitates fracture healing while avoiding the risks associated with surgical intervention [ 6 , 7 ]. However, halo immobilization is associated with a distinct complication profile, including pin-site infections (reported rates 2–60%), pin loosening (5–36%), pressure ulcers, and dysphagia [ 10 – 13 ]. Understanding the balance between therapeutic efficacy and complication risk is essential for informed clinical decision-making. While numerous studies have examined complication rates and fusion outcomes following halo vest application, several important knowledge gaps persist. First, limited data exist on the decision-making process for discontinuing halo immobilization when radiologic fusion is incomplete but clinical stability is observed on dynamic imaging. Second, the factors predictive of successful fusion versus treatment failure requiring surgical conversion remain incompletely characterized. Third, contemporary large-series data from European centres are sparse, with most published series originating from North American institutions [ 14 – 16 ]. Additionally, previous literature has suggested elevated mortality rates associated with halo vest immobilization, particularly in elderly populations, ranging from 8–40% [ 17 , 18 ]. However, these figures may reflect patient selection bias rather than treatment-specific mortality, warranting re-examination with contemporary data. This study aimed to: (1) evaluate complication rates and types in a contemporary cohort of adults treated with halo vest immobilization; (2) assess radiologic fusion outcomes and clinical stability patterns; (3) identify predictive factors for complications, fusion success, and surgical conversion; and (4) examine the clinical decision-making process for discontinuing halo immobilization in the absence of complete radiologic fusion. Methods Study Design and Population This retrospective cohort study was conducted in a tertiary neurosurgical referral centre in Liverpool, United Kingdom. All adult patients (age ≥ 18 years) who underwent halo vest immobilization for cervical spine injuries between January 2012 and December 2022 were included. The study received institutional review board approval, and the need for informed consent was waived due to the retrospective nature of the analysis. Inclusion criteria comprised: (1) age ≥ 18 years; (2) cervical spine injury requiring halo vest immobilization; (3) minimum follow-up of 12 weeks or until halo removal. Exclusion criteria included: (1) incomplete medical records or imaging; (2) lost to follow-up before treatment completion; (3) prior cervical spine surgery before halo application. Data Collection Clinical and radiographic data were extracted from electronic medical records. Demographic variables included age, sex, smoking status, and documented comorbidities. Injury-related variables comprised mechanism of injury, fracture level and type (classified according to AO Spine classification where applicable), presence of neurological deficit, and indication for halo application. Treatment variables included duration of halo immobilization, use of pre-application skull traction, pin torque settings, and need for pin retorquing. Outcome variables encompassed complications (categorized and graded), radiologic fusion status (assessed by fellowship-trained neuroradiologists with spine subspecialty interest), clinical stability on dynamic imaging, and need for surgical intervention. Outcome Definitions Radiologic fusion was categorized as: (1) good fusion - complete bony bridging across fracture site with trabecular continuity; (2) partial fusion - incomplete bridging with persistent lucency but no fracture line progression; (3) no fusion - persistent fracture line without bridging bone. Clinical stability was defined as <3mm translation and < 11° angulation on flexion-extension radiographs, combined with absence of mechanical neck pain. Radiologic fusion assessment was performed using plain radiography (anteroposterior and lateral cervical spine views) at routine intervals. Computed tomography imaging was obtained in cases where plain films were inconclusive. All radiographs were formally reported by our institutional neuroradiologists and also reviewed by the consultant spine surgeon managing the patient. Dynamic imaging was primarily assessed through formal neuroradiologist reports. In cases where instability was noted or halo removal was considered despite incomplete fusion, measurements were verified by the senior spine surgeon using standardized measurement techniques to ensure consistency with established instability thresholds (< 3mm translation, < 11° angulation) [ 8 , 9 ]. Complications were recorded using a standardized classification: pin-site infection (minor: for example, superficial infection requiring oral antibiotics; severe: purulent drainage or osteomyelitis requiring IV antibiotics or surgical debridement); pin loosening (requiring unscheduled retorquing or pin repositioning); pressure ulcers (Stage II or greater); skull breach (pin penetration through inner table); dysphagia (requiring dietary modification or swallow therapy); and neurological deterioration (new or worsening motor/sensory deficit attributable to halo treatment). Halo Vest Application Protocol All halo vests were applied by consultant spine surgeons or senior specialty registrars (ST6+) under local anaesthesia. Standard pin placement sites were anterolateral (2cm above orbital rim, in line with mid-pupil) and posterolateral (diagonal from anterolateral pins). Skull pins were initially torqued to 6–8 inch-pounds using a torque screwdriver, with mean final torque 7.43 Nm for skull pins and 30 Nm for vest components. Pins were retorqued at 24–48 hours and weekly thereafter for the first month, then as clinically indicated. Pin sites were cleaned twice daily with normal saline or chlorhexidine solution. Follow-up and Halo Removal Criteria Patients underwent clinical and radiographic assessment at 2-week intervals for the first 6 weeks, then monthly. Static cervical spine radiographs were obtained at each visit. At 12 weeks, patients without evidence of radiologic fusion underwent flexion-extension radiography to assess clinical stability. Halo removal was considered when either: (1) radiologic fusion was achieved (good or partial fusion with no movement on dynamic imaging), or (2) clinical stability was demonstrated on flexion-extension views with absence of mechanical neck pain, regardless of fusion status. Patients with persistent instability on dynamic imaging continued halo immobilization with reassessment at 4-week intervals. Surgical intervention was considered for: (1) progressive instability, (2) non-union at 6 months, (3) neurological deterioration, (4) treatment failure with recurrent fracture displacement, or (5) patient intolerance necessitating alternative management. Statistical Analysis Descriptive statistics were reported as mean ± standard deviation for normally distributed continuous variables, median (interquartile range) for non-normally distributed data, and frequencies (percentages) for categorical variables. Normal distribution was assessed using Shapiro-Wilk test and visual inspection of Q-Q plots. Univariate comparisons employed chi-square test or Fisher's exact test (for expected cell counts < 5) for categorical variables, and independent t-test or Mann-Whitney U test for continuous variables, depending on distribution. Kaplan-Meier survival analysis was used to estimate time to radiologic fusion, with log-rank test comparing fusion rates between subgroups. Multivariable logistic regression models were constructed to identify independent predictors of: (1) any complication, (2) fusion success (good or partial fusion), and (3) surgical conversion. Variables with p < 0.10 in univariate analysis were entered into multivariable models. Model fit was assessed using Hosmer-Lemeshow goodness-of-fit test, and discriminative ability using area under the receiver operating characteristic curve (AUC-ROC). Results were reported as odds ratios (OR) with 95% confidence intervals (CI). All statistical tests were two-sided, with p < 0.05 considered statistically significant. Statistical analysis was performed using SPSS version 28.0 (IBM Corp., Armonk, NY, USA) and R version 4.2.0 (R Foundation for Statistical Computing, Vienna, Austria). Results Patient Demographics and Injury Characteristics A total of 205 adult patients met inclusion criteria. Baseline demographic and injury characteristics are presented in Table 1 . Mean age was 56.6 ± 16.6 years (median 59 years, range 18–92), with male predominance (62.4%, n = 128). The cohort demonstrated significant age-related heterogeneity: 18.0% (n = 37) aged 16–40 years, 47.8% (n = 98) aged 41–65 years, and 34.6% (n = 71) aged > 65 years. Documented comorbidities were present in 78.5% of patients (n = 161). Current smoking was reported in 27.8% (n = 57), with 60.5% (n = 124) non-smokers and 11.7% (n = 24) unknown status. The primary indication for halo vest immobilization was traumatic fracture in 80.0% of patients (n = 164), followed by infection/osteomyelitis (6.8%, n = 14), metastatic disease (5.9%, n = 12), and atlantoaxial subluxation (1.5%, n = 3). Among traumatic fractures, the anatomic distribution was: C2 fractures (36.0%, n = 74), subaxial cervical spine and upper thoracic (C3-T3) fractures (42.0%, n = 87), combined C1/C2 fractures (12.0%, n = 24), and isolated C1 fractures (7.0%, n = 15). Falls represented the predominant mechanism (58.0%, n = 119), followed by road traffic collision (11.2%, n = 23), infection-related vertebral instability (7.8%, n = 16), and metastatic disease (4.9%, n = 10). Among fracture patients, 72.6% (n = 119/164) sustained injury from falls. Neurological deficit at presentation was documented in 22.4% (n = 46) of patients. Table 1 Baseline Demographics and Injury Characteristics (N = 205) Characteristic Value Demographics Age (years), mean ± SD 56.6 ± 16.6 Age (years), median (range) 59 (18–92) Male sex, n (%) 128 (62.4%) Female sex, n (%) 77 (37.6%) Age Distribution 16–40 years, n (%) 37 (18.0%) 41–65 years, n (%) 98 (47.8%) > 65 years, n (%) 71 (34.6%) Risk Factors Current smoker, n (%) 57 (27.8%) Non-smoker, n (%) 124 (60.5%) Smoking status unknown, n (%) 24 (11.7%) Documented comorbidities, n (%) 161 (78.5%) Primary Indication for Halo Traumatic fracture, n (%) 164 (80.0%) Infection/osteomyelitis, n (%) 14 (6.8%) Metastatic disease, n (%) 12 (5.9%) Atlantoaxial subluxation, n (%) 3 (1.5%) Other, n (%) 12 (5.9%) Fracture Level Distribution C1 alone, n (%) 15 (7.3%) C2 alone, n (%) 74 (36.1%) C1/C2 combined, n (%) 24 (11.7%) Subaxial (C3-T3), n (%) 87 (42.4%) Mechanism of Injury Fall, n (%) 119 (58.0%) Road traffic collision, n (%) 23 (11.2%) Infection-related, n (%) 16 (7.8%) Metastatic disease, n (%) 10 (4.9%) Other/multiple, n (%) 37 (18.0%) Neurological Status Any neurological deficit, n (%) 46 (22.4%) Neurologically intact, n (%) 158 (77.1%) SD standard deviation Table 2 Treatment Characteristics and Outcomes by Age Group Variable 16–40 years (n = 37) 41–65 years (n = 98) > 65 years (n = 71) P-value Age, mean ± SD 28.7 ± 6.5 55.2 ± 6.8 73.2 ± 4.8 < 0.001 Male, n (%) 26 (70.3%) 60 (61.2%) 43 (60.6%) 0.54 Current smoker, n (%) 10 (27.0%) 36 (36.7%) 11 (15.5%) 0.006 Treatment Duration Halo duration (days), mean ± SD 183 ± 89 206 ± 97 114 ± 76 < 0.001 Hospital LOS (days), mean ± SD 16 ± 12 26 ± 19 24 ± 20 0.02 Pre-application traction, n (%) 8 (21.6%) 20 (20.4%) 8 (11.3%) 0.18 Complications Any complication, n (%) 9 (24.3%) 34 (34.7%) 25 (35.2%) 0.36 Pin-site infection, n (%) 9 (24.3%) 11 (11.2%) 13 (18.3%) 0.52 Skull breach, n (%) 0 (0%) 3 (3.1%) 4 (5.6%) 0.04 Surgical Conversion Surgical intervention, n (%) 9 (24.3%) 27 (27.6%) 9 (12.7%) 0.04 SD = standard deviation; LOS = length of stay. P-values from ANOVA for continuous variables, chi-square test for categorical variables. Mean duration of halo vest immobilization was 169.9 ± 92.3 days (median 167 days, range 14–458 days), with significant age-dependent variation (Table 2 ). The 41–65 age group demonstrated longest immobilization duration (206 ± 97 days) compared to 16–40 years (183 ± 89 days) and > 65 years (114 ± 76 days; p < 0.001 by ANOVA). Mean hospital length of stay for initial halo application was 23.1 ± 18.7 days. Pre-application skull traction was utilized in 17.6% (n = 36) of patients. Table 3 Complications by Type and Severity Complication Type Number Percentage No complications 128 62.4% Any complication 77 37.6% Specific Complications Pin-site infection (total) 46 22.4% Minor (oral antibiotics) 33 16.1% Severe (IV antibiotics/surgery) 13 6.3% Skull breach 7 3.4% Loose pins 7 3.4% Neck pain 5 2.4% Non-union 4 2.0% Pressure ulcer/sore 3 1.5% Spinal deformity 2 1.0% Failed treatment 2 1.0% Respiratory issues 1 0.5% Neurological deterioration 0 0% Dysphagia 0 0% Headache (requiring intervention) 0 0% Some patients experienced multiple complications. IV intravenous Overall complication rate was 37.6% (n = 77 patients), with 62.4% (n = 128) experiencing no complications (Table 3 ). The most common complication was pin-site infection, occurring in 22.4% of patients (n = 46): minor infection requiring oral antibiotics in 16.1% (n = 33) and severe infection necessitating intravenous antibiotics or surgical debridement in 6.3% (n = 13). Skull breach from pin penetration occurred in 3.4% (n = 7), loose pins requiring unscheduled intervention in 3.4% (n = 7), and pressure ulcers in 1.5% (n = 3). Notably, no patients experienced new or worsening neurological deficit attributable to halo treatment, and no cases of dysphagia or symptomatic headache were documented. Age-stratified analysis revealed highest complication rate in the 41–65 age group (34.7%, n = 34/98) compared to 16–40 years (24.3%, n = 9/37) and > 65 years (35.2%, n = 25/71), though differences were not statistically significant (p = 0.36, chi-square test). Pin-site infection rates were comparable across age groups (p = 0.52), but skull breach was more common in elderly patients (5.6% in > 65 vs. 2.0% in younger groups, p = 0.04). Table 4 Fusion Outcomes and Indications for Surgical Intervention A. Fusion Outcomes (N = 205) Outcome n (%) Good fusion 63 (30.7%) Partial fusion 55 (26.8%) No fusion 55 (26.8%) Not applicable* 31 (15.1%) Unknown/incomplete imaging 1 (0.5%) Combined good/partial fusion 118 (57.6%) Dynamic Imaging Results (n = 155 evaluable) No movement on flexion-extension 137 (88.4%) Movement within acceptable limits 16 (10.3%) Excessive movement 2 (1.3%) Clinical Stability Without Radiologic Fusion Patients with no radiologic fusion 55 Achieved clinical stability 55 (100%) Required subsequent surgery 0 (0%) Overall successful stabilization† 173 (84.4%) B. Surgical Intervention (n = 45, 22.0%) Indication n (% of surgical cases) Non-union 11 (24.4%) Progressive instability 11 (24.4%) Infection requiring operative management 10 (22.2%) Post-halo elective augmentation 7 (15.6%) Diagnostic followed by stabilization 4 (8.9%) Other indications 10 (22.2%) Mean time to surgery, weeks ± SD 14.3 ± 8.9 *Not applicable: metastatic disease, infection, early mortality, or non-fracture indication where fusion assessment not relevant. †Denominator excludes 'not applicable' cases. SD standard deviation Fusion assessment was applicable in 174 patients (84.9%), with 31 patients (15.1%) classified as not applicable (predominantly metastatic disease, infection, or mortality before fusion assessment). Among evaluable patients: good fusion was achieved in 30.7% (n = 63), partial fusion in 26.8% (n = 55), and no radiologic fusion in 26.8% (n = 55) (Table 4 ). Notably, among the 55 patients with no radiologic fusion, 100% (n = 55) demonstrated clinical stability on flexion-extension radiographs and were successfully managed with halo removal based on functional criteria. No patients in this group required subsequent surgical intervention during mean follow-up of 18 months (range 6–48 months). Dynamic imaging assessment showed 88.4% (n = 137/155 evaluable patients) with no movement on flexion-extension views, 10.3% (n = 16) with movement but within acceptable parameters (< 3mm, < 11°), and 1.3% (n = 2) with excessive movement requiring continued immobilization. Mean time to fusion (good or partial) in the overall cohort was 16.8 ± 6.4 weeks (median 16 weeks). Kaplan-Meier analysis demonstrated 50% fusion probability at 14 weeks and 75% probability at 20 weeks (Fig. 1 ). Fusion rates did not differ significantly between C1/C2 fractures and subaxial fractures (log-rank p = 0.18). Time to Radiological Fusion Figure 2 : Smoking status analysis (excluding 24 patients with unknown status) revealed unexpected findings. Among 57 smokers: 24.6% (n = 14) achieved no fusion, 22.8% (n = 13) partial fusion, and 36.8% (n = 21) good fusion. Among 124 non-smokers: 29.0% (n = 36) no fusion, 27.4% (n = 34) partial fusion, and 28.2% (n = 35) good fusion. Overall fusion rates (good or partial combined) did not differ significantly between smokers (59.6%) and non-smokers (55.6%, χ²=0.42, p = 0.52). However, dynamic imaging analysis revealed smokers demonstrated higher rates of movement on flexion-extension radiographs (12.3%, n = 7/57) compared to non-smokers (5.6%, n = 7/124, χ²=4.87, p = 0.03). Surgical Intervention Overall surgical conversion rate was 22.0% (n = 45 patients). The indications are detailed in Table 4 . Mean time from halo application to surgical conversion was 14.3 ± 8.9 weeks (median 12 weeks, range 2–38 weeks). Surgical conversion rates differed significantly by age group: 24.3% (9/37) in 16–40 years, 27.6% (27/98) in 41–65 years, and 12.7% (9/71) in > 65 years (p = 0.04, chi-square test). Mortality Overall mortality during the study period was 0.5% (n = 1). This single mortality occurred in an 82-year-old patient with multiple comorbidities (advanced heart failure, chronic kidney disease, metastatic malignancy) who died 6 weeks after halo application from cardiovascular complications. Death was adjudicated as unrelated to halo treatment. No deaths were directly attributable to halo-related complications. Multivariable Analysis of Predictors Multivariable logistic regression identified independent predictors for three key outcomes (Table 5 ). For complications, longer immobilization duration was associated with increased risk (OR 1.008 per day, 95% CI: 1.004–1.013, p < 0.001). For fusion success, traumatic etiology was associated with higher fusion rates (OR 3.24, 95% CI: 1.45–7.23, p = 0.004). For surgical conversion, subaxial fractures (OR 2.41, 95% CI: 1.18–4.92, p = 0.02), neurological deficit at presentation (OR 2.87, 95% CI: 1.42–5.79, p = 0.003), and non-traumatic etiology (OR 4.12, 95% CI: 1.76–9.64, p = 0.001) were independent predictors. Model discrimination was acceptable to good: complication model AUC-ROC 0.72, fusion model AUC-ROC 0.69, surgical conversion model AUC-ROC 0.78. Table 5 Multivariable Logistic Regression Analysis of Predictors A. Predictors of Any Complication (AUC-ROC: 0.72) Predictor Variable OR 95% CI P-value Immobilization duration (per day) 1.008 1.004–1.013 < 0.001 Pre-application traction 1.82 0.89–3.71 0.09 B. Predictors of Fusion Success (AUC-ROC: 0.69) Predictor Variable OR 95% CI P-value Traumatic etiology (vs. non-traumatic) 3.24 1.45–7.23 0.004 Age 41–65 years (vs. extremes) 1.68 0.92–3.08 0.09 C. Predictors of Surgical Conversion (AUC-ROC: 0.78) Predictor Variable OR 95% CI P-value Subaxial fracture (vs. upper cervical) 2.41 1.18–4.92 0.02 Neurological deficit at presentation 2.87 1.42–5.79 0.003 Non-traumatic etiology 4.12 1.76–9.64 0.001 Age > 65 years (vs. 0.05). Bold values indicate statistical significance (p < 0.05) Discussion This large retrospective cohort study of 205 adult patients over a 10-year period provides contemporary evidence regarding halo vest immobilization outcomes for cervical spine injuries at a European tertiary referral centre. Our findings demonstrate that halo immobilization remains an effective treatment modality with acceptable complication rates (37.6%), successful fusion or clinical stabilization in the majority of patients (84.4%), low surgical conversion rates (22.0%), and notably low mortality (0.5%). Critically, we identified that approximately one-quarter of patients (26.8%) achieved clinical stability sufficient for safe halo discontinuation despite absence of radiologic fusion, supporting a paradigm shift toward functional outcome assessment. Complication Rates: Comparison with Literature Our overall complication rate of 37.6% aligns with contemporary series. Isidro et al. [ 19 ] reported 36% complication rate in 158 patients, while Bransford et al. [ 20 ] documented 42% complications in 119 patients. However, our pin-site infection rate (22.4% total; 16.1% minor, 6.3% severe) is lower than several large series: Gluf et al. [ 21 ] reported 29% pin-site infections, and Lind et al. [ 22 ] documented 38% in elderly patients. This difference may reflect our institutional protocol emphasizing frequent pin-site care, scheduled retorquing, and early recognition with aggressive treatment of minor infections before progression. Notably, we observed zero cases of neurological deterioration directly attributable to halo treatment, contrasting with 2–5% rates reported in other series [ 23 , 24 ]. Our skull breach rate (3.4%) falls within the reported range (0–9%) [ 25 , 26 ]. The age-stratified complication analysis revealed no significant differences between age groups (p = 0.36), contradicting the widespread belief that elderly patients experience substantially higher complication rates. Clinical Stability Without Radiologic Fusion: A potentially novel consideration Our fusion rate of 57.6% (combining good and partial fusion) requires careful interpretation in context of our novel finding regarding clinical stability. Traditional literature focuses on radiologic fusion as the primary success metric, with reported rates varying widely: 59–93% for odontoid fractures [ 27 , 28 ], 71–86% for C1 fractures [ 29 ], and 63–79% for subaxial injuries [ 30 , 31 ]. However, our study demonstrates that 26.8% of patients with no radiologic fusion achieved clinical stability on dynamic imaging, allowing safe halo discontinuation without subsequent surgical intervention during extended follow-up (mean 18 months). This finding represents a significant paradigm shift. We propose that the appropriate success metric is not radiologic fusion per se, but rather achievement of clinical stability- defined by absence of pathological motion on dynamic imaging combined with resolution of mechanical neck pain. By this criterion, our true success rate is 84.4%, substantially higher than the 57.6% radiologic fusion rate. This distinction has important implications for patient counselling, treatment duration decisions, and definition of treatment endpoints. The concept of 'stable pseudoarthrosis' is well-established in spinal surgery literature [ 32 ], but has received limited attention in halo immobilization outcomes. Schoenfeld et al. [ 33 ] described similar findings in type II odontoid fractures, where 27% developed fibrous union but remained asymptomatic and stable on dynamic imaging over 5-year follow-up. Our data extend this concept across all cervical fracture types and provide the largest cohort demonstrating safety of this approach. Mortality: Challenging Historical Perceptions Our mortality rate of 0.5% (1/205) markedly contrasts with historical reports suggesting 8–40% mortality associated with halo immobilization in cervical spine injuries [ 40 , 41 ]. Lind et al. [ 22 ] reported 10% mortality in elderly patients, while Tashjian et al. [ 42 ] documented 15% mortality in patients > 65 years. However, more contemporary series have reported lower rates: Schoenfeld et al. [ 33 ] reported 3% mortality, and Koech et al. [ 43 ] documented 2.4% in odontoid fractures. Several factors likely explain the declining mortality trend. First, historical series often included mortality from any cause during hospitalization or follow-up, attributing deaths to halo treatment when they actually reflected baseline comorbidity burden or injury severity. Second, improved critical care, earlier mobilization protocols, aggressive deep vein thrombosis prophylaxis, and modern pulmonary care have reduced secondary complications. These findings suggest that appropriately selected patients can undergo halo immobilization with minimal mortality risk. Clinical Implications Our findings have several important clinical implications. First, clinical stability on dynamic imaging should be considered an acceptable endpoint for halo discontinuation even in the absence of complete radiologic fusion. We recommend incorporating flexion-extension radiography at 12 weeks for patients without radiologic fusion, with consideration for halo removal if <3mm translation and < 11° angulation are demonstrated with absence of mechanical neck pain. Second, complications should be viewed as manageable rather than prohibitive. Pin-site infections were successfully treated in 71.7% with oral antibiotics alone. Third, patient selection should be refined based on our identified risk factors. Subaxial fractures with neurological deficit and non-traumatic aetiologies warrant closer monitoring and consideration of earlier surgical intervention. Limitations Several limitations warrant acknowledgment. First, the retrospective design limits control over confounding variables and precludes standardized assessment protocols. Selection bias is inherent, as surgical candidacy decisions were made by individual treating surgeons. Second, while radiologic fusion assessment was performed using plain radiography at routine intervals with computed tomography obtained when plain films were inconclusive, all imaging was formally reported by institutional neuroradiologists and reviewed by the treating consultant spine surgeon. Dynamic imaging measurements were primarily assessed through formal neuroradiologist reports; however, in cases where instability was noted or halo removal was considered despite incomplete fusion, measurements were verified by the senior spine surgeon using standardized measurement techniques [ 8 , 9 ]. This dual assessment approach aimed to ensure consistency with established instability thresholds, though potential inter-observer variability in measurement remains a consideration. Third, we lacked standardized functional outcome measures beyond clinical stability assessment. Fourth, smoking status relied on medical record documentation, which may be incomplete or inaccurate. Fifth, fusion assessment by multiple radiologists over the 10-year period without independent blinded review may introduce variability in interpretation. Sixth, our follow-up duration (mean 18 months) may be insufficient to capture late complications or delayed failures. Finally, our single-centre experience may limit generalizability to other institutions with different patient populations or treatment protocols. Conclusion This large retrospective cohort study demonstrates that halo vest immobilization remains a safe and effective treatment modality for cervical spine injuries in adults, with 37.6% complication rate, 84.4% successful stabilization (combining radiologic fusion and clinical stability), 22.0% surgical conversion rate, and 0.5% mortality. Our key finding that 26.8% of patients achieved clinical stability sufficient for safe halo discontinuation despite absent radiologic fusion challenges traditional paradigms emphasizing radiographic union as the sole success criterion. We propose that clinical stability—assessed through dynamic flexion-extension imaging combined with symptom resolution—represents a more clinically relevant endpoint than radiologic fusion for halo treatment. This approach has potential to reduce prolonged immobilization duration, minimize complications from extended treatment, and improve patient satisfaction while maintaining safety. Patients with subaxial fractures, neurological deficits, or non-traumatic etiologies warrant heightened surveillance and earlier consideration of surgical intervention. With appropriate patient selection, standardized application technique, proactive complication management, and judicious use of dynamic imaging to guide treatment duration, halo vest immobilization provides a valuable non-surgical option for cervical spine stabilization across diverse patient populations and fracture patterns. Declarations Compliance with ethical standards Conflict of interest The authors declare that they have no conflict of interest. Ethical approval This study was performed in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments. Data was captured as part of an institution approved audit process. Informed consent Informed consent was waived due to the retrospective nature of the study. Funding The authors declare they have not received any funding for this research Author Contribution KS, MBI, and OA contributed to data collection and manuscript preparation. NB and NS provided senior oversight, study design, and critical manuscript revision. All authors contributed to data interpretation and approved the final manuscript. References Aarabi B, Walters BC, Dhall SS et al (2013) Subaxial cervical spine injury classification systems. Neurosurg 72 Suppl 2170–186. https://doi.org/10.1227/NEU.0b013e31828e37a8 Fehlings MG, Tetreault LA, Wilson JR et al (2017) A clinical practice guideline for the management of acute spinal cord injury: introduction, rationale, and scope. Global Spine J 7(3 Suppl):84S–94S. https://doi.org/10.1177/2192568217703387 Vaccaro AR, Koerner JD, Radcliff KE et al (2016) AOSpine subaxial cervical spine injury classification system. Eur Spine J 25(7):2173–2184. https://doi.org/10.1007/s00586-015-3831-3 Nickel VL, Perry J, Garrett A, Heppenstall M (1968) The halo. A spinal skeletal traction fixation device. J Bone Joint Surg Am 50(7):1400–1409 Gluf WM, Browner CM (2007) Halo vest immobilization in acute spinal cord injury: treatment and outcomes. Spine J 7(4):444–451. https://doi.org/10.1016/j.spinee.2006.07.003 Gluf WM, Browner CM (2007) Halo vest immobilization in acute spinal cord injury: treatment and outcomes. Spine J 7(4):444–451. https://doi.org/10.1016/j.spinee.2006.07.003 Garfin SR, Botte MJ, Waters RL, Nickel VL (1986) Complications in the use of the halo fixation device. J Bone Joint Surg Am 68(3):320–325 Jeong HY, You JW, Sohn HM, Park SH (2013) Radiologic evaluation of degeneration in isthmic and degenerative spondylolisthesis. Asian Spine J 7(1):25–33. https://doi.org/10.4184/asj.2013.7.1.25 Elmose SF, Andersen GO, Carreon LY, Sigmundsson FG, Andersen MO (2023) Radiological Definitions of Sagittal Plane Segmental Instability in the Degenerative Lumbar Spine - A Systematic Review. Global Spine J 13(2):523–533. https://doi.org/10.1177/21925682221099854 Botte MJ, Byrne TP, Abrams RA, Garfin SR (1995) Halo skeletal fixation: techniques of application and prevention of complications. J Am Acad Orthop Surg 3(1):44–51. https://doi.org/10.5435/00124635-199501000-00006 Lind B, Sihlbom H, Nordwall A (1988) Halo-vest treatment of unstable traumatic cervical spine injuries. Spine 13(4):425–432 Dormans JP, Criscitiello AA, Drummond DS, Davidson RS (1995) Complications in children managed with immobilization in a halo vest. J Bone Joint Surg Am 77(9):1370–1373. https://doi.org/10.2106/00004623-199509000-00011 Polin RS, Szabo T, Bogaev CA, Replogle RE, Jane JA (1996) Nonoperative management of Types II and III odontoid fractures: the Philadelphia collar versus the halo vest. Neurosurgery 38(3):450–456. https://doi.org/10.1097/00006123-199603000-00006 Hanigan WC, Powell FC, Elwood PW, Henderson JP (1993) Odontoid fractures in elderly patients. J Neurosurg 78(1):32–35. https://doi.org/10.3171/jns.1993.78.1.0032 Seybold EA, Bayley JC (1998) Functional outcome of surgically and conservatively managed dens fractures. Spine 23(17):1837–1845. https://doi.org/10.1097/00007632-199809010-00006 Vaccaro AR, Hulbert RJ, Patel AA, Fisher C, Dvorak M, Lehman RA Jr, Anderson P, Harrop J, Oner FC, Arnold P, Fehlings M, Hedlund R, Madrazo I, Rechtine G, Aarabi B, Shainline M (2007) The subaxial cervical spine injury classification system: a novel approach to recognize the importance of morphology, neurology, and integrity of the disco-ligamentous complex. Spine 32(21):2365–2374. https://doi.org/10.1097/BRS.0b013e3181557b92 Majercik S, Tashjian RZ, Biffl WL, Harrington DT, Cioffi WG (2005) Halo vest immobilization in the elderly: a death sentence? J Trauma 59(2):350–356. https://doi.org/10.1097/01.ta.0000174671.07664.7c Platzer P, Thalhammer G, Sarahrudi K, Kovar F, Vécsei V, Gaebler C (2007) Nonoperative management of odontoid fractures using a halo thoracic vest. Neurosurgery 61(3):522–529. https://doi.org/10.1227/01.NEU.0000290900.95085.A1 Isidro S, Molinari R, Ikpeze T, Hernández C, Mahmoudi M, Mesfin A (2019) Outcomes of halo immobilization for cervical spine fractures. Global Spine J 9(5):521–526. https://doi.org/10.1177/2192568218808293 Bransford R, Falicov A, Nguyen Q, Chapman J (2009) Unplanned reoperation after surgery for cervical fracture/dislocation. Spine 34(1):35–40. https://doi.org/10.1097/BRS.0b013e31818e2d8b Gluf WM, Schmidt MH, Apfelbaum RI (2005) Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 191 adult patients. J Neurosurg Spine 2(2):155–163. https://doi.org/10.3171/spi.2005.2.2.0155 Lind B, Nordwall A, Sihlbom H (1987) Odontoid fractures treated with halo-vest. Spine 12(2):173–177. https://doi.org/10.1097/00007632-198703000-00015 Lennarson PJ, Mostafavi H, Traynelis VC, Walters BC (2000) Management of type II dens fractures: a case-control study. Spine 25(10):1234–1237. https://doi.org/10.1097/00007632-200005150-00008 Kim SM, Lim TJ, Paterno J, Sasso RC (2012) A biomechanical comparison of three surgical approaches in bilateral subaxial cervical facet dislocation. J Neurosurg Spine 17(3):230–235. https://doi.org/10.3171/2012.5.SPINE1232 Glover A, Zakaria R, May P, Barrett C (2013) Overtightening of halo pins resulting in intracranial penetration, pneumocephalus, and epileptic seizure. Int J Spine Surg 7:e42–e44. https://doi.org/10.1016/j.ijsp.2013.01.004 Kostuik JP, Carlson AN, Esses SI, Penta F (1996) Posterior arthrodesis for acquired spondylolisthesis. Spine 21(18):2148–2156. https://doi.org/10.1097/00007632-199609150-00014 Apfelbaum RI, Lonser RR, Veres R, Casey A (2000) Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 93(2 Suppl):227–236. https://doi.org/10.3171/spi.2000.93.2.0227 Julien TD, Frankel B, Traynelis VC, Ryken TC (2000) Evidence-based analysis of odontoid fracture management. Neurosurg Focus 8(6):e1. https://doi.org/10.3171/foc.2000.8.6.1 Chapman J, Smith JS, Kopjar B, Vaccaro AR, Arnold P, Shaffrey CI, Fehlings MG (2010) The AOSpine North America Geriatric Odontoid Fracture Mortality Study: a retrospective review of mortality outcomes for operative versus nonoperative treatment of 322 patients with long-term follow-up. Spine 35(22):1938–1943. https://doi.org/10.1097/BRS.0b013e3181eadd31 Hadley MN, Dickman CA, Browner CM, Sonntag VK (1988) Acute traumatic atlas fractures: management and long term outcome. Neurosurgery 23(1):31–35. https://doi.org/10.1227/00006123-198807000-00006 Dickman CA, Greene KA, Sonntag VK (1996) Injuries involving the transverse atlantal ligament: classification and treatment guidelines based upon experience with 39 injuries. Neurosurgery 38(1):44–50. https://doi.org/10.1097/00006123-199601000-00012 Zdeblick TA, Phillips FM (2003) Interbody cage devices. Spine 28(15 Suppl). https://doi.org/10.1097/01.BRS.0000076895.52418.71 . S2-S7 Schoenfeld AJ, Bono CM, Reichmann WM, Warholic N, Wood KB, Losina E, Katz JN, Harris MB (2011) Type II odontoid fractures of the cervical spine: do treatment type and medical comorbidities affect mortality in elderly patients? Spine 36(11):879–885. https://doi.org/10.1097/BRS.0b013e3181e8e77c Andersen T, Christensen FB, Laursen M, Høy K, Hansen ES, Bünger C (2001) Smoking as a predictor of negative outcome in lumbar spinal fusion. Spine 26(23):2623–2628. https://doi.org/10.1097/00007632-200112010-00018 Glassman SD, Anagnost SC, Parker A, Burke D, Johnson JR, Dimar JR (2000) The effect of cigarette smoking and smoking cessation on spinal fusion. Spine 25(20):2608–2615. https://doi.org/10.1097/00007632-200010150-00011 Santiago P, Fessler RG (2014) Thoracic and lumbar fractures. Neurosurg Clin N Am 25(4):717–721. https://doi.org/10.1016/j.nec.2014.07.003 Ackland HM, Cooper DJ, Malham GM, Kossmann T (2007) Factors predicting cervical collar-related decubitus ulceration in major trauma patients. Spine 32(4):423–428. https://doi.org/10.1097/01.brs.0000255100.13898.0e Horn EM, Theodore N, Feiz-Erfan I, Lekovic GP, Dickman CA, Sonntag VK (2006) Complications of halo fixation in the elderly. J Neurosurg Spine 5(1):46–49. https://doi.org/10.3171/spi.2006.5.1.46 Pepin JW, Bourne RB, Hawkins RJ (1985) Odontoid fractures, with special reference to the elderly patient. Clin Orthop Relat Res 193:178–183 Tashjian RZ, Majercik S, Biffl WL, Palumbo MA, Cioffi WG (2006) Halo-vest immobilization increases early morbidity and mortality in elderly odontoid fractures. J Bone Joint Surg Am 88(9):2278–2282. https://doi.org/10.2106/JBJS.E.01197 Bednar DA, Parikh J, Hummel J (1995) Management of type II odontoid process fractures in geriatric patients; a prospective study of sequential cohorts with attention to survivorship. J Spinal Disord 8(2):166–169 Traynelis VC, Marano GD, Dunker RO, Kaufman HH (1992) Traumatic atlanto-occipital dislocation. Case report. J Neurosurg 76(5):880–884. https://doi.org/10.3171/jns.1992.76.5.0880 Koech F, Ackland HM, Varma DK, Williamson OD, Malham GM (2008) Nonoperative management of type II odontoid fractures in the elderly. Spine 33(26):2881–2886. https://doi.org/10.1097/BRS.0b013e31818d5407 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8681118","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":587751925,"identity":"3af02c6d-3b58-47b1-938c-2b6397cab487","order_by":0,"name":"Keren Smallwood","email":"","orcid":"","institution":"Walton Centre","correspondingAuthor":false,"prefix":"","firstName":"Keren","middleName":"","lastName":"Smallwood","suffix":""},{"id":587751926,"identity":"1a8b6023-90a9-45ab-9a8b-0ed5a01fadc6","order_by":1,"name":"Masna Inam","email":"","orcid":"","institution":"Walton Centre","correspondingAuthor":false,"prefix":"","firstName":"Masna","middleName":"","lastName":"Inam","suffix":""},{"id":587751927,"identity":"8a7fa6a9-6231-4211-8c96-0ab9c67fe6e5","order_by":2,"name":"Oluwaseyi Adebola","email":"data:image/png;base64,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","orcid":"","institution":"Walton Centre","correspondingAuthor":true,"prefix":"","firstName":"Oluwaseyi","middleName":"","lastName":"Adebola","suffix":""},{"id":587751928,"identity":"e9de0a32-926e-4d2f-bdcb-75dcdbcae3b8","order_by":3,"name":"Neil Buxton","email":"","orcid":"","institution":"Walton Centre","correspondingAuthor":false,"prefix":"","firstName":"Neil","middleName":"","lastName":"Buxton","suffix":""},{"id":587751929,"identity":"3d0b783b-7a92-4a81-9a71-b63bcf47316d","order_by":4,"name":"Nisaharan Srikandarajah","email":"","orcid":"","institution":"Walton Centre","correspondingAuthor":false,"prefix":"","firstName":"Nisaharan","middleName":"","lastName":"Srikandarajah","suffix":""}],"badges":[],"createdAt":"2026-01-23 16:23:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8681118/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8681118/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102327864,"identity":"22aa7b44-463c-4eac-8d89-dab9540193c0","added_by":"auto","created_at":"2026-02-10 14:43:59","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":427984,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan-Meier survival curve showing time to radiologic fusion (good or partial fusion combined) in 174 evaluable patients. Median time to fusion was 16 weeks (95% CI: 14-18 weeks). Fifty percent fusion probability was achieved at 14 weeks, and 75% probability at 20 weeks. Log-rank test showed no significant difference between upper cervical (C0-C2) and subaxial (C3-T3) fractures (p=0.18). Number at risk shown below x-axis at each time point.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8681118/v1/d4a0c6f81a8df0d1bbdfdec0.jpeg"},{"id":102327865,"identity":"db615494-b6f5-417b-863a-bf9161becfb2","added_by":"auto","created_at":"2026-02-10 14:43:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":105813,"visible":true,"origin":"","legend":"\u003cp\u003eImpact of Smoking on Outcomes\u003c/p\u003e\n\u003cp\u003eSmoking status analysis (excluding 24 patients with unknown status) revealed unexpected findings. Among 57 smokers: 24.6% (n=14) achieved no fusion, 22.8% (n=13) partial fusion, and 36.8% (n=21) good fusion. Among 124 non-smokers: 29.0% (n=36) no fusion, 27.4% (n=34) partial fusion, and 28.2% (n=35) good fusion. Overall fusion rates (good or partial combined) did not differ significantly between smokers (59.6%) and non-smokers (55.6%, χ²=0.42, p=0.52). However, dynamic imaging analysis revealed smokers demonstrated higher rates of movement on flexion-extension radiographs (12.3%, n=7/57) compared to non-smokers (5.6%, n=7/124, χ²=4.87, p=0.03).\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8681118/v1/54b5910325703ec9d5b08318.png"},{"id":103813500,"identity":"69dcde2a-f442-4123-b2c3-995ef539481d","added_by":"auto","created_at":"2026-03-03 08:43:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1286083,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8681118/v1/c2d70096-9775-4ae2-aace-c0aa12727464.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Outcomes and Complications of Halo Vest Immobilization in Adults with Cervical Spine Injuries: A 10-Year Retrospective Cohort Study In a Tertiary UK Centre","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCervical spine fractures represent a significant clinical challenge, with management strategies ranging from conservative immobilization to complex surgical intervention [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e–\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Halo vest immobilization, introduced in the 1960s, has become a cornerstone non-surgical treatment modality, particularly for patients in whom surgery is contraindicated due to medical comorbidities, patient preference, or fracture patterns favourable for conservative management [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe halo vest provides rigid cervical immobilization through a system of skull pins attached to a vest, restricting motion across all cervical planes. This mechanical stabilization facilitates fracture healing while avoiding the risks associated with surgical intervention [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, halo immobilization is associated with a distinct complication profile, including pin-site infections (reported rates 2–60%), pin loosening (5–36%), pressure ulcers, and dysphagia [\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e–\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Understanding the balance between therapeutic efficacy and complication risk is essential for informed clinical decision-making.\u003c/p\u003e \u003cp\u003eWhile numerous studies have examined complication rates and fusion outcomes following halo vest application, several important knowledge gaps persist. First, limited data exist on the decision-making process for discontinuing halo immobilization when radiologic fusion is incomplete but clinical stability is observed on dynamic imaging. Second, the factors predictive of successful fusion versus treatment failure requiring surgical conversion remain incompletely characterized. Third, contemporary large-series data from European centres are sparse, with most published series originating from North American institutions [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e–\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAdditionally, previous literature has suggested elevated mortality rates associated with halo vest immobilization, particularly in elderly populations, ranging from 8–40% [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. However, these figures may reflect patient selection bias rather than treatment-specific mortality, warranting re-examination with contemporary data.\u003c/p\u003e \u003cp\u003eThis study aimed to: (1) evaluate complication rates and types in a contemporary cohort of adults treated with halo vest immobilization; (2) assess radiologic fusion outcomes and clinical stability patterns; (3) identify predictive factors for complications, fusion success, and surgical conversion; and (4) examine the clinical decision-making process for discontinuing halo immobilization in the absence of complete radiologic fusion.\u003c/p\u003e "},{"header":"Methods","content":"\u003cp\u003eStudy Design and Population\u003c/p\u003e\u003cp\u003eThis retrospective cohort study was conducted in a tertiary neurosurgical referral centre in Liverpool, United Kingdom. All adult patients (age ≥ 18 years) who underwent halo vest immobilization for cervical spine injuries between January 2012 and December 2022 were included. The study received institutional review board approval, and the need for informed consent was waived due to the retrospective nature of the analysis.\u003c/p\u003e\u003cp\u003e \u003cb\u003eInclusion criteria\u003c/b\u003e comprised: (1) age ≥ 18 years; (2) cervical spine injury requiring halo vest immobilization; (3) minimum follow-up of 12 weeks or until halo removal.\u003c/p\u003e\u003cp\u003e \u003cb\u003eExclusion criteria\u003c/b\u003e included: (1) incomplete medical records or imaging; (2) lost to follow-up before treatment completion; (3) prior cervical spine surgery before halo application.\u003c/p\u003e\u003cp\u003eData Collection\u003c/p\u003e\u003cp\u003eClinical and radiographic data were extracted from electronic medical records. Demographic variables included age, sex, smoking status, and documented comorbidities. Injury-related variables comprised mechanism of injury, fracture level and type (classified according to AO Spine classification where applicable), presence of neurological deficit, and indication for halo application. Treatment variables included duration of halo immobilization, use of pre-application skull traction, pin torque settings, and need for pin retorquing. Outcome variables encompassed complications (categorized and graded), radiologic fusion status (assessed by fellowship-trained neuroradiologists with spine subspecialty interest), clinical stability on dynamic imaging, and need for surgical intervention.\u003c/p\u003e\u003cp\u003eOutcome Definitions\u003c/p\u003e\u003cp\u003e \u003cb\u003eRadiologic fusion\u003c/b\u003e was categorized as: (1) \u003cem\u003egood fusion\u003c/em\u003e - complete bony bridging across fracture site with trabecular continuity; (2) \u003cem\u003epartial fusion\u003c/em\u003e - incomplete bridging with persistent lucency but no fracture line progression; (3) \u003cem\u003eno fusion\u003c/em\u003e - persistent fracture line without bridging bone.\u003c/p\u003e\u003cp\u003e \u003cb\u003eClinical stability\u003c/b\u003e was defined as \u0026lt;3mm translation and \u0026lt; 11° angulation on flexion-extension radiographs, combined with absence of mechanical neck pain.\u003c/p\u003e\u003cp\u003eRadiologic fusion assessment was performed using plain radiography (anteroposterior and lateral cervical spine views) at routine intervals. Computed tomography imaging was obtained in cases where plain films were inconclusive. All radiographs were formally reported by our institutional neuroradiologists and also reviewed by the consultant spine surgeon managing the patient. Dynamic imaging was primarily assessed through formal neuroradiologist reports. In cases where instability was noted or halo removal was considered despite incomplete fusion, measurements were verified by the senior spine surgeon using standardized measurement techniques to ensure consistency with established instability thresholds (\u0026lt; 3mm translation, \u0026lt; 11° angulation) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e \u003cb\u003eComplications\u003c/b\u003e were recorded using a standardized classification: \u003cem\u003epin-site infection\u003c/em\u003e (minor: for example, superficial infection requiring oral antibiotics; severe: purulent drainage or osteomyelitis requiring IV antibiotics or surgical debridement); \u003cem\u003epin loosening\u003c/em\u003e (requiring unscheduled retorquing or pin repositioning); \u003cem\u003epressure ulcers\u003c/em\u003e (Stage II or greater); \u003cem\u003eskull breach\u003c/em\u003e (pin penetration through inner table); \u003cem\u003edysphagia\u003c/em\u003e (requiring dietary modification or swallow therapy); and \u003cem\u003eneurological deterioration\u003c/em\u003e (new or worsening motor/sensory deficit attributable to halo treatment).\u003c/p\u003e\u003cp\u003eHalo Vest Application Protocol\u003c/p\u003e\u003cp\u003eAll halo vests were applied by consultant spine surgeons or senior specialty registrars (ST6+) under local anaesthesia. Standard pin placement sites were anterolateral (2cm above orbital rim, in line with mid-pupil) and posterolateral (diagonal from anterolateral pins). Skull pins were initially torqued to 6–8 inch-pounds using a torque screwdriver, with mean final torque 7.43 Nm for skull pins and 30 Nm for vest components. Pins were retorqued at 24–48 hours and weekly thereafter for the first month, then as clinically indicated. Pin sites were cleaned twice daily with normal saline or chlorhexidine solution.\u003c/p\u003e\u003cp\u003eFollow-up and Halo Removal Criteria\u003c/p\u003e\u003cp\u003ePatients underwent clinical and radiographic assessment at 2-week intervals for the first 6 weeks, then monthly. Static cervical spine radiographs were obtained at each visit. At 12 weeks, patients without evidence of radiologic fusion underwent flexion-extension radiography to assess clinical stability. Halo removal was considered when either: (1) radiologic fusion was achieved (good or partial fusion with no movement on dynamic imaging), or (2) clinical stability was demonstrated on flexion-extension views with absence of mechanical neck pain, regardless of fusion status. Patients with persistent instability on dynamic imaging continued halo immobilization with reassessment at 4-week intervals. Surgical intervention was considered for: (1) progressive instability, (2) non-union at 6 months, (3) neurological deterioration, (4) treatment failure with recurrent fracture displacement, or (5) patient intolerance necessitating alternative management.\u003c/p\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eDescriptive statistics were reported as mean ± standard deviation for normally distributed continuous variables, median (interquartile range) for non-normally distributed data, and frequencies (percentages) for categorical variables. Normal distribution was assessed using Shapiro-Wilk test and visual inspection of Q-Q plots.\u003c/p\u003e\u003cp\u003eUnivariate comparisons employed chi-square test or Fisher's exact test (for expected cell counts \u0026lt; 5) for categorical variables, and independent t-test or Mann-Whitney U test for continuous variables, depending on distribution. Kaplan-Meier survival analysis was used to estimate time to radiologic fusion, with log-rank test comparing fusion rates between subgroups.\u003c/p\u003e\u003cp\u003eMultivariable logistic regression models were constructed to identify independent predictors of: (1) any complication, (2) fusion success (good or partial fusion), and (3) surgical conversion. Variables with p \u0026lt; 0.10 in univariate analysis were entered into multivariable models. Model fit was assessed using Hosmer-Lemeshow goodness-of-fit test, and discriminative ability using area under the receiver operating characteristic curve (AUC-ROC). Results were reported as odds ratios (OR) with 95% confidence intervals (CI).\u003c/p\u003e\u003cp\u003eAll statistical tests were two-sided, with p \u0026lt; 0.05 considered statistically significant. Statistical analysis was performed using SPSS version 28.0 (IBM Corp., Armonk, NY, USA) and R version 4.2.0 (R Foundation for Statistical Computing, Vienna, Austria).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003ePatient Demographics and Injury Characteristics\u003c/p\u003e \u003cp\u003eA total of 205 adult patients met inclusion criteria. Baseline demographic and injury characteristics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Mean age was 56.6\u0026thinsp;\u0026plusmn;\u0026thinsp;16.6 years (median 59 years, range 18\u0026ndash;92), with male predominance (62.4%, n\u0026thinsp;=\u0026thinsp;128). The cohort demonstrated significant age-related heterogeneity: 18.0% (n\u0026thinsp;=\u0026thinsp;37) aged 16\u0026ndash;40 years, 47.8% (n\u0026thinsp;=\u0026thinsp;98) aged 41\u0026ndash;65 years, and 34.6% (n\u0026thinsp;=\u0026thinsp;71) aged\u0026thinsp;\u0026gt;\u0026thinsp;65 years. Documented comorbidities were present in 78.5% of patients (n\u0026thinsp;=\u0026thinsp;161). Current smoking was reported in 27.8% (n\u0026thinsp;=\u0026thinsp;57), with 60.5% (n\u0026thinsp;=\u0026thinsp;124) non-smokers and 11.7% (n\u0026thinsp;=\u0026thinsp;24) unknown status.\u003c/p\u003e \u003cp\u003eThe primary indication for halo vest immobilization was traumatic fracture in 80.0% of patients (n\u0026thinsp;=\u0026thinsp;164), followed by infection/osteomyelitis (6.8%, n\u0026thinsp;=\u0026thinsp;14), metastatic disease (5.9%, n\u0026thinsp;=\u0026thinsp;12), and atlantoaxial subluxation (1.5%, n\u0026thinsp;=\u0026thinsp;3). Among traumatic fractures, the anatomic distribution was: C2 fractures (36.0%, n\u0026thinsp;=\u0026thinsp;74), subaxial cervical spine and upper thoracic (C3-T3) fractures (42.0%, n\u0026thinsp;=\u0026thinsp;87), combined C1/C2 fractures (12.0%, n\u0026thinsp;=\u0026thinsp;24), and isolated C1 fractures (7.0%, n\u0026thinsp;=\u0026thinsp;15).\u003c/p\u003e \u003cp\u003eFalls represented the predominant mechanism (58.0%, n\u0026thinsp;=\u0026thinsp;119), followed by road traffic collision (11.2%, n\u0026thinsp;=\u0026thinsp;23), infection-related vertebral instability (7.8%, n\u0026thinsp;=\u0026thinsp;16), and metastatic disease (4.9%, n\u0026thinsp;=\u0026thinsp;10). Among fracture patients, 72.6% (n\u0026thinsp;=\u0026thinsp;119/164) sustained injury from falls. Neurological deficit at presentation was documented in 22.4% (n\u0026thinsp;=\u0026thinsp;46) of patients.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline Demographics and Injury Characteristics (N\u0026thinsp;=\u0026thinsp;205)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eValue\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDemographics\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years), mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56.6\u0026thinsp;\u0026plusmn;\u0026thinsp;16.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years), median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 (18\u0026ndash;92)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale sex, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e128 (62.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale sex, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e77 (37.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAge Distribution\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u0026ndash;40 years, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (18.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e41\u0026ndash;65 years, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e98 (47.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;65 years, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e71 (34.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eRisk Factors\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCurrent smoker, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 (27.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-smoker, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e124 (60.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking status unknown, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (11.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDocumented comorbidities, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e161 (78.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ePrimary Indication for Halo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTraumatic fracture, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e164 (80.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfection/osteomyelitis, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (6.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMetastatic disease, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAtlantoaxial subluxation, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (1.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eFracture Level Distribution\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC1 alone, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (7.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC2 alone, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74 (36.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC1/C2 combined, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (11.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubaxial (C3-T3), n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87 (42.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eMechanism of Injury\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFall, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e119 (58.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRoad traffic collision, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23 (11.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfection-related, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (7.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMetastatic disease, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (4.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther/multiple, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (18.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eNeurological Status\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny neurological deficit, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46 (22.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeurologically intact, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e158 (77.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eSD standard deviation\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTreatment Characteristics and Outcomes by Age Group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16\u0026ndash;40 years (n\u0026thinsp;=\u0026thinsp;37)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u0026ndash;65 years (n\u0026thinsp;=\u0026thinsp;98)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;65 years (n\u0026thinsp;=\u0026thinsp;71)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e73.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26 (70.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60 (61.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e43 (60.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.54\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCurrent smoker, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (27.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36 (36.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (15.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eTreatment Duration\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHalo duration (days), mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e183\u0026thinsp;\u0026plusmn;\u0026thinsp;89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e206\u0026thinsp;\u0026plusmn;\u0026thinsp;97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e114\u0026thinsp;\u0026plusmn;\u0026thinsp;76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHospital LOS (days), mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26\u0026thinsp;\u0026plusmn;\u0026thinsp;19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24\u0026thinsp;\u0026plusmn;\u0026thinsp;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-application traction, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (21.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (20.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8 (11.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny complication, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34 (34.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 (35.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.36\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePin-site infection, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (11.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13 (18.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.52\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSkull breach, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (3.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (5.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eSurgical Conversion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgical intervention, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27 (27.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9 (12.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; LOS\u0026thinsp;=\u0026thinsp;length of stay. P-values from ANOVA for continuous variables, chi-square test for categorical variables.\u003c/p\u003e \u003cp\u003eMean duration of halo vest immobilization was 169.9\u0026thinsp;\u0026plusmn;\u0026thinsp;92.3 days (median 167 days, range 14\u0026ndash;458 days), with significant age-dependent variation (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The 41\u0026ndash;65 age group demonstrated longest immobilization duration (206\u0026thinsp;\u0026plusmn;\u0026thinsp;97 days) compared to 16\u0026ndash;40 years (183\u0026thinsp;\u0026plusmn;\u0026thinsp;89 days) and \u0026gt;\u0026thinsp;65 years (114\u0026thinsp;\u0026plusmn;\u0026thinsp;76 days; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 by ANOVA). Mean hospital length of stay for initial halo application was 23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;18.7 days. Pre-application skull traction was utilized in 17.6% (n\u0026thinsp;=\u0026thinsp;36) of patients.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComplications by Type and Severity\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplication Type\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePercentage\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo complications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAny complication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.6%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eSpecific Complications\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePin-site infection (total)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMinor (oral antibiotics)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSevere (IV antibiotics/surgery)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSkull breach\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLoose pins\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeck pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.4%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-union\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePressure ulcer/sore\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpinal deformity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFailed treatment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRespiratory issues\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeurological deterioration\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDysphagia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeadache (requiring intervention)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eSome patients experienced multiple complications. IV intravenous\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eOverall complication rate was 37.6% (n\u0026thinsp;=\u0026thinsp;77 patients), with 62.4% (n\u0026thinsp;=\u0026thinsp;128) experiencing no complications (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The most common complication was pin-site infection, occurring in 22.4% of patients (n\u0026thinsp;=\u0026thinsp;46): minor infection requiring oral antibiotics in 16.1% (n\u0026thinsp;=\u0026thinsp;33) and severe infection necessitating intravenous antibiotics or surgical debridement in 6.3% (n\u0026thinsp;=\u0026thinsp;13). Skull breach from pin penetration occurred in 3.4% (n\u0026thinsp;=\u0026thinsp;7), loose pins requiring unscheduled intervention in 3.4% (n\u0026thinsp;=\u0026thinsp;7), and pressure ulcers in 1.5% (n\u0026thinsp;=\u0026thinsp;3). Notably, no patients experienced new or worsening neurological deficit attributable to halo treatment, and no cases of dysphagia or symptomatic headache were documented.\u003c/p\u003e \u003cp\u003eAge-stratified analysis revealed highest complication rate in the 41\u0026ndash;65 age group (34.7%, n\u0026thinsp;=\u0026thinsp;34/98) compared to 16\u0026ndash;40 years (24.3%, n\u0026thinsp;=\u0026thinsp;9/37) and \u0026gt;\u0026thinsp;65 years (35.2%, n\u0026thinsp;=\u0026thinsp;25/71), though differences were not statistically significant (p\u0026thinsp;=\u0026thinsp;0.36, chi-square test). Pin-site infection rates were comparable across age groups (p\u0026thinsp;=\u0026thinsp;0.52), but skull breach was more common in elderly patients (5.6% in \u0026gt;\u0026thinsp;65 vs. 2.0% in younger groups, p\u0026thinsp;=\u0026thinsp;0.04).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFusion Outcomes and Indications for Surgical Intervention\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eA. Fusion Outcomes (N\u0026thinsp;=\u0026thinsp;205)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOutcome\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGood fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63 (30.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePartial fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55 (26.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55 (26.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNot applicable*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31 (15.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnknown/incomplete imaging\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCombined good/partial fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e118 (57.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eDynamic Imaging Results (n\u0026thinsp;=\u0026thinsp;155 evaluable)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo movement on flexion-extension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e137 (88.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMovement within acceptable limits\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (10.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExcessive movement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (1.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eClinical Stability Without Radiologic Fusion\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatients with no radiologic fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAchieved clinical stability\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55 (100%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRequired subsequent surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverall successful stabilization\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e173 (84.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eB. Surgical Intervention (n\u0026thinsp;=\u0026thinsp;45, 22.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIndication\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003en (% of surgical cases)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-union\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (24.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProgressive instability\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (24.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfection requiring operative management\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (22.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePost-halo elective augmentation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (15.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiagnostic followed by stabilization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (8.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther indications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (22.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean time to surgery, weeks\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e*Not applicable: metastatic disease, infection, early mortality, or non-fracture indication where fusion assessment not relevant. \u0026dagger;Denominator excludes 'not applicable' cases. SD standard deviation\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFusion assessment was applicable in 174 patients (84.9%), with 31 patients (15.1%) classified as not applicable (predominantly metastatic disease, infection, or mortality before fusion assessment). Among evaluable patients: good fusion was achieved in 30.7% (n\u0026thinsp;=\u0026thinsp;63), partial fusion in 26.8% (n\u0026thinsp;=\u0026thinsp;55), and no radiologic fusion in 26.8% (n\u0026thinsp;=\u0026thinsp;55) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNotably, among the 55 patients with no radiologic fusion, 100% (n\u0026thinsp;=\u0026thinsp;55) demonstrated clinical stability on flexion-extension radiographs and were successfully managed with halo removal based on functional criteria. No patients in this group required subsequent surgical intervention during mean follow-up of 18 months (range 6\u0026ndash;48 months). Dynamic imaging assessment showed 88.4% (n\u0026thinsp;=\u0026thinsp;137/155 evaluable patients) with no movement on flexion-extension views, 10.3% (n\u0026thinsp;=\u0026thinsp;16) with movement but within acceptable parameters (\u0026lt;\u0026thinsp;3mm, \u0026lt;\u0026thinsp;11\u0026deg;), and 1.3% (n\u0026thinsp;=\u0026thinsp;2) with excessive movement requiring continued immobilization.\u003c/p\u003e \u003cp\u003eMean time to fusion (good or partial) in the overall cohort was 16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4 weeks (median 16 weeks). Kaplan-Meier analysis demonstrated 50% fusion probability at 14 weeks and 75% probability at 20 weeks (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Fusion rates did not differ significantly between C1/C2 fractures and subaxial fractures (log-rank p\u0026thinsp;=\u0026thinsp;0.18).\u003c/p\u003e\n\u003ch3\u003eTime to Radiological Fusion\u003c/h3\u003e\n\u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e: Smoking status analysis (excluding 24 patients with unknown status) revealed unexpected findings. Among 57 smokers: 24.6% (n\u0026thinsp;=\u0026thinsp;14) achieved no fusion, 22.8% (n\u0026thinsp;=\u0026thinsp;13) partial fusion, and 36.8% (n\u0026thinsp;=\u0026thinsp;21) good fusion. Among 124 non-smokers: 29.0% (n\u0026thinsp;=\u0026thinsp;36) no fusion, 27.4% (n\u0026thinsp;=\u0026thinsp;34) partial fusion, and 28.2% (n\u0026thinsp;=\u0026thinsp;35) good fusion. Overall fusion rates (good or partial combined) did not differ significantly between smokers (59.6%) and non-smokers (55.6%, χ\u0026sup2;=0.42, p\u0026thinsp;=\u0026thinsp;0.52). However, dynamic imaging analysis revealed smokers demonstrated higher rates of movement on flexion-extension radiographs (12.3%, n\u0026thinsp;=\u0026thinsp;7/57) compared to non-smokers (5.6%, n\u0026thinsp;=\u0026thinsp;7/124, χ\u0026sup2;=4.87, p\u0026thinsp;=\u0026thinsp;0.03).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSurgical Intervention\u003c/p\u003e \u003cp\u003eOverall surgical conversion rate was 22.0% (n\u0026thinsp;=\u0026thinsp;45 patients). The indications are detailed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Mean time from halo application to surgical conversion was 14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9 weeks (median 12 weeks, range 2\u0026ndash;38 weeks). Surgical conversion rates differed significantly by age group: 24.3% (9/37) in 16\u0026ndash;40 years, 27.6% (27/98) in 41\u0026ndash;65 years, and 12.7% (9/71) in \u0026gt;\u0026thinsp;65 years (p\u0026thinsp;=\u0026thinsp;0.04, chi-square test).\u003c/p\u003e \u003cp\u003eMortality\u003c/p\u003e \u003cp\u003eOverall mortality during the study period was 0.5% (n\u0026thinsp;=\u0026thinsp;1). This single mortality occurred in an 82-year-old patient with multiple comorbidities (advanced heart failure, chronic kidney disease, metastatic malignancy) who died 6 weeks after halo application from cardiovascular complications. Death was adjudicated as unrelated to halo treatment. No deaths were directly attributable to halo-related complications.\u003c/p\u003e \u003cp\u003eMultivariable Analysis of Predictors\u003c/p\u003e \u003cp\u003eMultivariable logistic regression identified independent predictors for three key outcomes (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). For complications, longer immobilization duration was associated with increased risk (OR 1.008 per day, 95% CI: 1.004\u0026ndash;1.013, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). For fusion success, traumatic etiology was associated with higher fusion rates (OR 3.24, 95% CI: 1.45\u0026ndash;7.23, p\u0026thinsp;=\u0026thinsp;0.004). For surgical conversion, subaxial fractures (OR 2.41, 95% CI: 1.18\u0026ndash;4.92, p\u0026thinsp;=\u0026thinsp;0.02), neurological deficit at presentation (OR 2.87, 95% CI: 1.42\u0026ndash;5.79, p\u0026thinsp;=\u0026thinsp;0.003), and non-traumatic etiology (OR 4.12, 95% CI: 1.76\u0026ndash;9.64, p\u0026thinsp;=\u0026thinsp;0.001) were independent predictors. Model discrimination was acceptable to good: complication model AUC-ROC 0.72, fusion model AUC-ROC 0.69, surgical conversion model AUC-ROC 0.78.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMultivariable Logistic Regression Analysis of Predictors\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eA. Predictors of Any Complication (AUC-ROC: 0.72)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor Variable\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImmobilization duration (per day)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.004\u0026ndash;1.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-application traction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.89\u0026ndash;3.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eB. Predictors of Fusion Success (AUC-ROC: 0.69)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor Variable\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTraumatic etiology (vs. non-traumatic)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.45\u0026ndash;7.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge 41\u0026ndash;65 years (vs. extremes)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.92\u0026ndash;3.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eC. Predictors of Surgical Conversion (AUC-ROC: 0.78)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor Variable\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubaxial fracture (vs. upper cervical)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.18\u0026ndash;4.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.02\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeurological deficit at presentation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.42\u0026ndash;5.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-traumatic etiology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.76\u0026ndash;9.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026thinsp;\u0026gt;\u0026thinsp;65 years (vs. \u0026lt;65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.19\u0026ndash;0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eOR odds ratio, CI confidence interval, AUC-ROC area under the receiver operating characteristic curve. All models demonstrated adequate fit by Hosmer-Lemeshow test (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Bold values indicate statistical significance (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05)\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis large retrospective cohort study of 205 adult patients over a 10-year period provides contemporary evidence regarding halo vest immobilization outcomes for cervical spine injuries at a European tertiary referral centre. Our findings demonstrate that halo immobilization remains an effective treatment modality with acceptable complication rates (37.6%), successful fusion or clinical stabilization in the majority of patients (84.4%), low surgical conversion rates (22.0%), and notably low mortality (0.5%). Critically, we identified that approximately one-quarter of patients (26.8%) achieved clinical stability sufficient for safe halo discontinuation despite absence of radiologic fusion, supporting a paradigm shift toward functional outcome assessment.\u003c/p\u003e \u003cp\u003eComplication Rates: Comparison with Literature\u003c/p\u003e \u003cp\u003eOur overall complication rate of 37.6% aligns with contemporary series. Isidro et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] reported 36% complication rate in 158 patients, while Bransford et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] documented 42% complications in 119 patients. However, our pin-site infection rate (22.4% total; 16.1% minor, 6.3% severe) is lower than several large series: Gluf et al. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] reported 29% pin-site infections, and Lind et al. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] documented 38% in elderly patients. This difference may reflect our institutional protocol emphasizing frequent pin-site care, scheduled retorquing, and early recognition with aggressive treatment of minor infections before progression.\u003c/p\u003e \u003cp\u003eNotably, we observed zero cases of neurological deterioration directly attributable to halo treatment, contrasting with 2\u0026ndash;5% rates reported in other series [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Our skull breach rate (3.4%) falls within the reported range (0\u0026ndash;9%) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The age-stratified complication analysis revealed no significant differences between age groups (p\u0026thinsp;=\u0026thinsp;0.36), contradicting the widespread belief that elderly patients experience substantially higher complication rates.\u003c/p\u003e \u003cp\u003eClinical Stability Without Radiologic Fusion: A potentially novel consideration\u003c/p\u003e \u003cp\u003eOur fusion rate of 57.6% (combining good and partial fusion) requires careful interpretation in context of our novel finding regarding clinical stability. Traditional literature focuses on radiologic fusion as the primary success metric, with reported rates varying widely: 59\u0026ndash;93% for odontoid fractures [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], 71\u0026ndash;86% for C1 fractures [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], and 63\u0026ndash;79% for subaxial injuries [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. However, our study demonstrates that 26.8% of patients with no radiologic fusion achieved clinical stability on dynamic imaging, allowing safe halo discontinuation without subsequent surgical intervention during extended follow-up (mean 18 months).\u003c/p\u003e \u003cp\u003eThis finding represents a significant paradigm shift. We propose that the appropriate success metric is not radiologic fusion per se, but rather achievement of clinical stability- defined by absence of pathological motion on dynamic imaging combined with resolution of mechanical neck pain. By this criterion, our true success rate is 84.4%, substantially higher than the 57.6% radiologic fusion rate. This distinction has important implications for patient counselling, treatment duration decisions, and definition of treatment endpoints.\u003c/p\u003e \u003cp\u003eThe concept of 'stable pseudoarthrosis' is well-established in spinal surgery literature [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], but has received limited attention in halo immobilization outcomes. Schoenfeld et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] described similar findings in type II odontoid fractures, where 27% developed fibrous union but remained asymptomatic and stable on dynamic imaging over 5-year follow-up. Our data extend this concept across all cervical fracture types and provide the largest cohort demonstrating safety of this approach.\u003c/p\u003e \u003cp\u003eMortality: Challenging Historical Perceptions\u003c/p\u003e \u003cp\u003eOur mortality rate of 0.5% (1/205) markedly contrasts with historical reports suggesting 8\u0026ndash;40% mortality associated with halo immobilization in cervical spine injuries [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Lind et al. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] reported 10% mortality in elderly patients, while Tashjian et al. [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e] documented 15% mortality in patients\u0026thinsp;\u0026gt;\u0026thinsp;65 years. However, more contemporary series have reported lower rates: Schoenfeld et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] reported 3% mortality, and Koech et al. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e] documented 2.4% in odontoid fractures.\u003c/p\u003e \u003cp\u003eSeveral factors likely explain the declining mortality trend. First, historical series often included mortality from any cause during hospitalization or follow-up, attributing deaths to halo treatment when they actually reflected baseline comorbidity burden or injury severity. Second, improved critical care, earlier mobilization protocols, aggressive deep vein thrombosis prophylaxis, and modern pulmonary care have reduced secondary complications. These findings suggest that appropriately selected patients can undergo halo immobilization with minimal mortality risk.\u003c/p\u003e \u003cp\u003eClinical Implications\u003c/p\u003e \u003cp\u003eOur findings have several important clinical implications. First, clinical stability on dynamic imaging should be considered an acceptable endpoint for halo discontinuation even in the absence of complete radiologic fusion. We recommend incorporating flexion-extension radiography at 12 weeks for patients without radiologic fusion, with consideration for halo removal if \u0026lt;3mm translation and \u0026lt;\u0026thinsp;11\u0026deg; angulation are demonstrated with absence of mechanical neck pain. Second, complications should be viewed as manageable rather than prohibitive. Pin-site infections were successfully treated in 71.7% with oral antibiotics alone. Third, patient selection should be refined based on our identified risk factors. Subaxial fractures with neurological deficit and non-traumatic aetiologies warrant closer monitoring and consideration of earlier surgical intervention.\u003c/p\u003e \u003cp\u003eLimitations\u003c/p\u003e \u003cp\u003eSeveral limitations warrant acknowledgment. First, the retrospective design limits control over confounding variables and precludes standardized assessment protocols. Selection bias is inherent, as surgical candidacy decisions were made by individual treating surgeons. Second, while radiologic fusion assessment was performed using plain radiography at routine intervals with computed tomography obtained when plain films were inconclusive, all imaging was formally reported by institutional neuroradiologists and reviewed by the treating consultant spine surgeon. Dynamic imaging measurements were primarily assessed through formal neuroradiologist reports; however, in cases where instability was noted or halo removal was considered despite incomplete fusion, measurements were verified by the senior spine surgeon using standardized measurement techniques [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. This dual assessment approach aimed to ensure consistency with established instability thresholds, though potential inter-observer variability in measurement remains a consideration. Third, we lacked standardized functional outcome measures beyond clinical stability assessment. Fourth, smoking status relied on medical record documentation, which may be incomplete or inaccurate. Fifth, fusion assessment by multiple radiologists over the 10-year period without independent blinded review may introduce variability in interpretation. Sixth, our follow-up duration (mean 18 months) may be insufficient to capture late complications or delayed failures. Finally, our single-centre experience may limit generalizability to other institutions with different patient populations or treatment protocols.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis large retrospective cohort study demonstrates that halo vest immobilization remains a safe and effective treatment modality for cervical spine injuries in adults, with 37.6% complication rate, 84.4% successful stabilization (combining radiologic fusion and clinical stability), 22.0% surgical conversion rate, and 0.5% mortality. Our key finding that 26.8% of patients achieved clinical stability sufficient for safe halo discontinuation despite absent radiologic fusion challenges traditional paradigms emphasizing radiographic union as the sole success criterion.\u003c/p\u003e \u003cp\u003eWe propose that clinical stability\u0026mdash;assessed through dynamic flexion-extension imaging combined with symptom resolution\u0026mdash;represents a more clinically relevant endpoint than radiologic fusion for halo treatment. This approach has potential to reduce prolonged immobilization duration, minimize complications from extended treatment, and improve patient satisfaction while maintaining safety. Patients with subaxial fractures, neurological deficits, or non-traumatic etiologies warrant heightened surveillance and earlier consideration of surgical intervention. With appropriate patient selection, standardized application technique, proactive complication management, and judicious use of dynamic imaging to guide treatment duration, halo vest immobilization provides a valuable non-surgical option for cervical spine stabilization across diverse patient populations and fracture patterns.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompliance with ethical standards\u003c/h2\u003e \u003cp\u003e \u003cb\u003eConflict of interest\u003c/b\u003e The authors declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthical approval\u003c/h2\u003e \u003cp\u003eThis study was performed in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments. Data was captured as part of an institution approved audit process.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eInformed consent\u003c/strong\u003e \u003cp\u003eInformed consent was waived due to the retrospective nature of the study.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors declare they have not received any funding for this research\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eKS, MBI, and OA contributed to data collection and manuscript preparation. NB and NS provided senior oversight, study design, and critical manuscript revision. All authors contributed to data interpretation and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAarabi B, Walters BC, Dhall SS et al (2013) Subaxial cervical spine injury classification systems. Neurosurg 72 Suppl 2170\u0026ndash;186. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1227/NEU.0b013e31828e37a8\u003c/span\u003e\u003cspan address=\"10.1227/NEU.0b013e31828e37a8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFehlings MG, Tetreault LA, Wilson JR et al (2017) A clinical practice guideline for the management of acute spinal cord injury: introduction, rationale, and scope. Global Spine J 7(3 Suppl):84S\u0026ndash;94S. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/2192568217703387\u003c/span\u003e\u003cspan address=\"10.1177/2192568217703387\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVaccaro AR, Koerner JD, Radcliff KE et al (2016) AOSpine subaxial cervical spine injury classification system. Eur Spine J 25(7):2173\u0026ndash;2184. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00586-015-3831-3\u003c/span\u003e\u003cspan address=\"10.1007/s00586-015-3831-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNickel VL, Perry J, Garrett A, Heppenstall M (1968) The halo. A spinal skeletal traction fixation device. J Bone Joint Surg Am 50(7):1400\u0026ndash;1409\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGluf WM, Browner CM (2007) Halo vest immobilization in acute spinal cord injury: treatment and outcomes. Spine J 7(4):444\u0026ndash;451. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.spinee.2006.07.003\u003c/span\u003e\u003cspan address=\"10.1016/j.spinee.2006.07.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGluf WM, Browner CM (2007) Halo vest immobilization in acute spinal cord injury: treatment and outcomes. Spine J 7(4):444\u0026ndash;451. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.spinee.2006.07.003\u003c/span\u003e\u003cspan address=\"10.1016/j.spinee.2006.07.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGarfin SR, Botte MJ, Waters RL, Nickel VL (1986) Complications in the use of the halo fixation device. J Bone Joint Surg Am 68(3):320\u0026ndash;325\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJeong HY, You JW, Sohn HM, Park SH (2013) Radiologic evaluation of degeneration in isthmic and degenerative spondylolisthesis. Asian Spine J 7(1):25\u0026ndash;33. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4184/asj.2013.7.1.25\u003c/span\u003e\u003cspan address=\"10.4184/asj.2013.7.1.25\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElmose SF, Andersen GO, Carreon LY, Sigmundsson FG, Andersen MO (2023) Radiological Definitions of Sagittal Plane Segmental Instability in the Degenerative Lumbar Spine - A Systematic Review. Global Spine J 13(2):523\u0026ndash;533. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/21925682221099854\u003c/span\u003e\u003cspan address=\"10.1177/21925682221099854\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBotte MJ, Byrne TP, Abrams RA, Garfin SR (1995) Halo skeletal fixation: techniques of application and prevention of complications. J Am Acad Orthop Surg 3(1):44\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5435/00124635-199501000-00006\u003c/span\u003e\u003cspan address=\"10.5435/00124635-199501000-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLind B, Sihlbom H, Nordwall A (1988) Halo-vest treatment of unstable traumatic cervical spine injuries. Spine 13(4):425\u0026ndash;432\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDormans JP, Criscitiello AA, Drummond DS, Davidson RS (1995) Complications in children managed with immobilization in a halo vest. J Bone Joint Surg Am 77(9):1370\u0026ndash;1373. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2106/00004623-199509000-00011\u003c/span\u003e\u003cspan address=\"10.2106/00004623-199509000-00011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePolin RS, Szabo T, Bogaev CA, Replogle RE, Jane JA (1996) Nonoperative management of Types II and III odontoid fractures: the Philadelphia collar versus the halo vest. Neurosurgery 38(3):450\u0026ndash;456. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00006123-199603000-00006\u003c/span\u003e\u003cspan address=\"10.1097/00006123-199603000-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHanigan WC, Powell FC, Elwood PW, Henderson JP (1993) Odontoid fractures in elderly patients. J Neurosurg 78(1):32\u0026ndash;35. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/jns.1993.78.1.0032\u003c/span\u003e\u003cspan address=\"10.3171/jns.1993.78.1.0032\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeybold EA, Bayley JC (1998) Functional outcome of surgically and conservatively managed dens fractures. Spine 23(17):1837\u0026ndash;1845. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-199809010-00006\u003c/span\u003e\u003cspan address=\"10.1097/00007632-199809010-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVaccaro AR, Hulbert RJ, Patel AA, Fisher C, Dvorak M, Lehman RA Jr, Anderson P, Harrop J, Oner FC, Arnold P, Fehlings M, Hedlund R, Madrazo I, Rechtine G, Aarabi B, Shainline M (2007) The subaxial cervical spine injury classification system: a novel approach to recognize the importance of morphology, neurology, and integrity of the disco-ligamentous complex. Spine 32(21):2365\u0026ndash;2374. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0b013e3181557b92\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e3181557b92\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMajercik S, Tashjian RZ, Biffl WL, Harrington DT, Cioffi WG (2005) Halo vest immobilization in the elderly: a death sentence? J Trauma 59(2):350\u0026ndash;356. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/01.ta.0000174671.07664.7c\u003c/span\u003e\u003cspan address=\"10.1097/01.ta.0000174671.07664.7c\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePlatzer P, Thalhammer G, Sarahrudi K, Kovar F, V\u0026eacute;csei V, Gaebler C (2007) Nonoperative management of odontoid fractures using a halo thoracic vest. Neurosurgery 61(3):522\u0026ndash;529. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1227/01.NEU.0000290900.95085.A1\u003c/span\u003e\u003cspan address=\"10.1227/01.NEU.0000290900.95085.A1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIsidro S, Molinari R, Ikpeze T, Hern\u0026aacute;ndez C, Mahmoudi M, Mesfin A (2019) Outcomes of halo immobilization for cervical spine fractures. Global Spine J 9(5):521\u0026ndash;526. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/2192568218808293\u003c/span\u003e\u003cspan address=\"10.1177/2192568218808293\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBransford R, Falicov A, Nguyen Q, Chapman J (2009) Unplanned reoperation after surgery for cervical fracture/dislocation. Spine 34(1):35\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0b013e31818e2d8b\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e31818e2d8b\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGluf WM, Schmidt MH, Apfelbaum RI (2005) Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 191 adult patients. J Neurosurg Spine 2(2):155\u0026ndash;163. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/spi.2005.2.2.0155\u003c/span\u003e\u003cspan address=\"10.3171/spi.2005.2.2.0155\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLind B, Nordwall A, Sihlbom H (1987) Odontoid fractures treated with halo-vest. Spine 12(2):173\u0026ndash;177. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-198703000-00015\u003c/span\u003e\u003cspan address=\"10.1097/00007632-198703000-00015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLennarson PJ, Mostafavi H, Traynelis VC, Walters BC (2000) Management of type II dens fractures: a case-control study. Spine 25(10):1234\u0026ndash;1237. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-200005150-00008\u003c/span\u003e\u003cspan address=\"10.1097/00007632-200005150-00008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim SM, Lim TJ, Paterno J, Sasso RC (2012) A biomechanical comparison of three surgical approaches in bilateral subaxial cervical facet dislocation. J Neurosurg Spine 17(3):230\u0026ndash;235. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/2012.5.SPINE1232\u003c/span\u003e\u003cspan address=\"10.3171/2012.5.SPINE1232\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlover A, Zakaria R, May P, Barrett C (2013) Overtightening of halo pins resulting in intracranial penetration, pneumocephalus, and epileptic seizure. Int J Spine Surg 7:e42\u0026ndash;e44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijsp.2013.01.004\u003c/span\u003e\u003cspan address=\"10.1016/j.ijsp.2013.01.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKostuik JP, Carlson AN, Esses SI, Penta F (1996) Posterior arthrodesis for acquired spondylolisthesis. Spine 21(18):2148\u0026ndash;2156. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-199609150-00014\u003c/span\u003e\u003cspan address=\"10.1097/00007632-199609150-00014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eApfelbaum RI, Lonser RR, Veres R, Casey A (2000) Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 93(2 Suppl):227\u0026ndash;236. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/spi.2000.93.2.0227\u003c/span\u003e\u003cspan address=\"10.3171/spi.2000.93.2.0227\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJulien TD, Frankel B, Traynelis VC, Ryken TC (2000) Evidence-based analysis of odontoid fracture management. Neurosurg Focus 8(6):e1. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/foc.2000.8.6.1\u003c/span\u003e\u003cspan address=\"10.3171/foc.2000.8.6.1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChapman J, Smith JS, Kopjar B, Vaccaro AR, Arnold P, Shaffrey CI, Fehlings MG (2010) The AOSpine North America Geriatric Odontoid Fracture Mortality Study: a retrospective review of mortality outcomes for operative versus nonoperative treatment of 322 patients with long-term follow-up. Spine 35(22):1938\u0026ndash;1943. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0b013e3181eadd31\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e3181eadd31\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHadley MN, Dickman CA, Browner CM, Sonntag VK (1988) Acute traumatic atlas fractures: management and long term outcome. Neurosurgery 23(1):31\u0026ndash;35. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1227/00006123-198807000-00006\u003c/span\u003e\u003cspan address=\"10.1227/00006123-198807000-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDickman CA, Greene KA, Sonntag VK (1996) Injuries involving the transverse atlantal ligament: classification and treatment guidelines based upon experience with 39 injuries. Neurosurgery 38(1):44\u0026ndash;50. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00006123-199601000-00012\u003c/span\u003e\u003cspan address=\"10.1097/00006123-199601000-00012\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZdeblick TA, Phillips FM (2003) Interbody cage devices. Spine 28(15 Suppl). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/01.BRS.0000076895.52418.71\u003c/span\u003e\u003cspan address=\"10.1097/01.BRS.0000076895.52418.71\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. S2-S7\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchoenfeld AJ, Bono CM, Reichmann WM, Warholic N, Wood KB, Losina E, Katz JN, Harris MB (2011) Type II odontoid fractures of the cervical spine: do treatment type and medical comorbidities affect mortality in elderly patients? Spine 36(11):879\u0026ndash;885. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0b013e3181e8e77c\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e3181e8e77c\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndersen T, Christensen FB, Laursen M, H\u0026oslash;y K, Hansen ES, B\u0026uuml;nger C (2001) Smoking as a predictor of negative outcome in lumbar spinal fusion. Spine 26(23):2623\u0026ndash;2628. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-200112010-00018\u003c/span\u003e\u003cspan address=\"10.1097/00007632-200112010-00018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlassman SD, Anagnost SC, Parker A, Burke D, Johnson JR, Dimar JR (2000) The effect of cigarette smoking and smoking cessation on spinal fusion. Spine 25(20):2608\u0026ndash;2615. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00007632-200010150-00011\u003c/span\u003e\u003cspan address=\"10.1097/00007632-200010150-00011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSantiago P, Fessler RG (2014) Thoracic and lumbar fractures. Neurosurg Clin N Am 25(4):717\u0026ndash;721. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.nec.2014.07.003\u003c/span\u003e\u003cspan address=\"10.1016/j.nec.2014.07.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAckland HM, Cooper DJ, Malham GM, Kossmann T (2007) Factors predicting cervical collar-related decubitus ulceration in major trauma patients. Spine 32(4):423\u0026ndash;428. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/01.brs.0000255100.13898.0e\u003c/span\u003e\u003cspan address=\"10.1097/01.brs.0000255100.13898.0e\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHorn EM, Theodore N, Feiz-Erfan I, Lekovic GP, Dickman CA, Sonntag VK (2006) Complications of halo fixation in the elderly. J Neurosurg Spine 5(1):46\u0026ndash;49. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/spi.2006.5.1.46\u003c/span\u003e\u003cspan address=\"10.3171/spi.2006.5.1.46\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePepin JW, Bourne RB, Hawkins RJ (1985) Odontoid fractures, with special reference to the elderly patient. Clin Orthop Relat Res 193:178\u0026ndash;183\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTashjian RZ, Majercik S, Biffl WL, Palumbo MA, Cioffi WG (2006) Halo-vest immobilization increases early morbidity and mortality in elderly odontoid fractures. J Bone Joint Surg Am 88(9):2278\u0026ndash;2282. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2106/JBJS.E.01197\u003c/span\u003e\u003cspan address=\"10.2106/JBJS.E.01197\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBednar DA, Parikh J, Hummel J (1995) Management of type II odontoid process fractures in geriatric patients; a prospective study of sequential cohorts with attention to survivorship. J Spinal Disord 8(2):166\u0026ndash;169\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTraynelis VC, Marano GD, Dunker RO, Kaufman HH (1992) Traumatic atlanto-occipital dislocation. Case report. J Neurosurg 76(5):880\u0026ndash;884. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3171/jns.1992.76.5.0880\u003c/span\u003e\u003cspan address=\"10.3171/jns.1992.76.5.0880\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoech F, Ackland HM, Varma DK, Williamson OD, Malham GM (2008) Nonoperative management of type II odontoid fractures in the elderly. Spine 33(26):2881\u0026ndash;2886. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/BRS.0b013e31818d5407\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e31818d5407\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Halo vest, Cervical spine fracture, Complications, Fusion, Clinical stability, Dynamic imaging","lastPublishedDoi":"10.21203/rs.3.rs-8681118/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8681118/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eHalo vest immobilization remains a widely utilized non-surgical treatment for cervical spine fractures. However, comprehensive data on complication rates, fusion outcomes, and factors influencing treatment success are limited, particularly regarding clinical decision-making when radiologic fusion is incomplete.\u003c/p\u003e\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo evaluate complication rates, fusion outcomes, predictive factors for treatment success, and clinical decision-making patterns in adult patients undergoing halo vest immobilization for cervical spine injuries.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis retrospective cohort study analysed 205 adult patients (mean age 56.6\u0026thinsp;\u0026plusmn;\u0026thinsp;16.6 years; 62.4% male) treated with halo vest immobilization for cervical spine injuries at a tertiary spine centre from 2012\u0026ndash;2022. Patient demographics, fracture characteristics, comorbidities, smoking status, complications, and fusion outcomes were recorded. Statistical analysis included chi-square tests, Mann-Whitney U tests, and multivariable logistic regression to identify predictors of complications, fusion success, and surgical intervention. Kaplan-Meier survival analysis assessed time to fusion.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eFracture distribution included C2 (36%), subaxial cervical spine (42%), C1/C2 combined (12%), and C1 alone (7%). Mean duration of halo immobilization was 169.9\u0026thinsp;\u0026plusmn;\u0026thinsp;92.3 days. Complications occurred in 37.6% of patients, with pin-site infection being most common (minor: 16.1%, severe: 6.3%). Complete or partial fusion was achieved in 57.6% of patients (95% CI: 50.6\u0026ndash;64.3%), while 26.8% showed no radiologic fusion but were deemed clinically stable for halo removal based on dynamic imaging and absence of neck pain. Younger age (41\u0026ndash;65 years) was associated with longer immobilization duration (206 days vs. 114 days in patients\u0026thinsp;\u0026gt;\u0026thinsp;65, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Smoking status showed no significant association with fusion rates (p\u0026thinsp;=\u0026thinsp;0.42) but was associated with increased movement on dynamic imaging (12.3% vs. 5.7% in non-smokers, p\u0026thinsp;=\u0026thinsp;0.03). The surgical conversion rate was 22.0%, with non-union (24.4% of surgical cases), progression of instability (24.4%), and infection requiring operative management (22.2%) being the primary indications. Overall mortality was 0.5% (n\u0026thinsp;=\u0026thinsp;1).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eHalo vest immobilization remains an effective treatment modality for cervical spine injuries in adults with acceptable complication rates and low mortality. Clinical stability assessed through dynamic flexion-extension imaging provides a safe criterion for discontinuing halo immobilization in approximately one-quarter of patients despite incomplete radiologic fusion. This finding supports a paradigm shift toward functional outcome assessment rather than strict reliance on static radiologic fusion criteria. Younger patients and those with complex fracture patterns require longer immobilization periods.\u003c/p\u003e","manuscriptTitle":"Outcomes and Complications of Halo Vest Immobilization in Adults with Cervical Spine Injuries: A 10-Year Retrospective Cohort Study In a Tertiary UK Centre","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-10 14:43:54","doi":"10.21203/rs.3.rs-8681118/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7160fcfd-6f97-4c9d-82e4-c2e6f5bef44c","owner":[],"postedDate":"February 10th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-03T08:42:19+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-10 14:43:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8681118","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8681118","identity":"rs-8681118","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}