Association between post-operative mobility restrictions and acute colonic pseudo-obstruction after spinal fixation in major trauma patients: a retrospective cohort study

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A possible contributor to ACPO development is impaired mobility. Major trauma patients, particularly those with spinal trauma, are at risk of prolonged mobility restrictions. The aim of this study was to assess the association between impaired mobility and the development of ACPO in major trauma patients undergoing acute thoraco-lumbar spinal fixation. Methods A retrospective cohort study involving major trauma patients admitted to a tertiary trauma facility was performed. The Hospital Trauma Registry was utilised to identify consecutive major trauma patients having urgent thoraco-lumbar spinal fixation. ACPO was defined as dilation of the transverse colon > 6cm or caecum > 9cm without mechanical cause. Immobility was defined by proxy as surgeon-prescribed mobility restrictions. Analysis was performed using multivariable logistic regression. Results ACPO occurred in 34 of 454 patients studied (7.5%). Colonoscopic decompression was required twice. Neostigmine and surgical resection were not required. There was no ACPO-related mortality. On multivariable regression, adjusted for confounding variables, post-operative mobility restrictions were associated with a three-fold increase in odds of ACPO (Odds Ratio 3.0; 95% confidence interval 1.1–8.2, P = 0.03). Conclusion ACPO was a common, although low-morbidity complication in this cohort. Surgically-prescribed mobility restrictions were associated with higher odds of ACPO in major trauma patients having thoraco-lumbar spinal fixation. Attention should be given to early mobilisation, where possible, in these patients. Acute colonic pseudo-obstruction Ogilvie Syndrome Spinal Fracture Neostigmine mobility Media Summary In this retrospective cohort study, post-operative mobility restrictions were associated with development of acute colonic pseudo-obstruction in major trauma patients undergoing spinal fixation, after adjusting for likely confounders. Background Acute colonic pseudo-obstruction (ACPO) is a poorly understood phenomenon that may complicate surgical and trauma care. The underlying pathophysiology is generally considered to be a relative excess of sympathetic over parasympathetic drive to the left colon, with subsequent non-function and progressive colonic distension [ 1 ], [ 2 ]. Untreated, the colon may continue to distend until ischemic perforation occurs, with potentially grave results. Trauma is associated with higher rates of ACPO development. The incidence of ACPO following elective surgery has been reported at 0.04–0.22% following spinal fixation and joint replacement in large-scale registry studies [ 3 ]–[ 5 ]. In contrast, ACPO occurrence of 1.6% [ 6 ], 2.7% [ 7 ] and 7.5% [ 8 ] of were reported following emergent hip, pelvic and spinal fixation respectively. The reasons for the higher incidence of ACPO following spinal trauma are not currently clear. Multi-trauma patients are exposed to a range of potential risk factors including opiate exposure, prolonged fasting and potential electrolyte derangement [ 1 ], [ 4 ], [ 5 ], [ 9 ]. Spinal trauma itself has been implicated in a causative role via disruption of the autonomic pathways supplying the colon [ 10 ]. Finally, multitrauma patients with spinal fracture may be poorly mobile, despite spinal fixation, for prolonged periods. Reduced mobility is frequently described as a risk factor for ACPO, although the evidence supporting this appears limited to retrospective series with variable definitions of reduced mobility, that did not control for confounding variables [ 11 ]–[ 13 ]. We hypothesised that relative immobility was one of the key drivers to the development of ACPO in the setting of thoracolumbar spinal trauma requiring fixation. The aim of this study was to assess the association between post-operative immobility and ACPO in a cohort of major trauma patients undergoing acute thoraco-lumbar spinal fixation after thoracic or lumbar trauma, adjusting for the potential confounding effects of other variables. Methods Ethics approval was granted by the local Hospital Ethics Review Board (QA2022053). The Hospital Trauma Registry (H-TR) was utilised to identify all cases of major trauma with unstable thoracic or lumbar spinal fracture requiring fixation between November 2015 and December 2021. The hospital is a tertiary trauma facility that treats approximately half of the major trauma of the state of Victoria, Australia. The H-TR is a comprehensive database that includes all major trauma presenting to the hospital. It is maintained prospectively by trained health information officers. The H-TR includes details on the mechanism, injuries, timing and nature of interventions, comorbidity status and outcomes, including mortality and length of stay. Additional data were extracted from patient charts and cross-referenced to the registry data. Surgical intervention details, symptomology, radiological findings, interventions and progress were extracted from patient medical records. 10% of the data was recollected for quality control. Definitions The principal exposure of interest was mobility restrictions prescribed peri-operatively. This was defined as any weight-bearing limitation through the lower limbs prescribed by surgeons in operative notes at the time of the spinal fixation. For example, touch weight-bearing or non-weight-bearing would both be recorded as mobility restriction. Major trauma was defined using the Victorian major trauma criteria [ 14 ]. This included: Cases with mortal injury; an Injury Severity Score (ISS) > 12; Intensive Care Unit admission for more than 24 hours; or urgent surgery to the head, chest, abdomen, spine or pelvis within 48 hours. The primary outcome, ACPO, was defined as symptomatic colon dilatation (transverse colon > 6cm or caecum > 9cm) in the absence of distal mechanical obstruction or identifiable cause of functional obstruction as previously described [ 15 ], [ 16 ]. Imaging included both abdominal X-ray (AXR) and computed tomography (CT). Maximal diameter was measured using imaging software if not reported. Post-operative analgesia type was categorised as patient-controlled intravenous opiate use (PCA), epidural anaesthesia and enteral analgesia. For analysis, this was dichotomised as PCA use versus non-use. Level of thoraco-lumbar fracture was categorised as thoracic or lumbar depending on predominant distribution and spinal surgical approach was defined as posterior or other (comprising anterior or circumferential). Injury pattern was considered as an important potential confounder. This was categorised into two summary variables: Major non-orthopaedic injury – including traumatic brain injury; major chest injury (organ injury severity score > 2) and abdominal solid organ injury or laparotomy; and major non-spinal orthopaedic injury , including pelvic and limb fracture. Soft tissue injuries were not recorded. The primary outcome was development of ACPO according to the above definition. Additional outcomes included length of hospital stay, interventions required and mortality rates. Statistical analysis All statistical analysis was performed using STATA (Stata 17, Statacorp, TX USA). Baseline data were presented as counts, percentages, median values and interquartile ranges. Regression analysis results were presented as odds ratio, 95% confidence intervals (CI) and p-values. Univariable logistic regression analysis was performed of main variables with odds of development of ACPO as the main outcome of interest. A Directed Acyclic Graph (DAG) was used to assess which variables could be considered as potentially confounding variables in the association between mobility status and development of ACPO. The primary variables identified as potential confounders including age and gender, ASA score, injury severity score, injury patterns (as reflected in the combined variables of major non-orthopaedic injury and non-spinal orthopaedic injury) as well as opiate exposure, reflected in PCA use, and spinal cord injury. Multivariable logistic regression was performed with mobility restrictions as the exposure of interest and APCO as the outcome of interest, adjusted for the potentially confounding effects of the covariables selected from the DAG. Cases with missing values from these variables were not included in the multivariable regression. Results The H-TR identified 460 patients with major trauma undergoing thoracolumbar spinal arthrodesis. Six cases were excluded: Three did not undergo thoracolumbar spinal arthrodesis; one patient underwent delayed repair in a subsequent admission and two patients were missing clinical notes. Of the subsequent 454, A total of 34 cases of ACPO were identified (7.5%). Dilated colon was seen on imaging in two patients but not considered as ACPO, due to diagnoses of clostridium difficile colitis and mechanical obstruction respectively. Post-operative mobility status was not documented in three patients. No mortality from ACPO was seen. No patients required surgery, and two patients underwent colonoscopic decompression. The remainder were successfully treated medically, including enema and rectal tube utilisation. Neostigmine was not used. Full details on treatment have been reported elsewhere [ 8 ]. Demographics and baseline comparisons are reported in Table 1 . Age, gender, ASA score and comorbidity status were similar across the two groups. However, patients with mobility restrictions prescribed tended to have higher ISS and higher rates of associated injuries, including chest wall, abdominal and other fractures. Spinal fracture distribution and surgical management were broadly similar. In addition, length of stay was substantially longer in patients with prescribed mobility restrictions (median 19 days versus 9 days). Table 1 Demographics No mobility Restrictions Mobility restrictions Number 375 76 Median Age (IQR) 45 (27–61) 46 (30–60) Female gender 98 (26.1%) 18 (23.7%) Median ASA (IQR) 1 (0–1) 1 (0–1) No Comorbidities 37.6% (158) 41.2% (14) Median ISS (IQR) 14 (10–21) 25.5 (18–38) Injuries Spinal cord injury 40 (10.7%) 13 (17.1%) Major chest wall injury 127 (33.9%) 44 (57.9%) Solid organ abdominal injury 32 (8.5%) 18 (23.7%) Trauma laparotomy 24 (6.4%) 7 (9.2%) Major non-orthopaedic injury 206 (54.9%) 25 (32.9%) Major non-spinal orthopaedic injury 111 (29.6%) 73 (96.1%) Thoracic fracture 225 (60.2%) 49 (65.3%) Median number of fractures (IQR) 1 (1–2) 1 (1–2) Median levels of fusion (IQR) 5 (4–6) 5 (4–6) Posterior spinal approach 327 (87.4%) 67 (88.2%) Median duration of surgery (min; IQR) 107 (83–135) 121 (92–164) PCA use 303 (80.8%) 61 (80.3%) Median hospital length of stay (Days, IQR) 9 (6–14) 19 (11–27) ACPO occurrence (N,%) 22 (5.9%) 12 (15.8%) Univariable regression The findings of univariable regression are reported in Table 2 . Post-operative mobility restrictions were associated with an OR of 3.0 (95% CI 1.4–6.0, P < 0.01) for the development of ACPO. There was no evidence of an association between ACPO development and age, ISS score, fracture level, surgical approach or gender. PCA use had a strong correlation with ACPO development, however this was limited by very low numbers. A single patient developed ACPO in the absence of PCA use, making this data difficult to interpret. Table 2 Univariable logistic regression for development of ACPO Odds ratio for ACPO (95% CI) P value N without ACPO N with ACPO Number 420 34 Female gender 0.7 (0.3–1.7) 0.49 109 (29%) 7 (20.6%) ASA Score 1 2 3 4 Ref 4.5 (1–20) 2.4 (0.5–11.6) 2.3 (0.4–14.5) 0.05 0.30 0.37 65 (19.1%) 130 (38.1%) 97 (28.4%) 42 (12.3%) 2 (6.7%) 18 (60%) 7 (23.3%) 3 (10%) Level of fracture Thoracic Ref 258 (61.7%) 17 (50%) Lumbar 1.6 (0.8–3.3) 0.18 160 (38.3%) 17 (50%) Surgical approach Anterior or circumferential Ref 53 (12.7%) 4 (11.8%) Posterior approach 1.1 (0.4–3.2) 0.88 366 (87.4%) 30 (88.2%) ISS Categories ISS 25 Ref 1.9 (0.7–5.3) 1.9 (0.6–5.9) 0.20 0.30 104 (24.8%) 226 (53.8%) 90 (21.4%) 5 (14.7%) 21 (76.5%) 8 (23.5%) Major non-orthopaedic injury 1.8 (0.9–3.6) 0.12 200 (47.6%) 21 (61.8%) Spinal cord injury 2.6 (1.1 -6) 0.03 45 (10.7%) 8 (23.5%) Major non-spinal orthopaedic injury 1.7 (0.8–3.4) 0.15 169 (40.2%) 18 (52.9%) Post-operative mobility restrictions 3.0 (1.4–6.4) < 0.01 64 (15.4%) 12 (35.3%) PCA use (vs non-use) 8.45 (1.1–62.7) 0.04 332 (79.1%) 33 (97.1%) Multivariable regression Multivariable analysis was performed using logistic regression, controlling for potential confounders as identified in the DAG. ASA score was initially planned for inclusion in the model, though was poorly recorded, such that 80 missing values were identified. To avoid excessive reduction in sample size, this was excluded from the model. After adjusting for the effects of age, gender, injury severity score and injury patterns, PCA use and spinal cord injury, post-operative mobility restrictions retained evidence of an association with ACPO (OR 3.0, 95% CI: 1.1–8.2, P = 0.03). PCA use was noted as a significant contributor to ACPO development in this model, however as noted previously, the low numbers produced very wide confidence intervals that were not reliable. A sensitivity analysis was performed excluding PCA use. There was no major change to the effect of mobility restrictions (OR 3.2, 95% CI: 1.2–8.6, P = 0.02). A second sensitivity analysis was performed including ASA score, with only minimal change to the effect of mobility restrictions (OR 3.2, 95% CI 1.0–9.9, P = 0.04, N = 361). Spinal cord injury had some evidence of association with ACPO development on univariable logistic regression (OR 2.5, 95% CI: 1.1–6.0, P = 0.03), however had less evidence of association on multivariable logistic regression analysis (OR 2.5, 95% CI: 1.0–6.5, P = 0.06). Table 3 Multivariable logistic regression for effect of mobility restrictions on ACPO development, after adjusting for gender, age, ISS, other injuries and PCA usage Variable OR (95% CI) P Value Post-operative mobility restriction 3.0 (1.1–8.2) 0.03 Female Gender 0.8 (0.3–1.9) 0.58 Age Categories 18– 34 years 35–54 years 55 years + Ref 1.3 (0.6–3.1) 0.8 (0.3–2.2) 0.53 0.69 ISS Categories ISS 25 Ref 1.2 (0.4–3.6) 0.7 (0.1–3) 0.76 0.60 Major non-orthopaedic injury 1.8 (0.8–4.2) 0.18 Spinal cord injury 2.5 (0.97–6.5) 0.06 Major non-spinal orthopaedic injury .01 (0.4–2.6) 0.99 PCA use 8.4 (1.1–64.8) 0.04 N = 450. Pseudo R 2 = 0.07. Discussion ACPO in this population of major trauma patients undergoing urgent spinal fixation was a relatively common but low-morbidity complication. No mortality was seen from ACPO, and no patient required surgery. This was less severe than expected, but not dissimilar to other contemporaneous studies [ 17 ]. In this study, reduced mobility, represented by mobility restrictions prescribed by surgeons at the time of spinal surgery, was associated with an approximately three-fold increased risk of ACPO. To our knowledge, this is the first report of a relationship between reduced mobility and ACPO after adjusting for potentially confounding variables. This provides further support to the hypothesis that impaired mobility contributes to ACPO development. However, the pathophysiologic mechanisms behind this are unknown. Immobility has certainly been linked to constipation [ 18 ], though even there the mechanism is not yet understood. There remains considerable room for research to understand the pathophysiology underlying ACPO. The chief limitation to this study relates to defining and recording reduced mobility. We used a proxy measurement of prescribed, post-operative mobility restrictions to provide a standardised measure. However, this does not consider gradations in degree of mobility, and nor does it necessarily reflect actual mobility observed. Non-compliance with mobility recommendations (whether encouraging or limiting activity) reduces the clinical accuracy of this proxy measure. Other studies that have reported on post-operative mobility have also described poor mobility in vague terms, such as slow progression relative to a standard physiotherapy reference [ 11 ], or ‘delay to mobilisation’ [ 12 ]. Improved precision in the measurement of mobility would likely require a prospective study with dedicated assessment of mobility each day. In addition, whilst all attempts were made to identify and reduce confounding via DAG and multivariable logistic regression, residual bias remains a potential weakness in this retrospective cohort. One potential residual confounder is opiate exposure. Numerous studies have linked opiate exposure, including PCA use, with ACPO development [ 6 ], [ 9 ], [ 19 ]–[ 21 ]. In this study, opiate exposure could only be recorded via the mode of delivery, such as PCA use. Here, the single event that occurred without a PCA makes interpreting data difficult and resulted in very broad confidence intervals. Direct measurement of opiate intake via a prospective study design would enable more accurate comparison. Nonetheless, minimising opiate exposure has extensive advantages and should be promoted. Spinal cord injury is a second potential variable confounding the relationship between ACPO and mobility restrictions. The literature has not previously reported a direct link between spinal cord injury and ACPO development, though changes to colonic function (including constipation and incontinence) are documented [ 22 ]. Mechanistically, spinal cord injury could plausibly contribute to ACPO development either via disruption of autonomic reflex pathways or via the associated immobility that may occur as a result [ 10 ]. There was little evidence of effect on multivariable regression analysis. However, this study lacked power for this factor, and a larger sample size may be required for precision. Ideally, a prospective study would be performed to evaluate all of these risk factors, with attention to accurate recording of actual mobility, forms and dosages of opiates and other analgesia used. This would generate a more accurate assessment of contributing aetiology. In the meantime, strategies to reduce these risk factors are in line with best practice and should be pursued. Conclusion ACPO was a relatively common but low-morbidity complication of emergent surgical fixation of the thoracic or lumbar spine following trauma, occurring in 7.5%. Surgeon-prescribed mobility restrictions were associated with a threefold increase in ACPO development in multivariable analysis, controlling for age, gender, injury severity score, PCA use, injury pattern and spinal cord injury. Consideration to minimisation of mobility restrictions and earlier post-operative mobilisation, where feasible, may help reduce rates of ACPO development. Minimisation of intravenous opiate use may also be beneficial. Further research should focus on these areas, ideally through prospective methods, to further evaluate individual risk contribution with the goal of preventing ACPO. Declarations Conflict of Interest Disclosure : There is no conflict of interest to report Funding Disclosure: No funding was received for this research. 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McCormick, A. Skandarajah, and T. Cade, “Risk factors for acute colonic pseudo-obstruction after caesarean section: A retrospective case-control study.,” Aust. N. Z. J. Obstet. Gynaecol. , vol. 63, no. 1, pp. 86–92, Feb. 2023, doi: 10.1111/ajo.13583. G. M. Rodriguez and D. R. Gater, “Neurogenic Bowel and Management after Spinal Cord Injury: A Narrative Review.,” J. Pers. Med. , vol. 12, no. 7, p. 1141, Jul. 2022, doi: 10.3390/jpm12071141. 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. 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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-3874636","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":267792890,"identity":"5d322ab8-c394-426f-8821-ca22cd0f34a4","order_by":0,"name":"James Patrick Carroll","email":"data:image/png;base64,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","orcid":"","institution":"Royal Melbourne Hospital","correspondingAuthor":true,"prefix":"","firstName":"James","middleName":"Patrick","lastName":"Carroll","suffix":""},{"id":267792891,"identity":"3aa28e56-9245-4f73-b685-c0232ae0807d","order_by":1,"name":"Ian Hayes","email":"","orcid":"","institution":"Royal Melbourne Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ian","middleName":"","lastName":"Hayes","suffix":""},{"id":267792892,"identity":"e225d16a-2d46-4d46-850c-11f1d852a217","order_by":2,"name":"David Read","email":"","orcid":"","institution":"Royal Melbourne Hospital","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Read","suffix":""}],"badges":[],"createdAt":"2024-01-18 04:29:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3874636/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3874636/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":65953025,"identity":"f05b80e0-0e14-4c9a-b08d-d9251895d867","added_by":"auto","created_at":"2024-10-04 21:31:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":616850,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3874636/v1/392b0b09-1046-4005-8ea0-819c85cbfffd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Association between post-operative mobility restrictions and acute colonic pseudo-obstruction after spinal fixation in major trauma patients: a retrospective cohort study","fulltext":[{"header":"Media Summary","content":"\u003cp\u003e\u0026nbsp;In this retrospective cohort study, post-operative mobility restrictions were associated with development of acute colonic pseudo-obstruction in major trauma patients undergoing spinal fixation, after adjusting for likely confounders.\u003c/p\u003e"},{"header":"Background","content":"\u003cp\u003eAcute colonic pseudo-obstruction (ACPO) is a poorly understood phenomenon that may complicate surgical and trauma care. The underlying pathophysiology is generally considered to be a relative excess of sympathetic over parasympathetic drive to the left colon, with subsequent non-function and progressive colonic distension [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Untreated, the colon may continue to distend until ischemic perforation occurs, with potentially grave results.\u003c/p\u003e \u003cp\u003eTrauma is associated with higher rates of ACPO development. The incidence of ACPO following elective surgery has been reported at 0.04\u0026ndash;0.22% following spinal fixation and joint replacement in large-scale registry studies [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In contrast, ACPO occurrence of 1.6% [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], 2.7% [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and 7.5% [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] of were reported following emergent hip, pelvic and spinal fixation respectively.\u003c/p\u003e \u003cp\u003eThe reasons for the higher incidence of ACPO following spinal trauma are not currently clear. Multi-trauma patients are exposed to a range of potential risk factors including opiate exposure, prolonged fasting and potential electrolyte derangement [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Spinal trauma itself has been implicated in a causative role via disruption of the autonomic pathways supplying the colon [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Finally, multitrauma patients with spinal fracture may be poorly mobile, despite spinal fixation, for prolonged periods. Reduced mobility is frequently described as a risk factor for ACPO, although the evidence supporting this appears limited to retrospective series with variable definitions of reduced mobility, that did not control for confounding variables [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe hypothesised that relative immobility was one of the key drivers to the development of ACPO in the setting of thoracolumbar spinal trauma requiring fixation. The aim of this study was to assess the association between post-operative immobility and ACPO in a cohort of major trauma patients undergoing acute thoraco-lumbar spinal fixation after thoracic or lumbar trauma, adjusting for the potential confounding effects of other variables.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eEthics approval was granted by the local Hospital Ethics Review Board (QA2022053). The Hospital Trauma Registry (H-TR) was utilised to identify all cases of major trauma with unstable thoracic or lumbar spinal fracture requiring fixation between November 2015 and December 2021. The hospital is a tertiary trauma facility that treats approximately half of the major trauma of the state of Victoria, Australia. The H-TR is a comprehensive database that includes all major trauma presenting to the hospital. It is maintained prospectively by trained health information officers. The H-TR includes details on the mechanism, injuries, timing and nature of interventions, comorbidity status and outcomes, including mortality and length of stay. Additional data were extracted from patient charts and cross-referenced to the registry data. Surgical intervention details, symptomology, radiological findings, interventions and progress were extracted from patient medical records. 10% of the data was recollected for quality control.\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ch2\u003eDefinitions\u003c/h2\u003e\n\u003cp\u003eThe principal exposure of interest was mobility restrictions prescribed peri-operatively. This was defined as any weight-bearing limitation through the lower limbs prescribed by surgeons in operative notes at the time of the spinal fixation. For example, touch weight-bearing or non-weight-bearing would both be recorded as mobility restriction.\u003c/p\u003e\n\u003cp\u003eMajor trauma was defined using the Victorian major trauma criteria [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. This included: Cases with mortal injury; an Injury Severity Score (ISS)\u0026thinsp;\u0026gt;\u0026thinsp;12; Intensive Care Unit admission for more than 24 hours; or urgent surgery to the head, chest, abdomen, spine or pelvis within 48 hours.\u003c/p\u003e\n\u003cp\u003eThe primary outcome, ACPO, was defined as symptomatic colon dilatation (transverse colon\u0026thinsp;\u0026gt;\u0026thinsp;6cm or caecum\u0026thinsp;\u0026gt;\u0026thinsp;9cm) in the absence of distal mechanical obstruction or identifiable cause of functional obstruction as previously described [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e], [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]. Imaging included both abdominal X-ray (AXR) and computed tomography (CT). Maximal diameter was measured using imaging software if not reported.\u003c/p\u003e\n\u003cp\u003ePost-operative analgesia type was categorised as patient-controlled intravenous opiate use (PCA), epidural anaesthesia and enteral analgesia. For analysis, this was dichotomised as PCA use versus non-use. Level of thoraco-lumbar fracture was categorised as thoracic or lumbar depending on predominant distribution and spinal surgical approach was defined as posterior or other (comprising anterior or circumferential). Injury pattern was considered as an important potential confounder. This was categorised into two summary variables: \u003cem\u003eMajor non-orthopaedic injury\u003c/em\u003e \u0026ndash; including traumatic brain injury; major chest injury (organ injury severity score\u0026thinsp;\u0026gt;\u0026thinsp;2) and abdominal solid organ injury or laparotomy; and \u003cem\u003emajor non-spinal orthopaedic injury\u003c/em\u003e, including pelvic and limb fracture. Soft tissue injuries were not recorded.\u003c/p\u003e\n\u003cp\u003eThe primary outcome was development of ACPO according to the above definition. Additional outcomes included length of hospital stay, interventions required and mortality rates.\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003eStatistical analysis\u003c/h2\u003e\n \u003cp\u003eAll statistical analysis was performed using STATA (Stata 17, Statacorp, TX USA).\u003c/p\u003e\n \u003cp\u003eBaseline data were presented as counts, percentages, median values and interquartile ranges. Regression analysis results were presented as odds ratio, 95% confidence intervals (CI) and p-values. Univariable logistic regression analysis was performed of main variables with odds of development of ACPO as the main outcome of interest.\u003c/p\u003e\n \u003cp\u003eA Directed Acyclic Graph (DAG) was used to assess which variables could be considered as potentially confounding variables in the association between mobility status and development of ACPO. The primary variables identified as potential confounders including age and gender, ASA score, injury severity score, injury patterns (as reflected in the combined variables of major non-orthopaedic injury and non-spinal orthopaedic injury) as well as opiate exposure, reflected in PCA use, and spinal cord injury.\u003c/p\u003e\n \u003cp\u003eMultivariable logistic regression was performed with mobility restrictions as the exposure of interest and APCO as the outcome of interest, adjusted for the potentially confounding effects of the covariables selected from the DAG. Cases with missing values from these variables were not included in the multivariable regression.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe H-TR identified 460 patients with major trauma undergoing thoracolumbar spinal arthrodesis. Six cases were excluded: Three did not undergo thoracolumbar spinal arthrodesis; one patient underwent delayed repair in a subsequent admission and two patients were missing clinical notes. Of the subsequent 454, A total of 34 cases of ACPO were identified (7.5%). Dilated colon was seen on imaging in two patients but not considered as ACPO, due to diagnoses of clostridium difficile colitis and mechanical obstruction respectively. Post-operative mobility status was not documented in three patients.\u003c/p\u003e \u003cp\u003eNo mortality from ACPO was seen. No patients required surgery, and two patients underwent colonoscopic decompression. The remainder were successfully treated medically, including enema and rectal tube utilisation. Neostigmine was not used. Full details on treatment have been reported elsewhere [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDemographics and baseline comparisons are reported in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Age, gender, ASA score and comorbidity status were similar across the two groups. However, patients with mobility restrictions prescribed tended to have higher ISS and higher rates of associated injuries, including chest wall, abdominal and other fractures. Spinal fracture distribution and surgical management were broadly similar. In addition, length of stay was substantially longer in patients with prescribed mobility restrictions (median 19 days versus 9 days).\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\u003eDemographics\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\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo mobility Restrictions\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMobility restrictions\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNumber\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e375\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian Age (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45 (27\u0026ndash;61)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 (30\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemale gender\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e98 (26.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (23.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian ASA (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (0\u0026ndash;1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (0\u0026ndash;1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNo Comorbidities\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37.6% (158)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.2% (14)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian ISS (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (10\u0026ndash;21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.5 (18\u0026ndash;38)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eInjuries\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpinal cord injury\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40 (10.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (17.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMajor chest wall injury\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e127 (33.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44 (57.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSolid organ abdominal injury\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32 (8.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18 (23.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrauma laparotomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24 (6.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (9.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e206 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 (32.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-spinal orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e111 (29.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73 (96.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eThoracic fracture\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e225 (60.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49 (65.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian number of fractures (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 (1\u0026ndash;2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (1\u0026ndash;2)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian levels of fusion (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (4\u0026ndash;6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (4\u0026ndash;6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePosterior spinal approach\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e327 (87.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67 (88.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian duration of surgery (min; IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e107 (83\u0026ndash;135)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e121 (92\u0026ndash;164)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePCA use\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e303 (80.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61 (80.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian hospital length of stay (Days, IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (6\u0026ndash;14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (11\u0026ndash;27)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eACPO occurrence (N,%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (15.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eUnivariable regression\u003c/h2\u003e \u003cp\u003eThe findings of univariable regression are reported in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Post-operative mobility restrictions were associated with an OR of 3.0 (95% CI 1.4\u0026ndash;6.0, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) for the development of ACPO.\u003c/p\u003e \u003cp\u003eThere was no evidence of an association between ACPO development and age, ISS score, fracture level, surgical approach or gender. PCA use had a strong correlation with ACPO development, however this was limited by very low numbers. A single patient developed ACPO in the absence of PCA use, making this data difficult to interpret.\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\u003eUnivariable logistic regression for development of ACPO\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=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOdds ratio for ACPO (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN without ACPO\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eN with ACPO\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNumber\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e420\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemale gender\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.7 (0.3\u0026ndash;1.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e109 (29%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (20.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eASA Score\u003c/b\u003e\u003c/p\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003cp\u003e4.5 (1\u0026ndash;20)\u003c/p\u003e \u003cp\u003e2.4 (0.5\u0026ndash;11.6)\u003c/p\u003e \u003cp\u003e2.3 (0.4\u0026ndash;14.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003cp\u003e0.30\u003c/p\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65 (19.1%)\u003c/p\u003e \u003cp\u003e130 (38.1%)\u003c/p\u003e \u003cp\u003e97 (28.4%)\u003c/p\u003e \u003cp\u003e42 (12.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (6.7%)\u003c/p\u003e \u003cp\u003e18 (60%)\u003c/p\u003e \u003cp\u003e7 (23.3%)\u003c/p\u003e \u003cp\u003e3 (10%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLevel of fracture\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThoracic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e258 (61.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17 (50%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.6 (0.8\u0026ndash;3.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e160 (38.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17 (50%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSurgical approach\u003c/b\u003e\u003c/p\u003e \u003cp\u003eAnterior or circumferential\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53 (12.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePosterior approach\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.1 (0.4\u0026ndash;3.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e366 (87.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30 (88.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eISS Categories\u003c/b\u003e\u003c/p\u003e \u003cp\u003eISS\u0026thinsp;\u0026lt;\u0026thinsp;12\u003c/p\u003e \u003cp\u003eISS 13\u0026ndash;23\u003c/p\u003e \u003cp\u003eISS\u0026thinsp;\u0026gt;\u0026thinsp;25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003cp\u003e1.9 (0.7\u0026ndash;5.3)\u003c/p\u003e \u003cp\u003e1.9 (0.6\u0026ndash;5.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e104 (24.8%)\u003c/p\u003e \u003cp\u003e226 (53.8%)\u003c/p\u003e \u003cp\u003e90 (21.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5 (14.7%)\u003c/p\u003e \u003cp\u003e21 (76.5%)\u003c/p\u003e \u003cp\u003e8 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.8 (0.9\u0026ndash;3.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e200 (47.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21 (61.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpinal cord injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.6 (1.1 -6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45 (10.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-spinal orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.7 (0.8\u0026ndash;3.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e169 (40.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18 (52.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePost-operative mobility restrictions\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.0 (1.4\u0026ndash;6.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e64 (15.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12 (35.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePCA use (vs non-use)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.45 (1.1\u0026ndash;62.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e332 (79.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e33 (97.1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eMultivariable regression\u003c/h2\u003e \u003cp\u003eMultivariable analysis was performed using logistic regression, controlling for potential confounders as identified in the DAG. ASA score was initially planned for inclusion in the model, though was poorly recorded, such that 80 missing values were identified. To avoid excessive reduction in sample size, this was excluded from the model. After adjusting for the effects of age, gender, injury severity score and injury patterns, PCA use and spinal cord injury, post-operative mobility restrictions retained evidence of an association with ACPO (OR 3.0, 95% CI: 1.1\u0026ndash;8.2, P\u0026thinsp;=\u0026thinsp;0.03).\u003c/p\u003e \u003cp\u003ePCA use was noted as a significant contributor to ACPO development in this model, however as noted previously, the low numbers produced very wide confidence intervals that were not reliable. A sensitivity analysis was performed excluding PCA use. There was no major change to the effect of mobility restrictions (OR 3.2, 95% CI: 1.2\u0026ndash;8.6, P\u0026thinsp;=\u0026thinsp;0.02). A second sensitivity analysis was performed including ASA score, with only minimal change to the effect of mobility restrictions (OR 3.2, 95% CI 1.0\u0026ndash;9.9, P\u0026thinsp;=\u0026thinsp;0.04, N\u0026thinsp;=\u0026thinsp;361).\u003c/p\u003e \u003cp\u003eSpinal cord injury had some evidence of association with ACPO development on univariable logistic regression (OR 2.5, 95% CI: 1.1\u0026ndash;6.0, P\u0026thinsp;=\u0026thinsp;0.03), however had less evidence of association on multivariable logistic regression analysis (OR 2.5, 95% CI: 1.0\u0026ndash;6.5, P\u0026thinsp;=\u0026thinsp;0.06).\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\u003eMultivariable logistic regression for effect of mobility restrictions on ACPO development, after adjusting for gender, age, ISS, other injuries and PCA usage\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=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\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\u003eOR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\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\u003e\u003cb\u003ePost-operative mobility restriction\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.0 (1.1\u0026ndash;8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFemale Gender\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.8 (0.3\u0026ndash;1.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge Categories\u003c/b\u003e\u003c/p\u003e \u003cp\u003e18\u0026ndash; 34 years\u003c/p\u003e \u003cp\u003e35\u0026ndash;54 years\u003c/p\u003e \u003cp\u003e55 years +\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003cp\u003e1.3 (0.6\u0026ndash;3.1)\u003c/p\u003e \u003cp\u003e0.8 (0.3\u0026ndash;2.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.53\u003c/p\u003e \u003cp\u003e0.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eISS Categories\u003c/b\u003e\u003c/p\u003e \u003cp\u003eISS\u0026thinsp;\u0026lt;\u0026thinsp;12\u003c/p\u003e \u003cp\u003eISS 13\u0026ndash;25\u003c/p\u003e \u003cp\u003eISS\u0026thinsp;\u0026gt;\u0026thinsp;25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003cp\u003e1.2 (0.4\u0026ndash;3.6)\u003c/p\u003e \u003cp\u003e0.7 (0.1\u0026ndash;3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.8 (0.8\u0026ndash;4.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpinal cord injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.5 (0.97\u0026ndash;6.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMajor non-spinal orthopaedic injury\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e.01 (0.4\u0026ndash;2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePCA use\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8.4 (1.1\u0026ndash;64.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\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\u003e \u003cb\u003eN\u0026thinsp;=\u0026thinsp;450. Pseudo R\u003c/b\u003e \u003csup\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sup\u003e\u0026thinsp;\u003cb\u003e=\u0026thinsp;0.07.\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eACPO in this population of major trauma patients undergoing urgent spinal fixation was a relatively common but low-morbidity complication. No mortality was seen from ACPO, and no patient required surgery. This was less severe than expected, but not dissimilar to other contemporaneous studies [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this study, reduced mobility, represented by mobility restrictions prescribed by surgeons at the time of spinal surgery, was associated with an approximately three-fold increased risk of ACPO. To our knowledge, this is the first report of a relationship between reduced mobility and ACPO after adjusting for potentially confounding variables. This provides further support to the hypothesis that impaired mobility contributes to ACPO development. However, the pathophysiologic mechanisms behind this are unknown. Immobility has certainly been linked to constipation [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], though even there the mechanism is not yet understood. There remains considerable room for research to understand the pathophysiology underlying ACPO.\u003c/p\u003e \u003cp\u003eThe chief limitation to this study relates to defining and recording reduced mobility. We used a proxy measurement of prescribed, post-operative mobility restrictions to provide a standardised measure. However, this does not consider gradations in degree of mobility, and nor does it necessarily reflect actual mobility observed. Non-compliance with mobility recommendations (whether encouraging or limiting activity) reduces the clinical accuracy of this proxy measure. Other studies that have reported on post-operative mobility have also described poor mobility in vague terms, such as slow progression relative to a standard physiotherapy reference [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], or \u0026lsquo;delay to mobilisation\u0026rsquo; [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Improved precision in the measurement of mobility would likely require a prospective study with dedicated assessment of mobility each day.\u003c/p\u003e \u003cp\u003eIn addition, whilst all attempts were made to identify and reduce confounding via DAG and multivariable logistic regression, residual bias remains a potential weakness in this retrospective cohort. One potential residual confounder is opiate exposure. Numerous studies have linked opiate exposure, including PCA use, with ACPO development [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], [\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u0026ndash;[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In this study, opiate exposure could only be recorded via the mode of delivery, such as PCA use. Here, the single event that occurred without a PCA makes interpreting data difficult and resulted in very broad confidence intervals. Direct measurement of opiate intake via a prospective study design would enable more accurate comparison. Nonetheless, minimising opiate exposure has extensive advantages and should be promoted.\u003c/p\u003e \u003cp\u003eSpinal cord injury is a second potential variable confounding the relationship between ACPO and mobility restrictions. The literature has not previously reported a direct link between spinal cord injury and ACPO development, though changes to colonic function (including constipation and incontinence) are documented [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Mechanistically, spinal cord injury could plausibly contribute to ACPO development either via disruption of autonomic reflex pathways or via the associated immobility that may occur as a result [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. There was little evidence of effect on multivariable regression analysis. However, this study lacked power for this factor, and a larger sample size may be required for precision.\u003c/p\u003e \u003cp\u003eIdeally, a prospective study would be performed to evaluate all of these risk factors, with attention to accurate recording of actual mobility, forms and dosages of opiates and other analgesia used. This would generate a more accurate assessment of contributing aetiology. In the meantime, strategies to reduce these risk factors are in line with best practice and should be pursued.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eACPO was a relatively common but low-morbidity complication of emergent surgical fixation of the thoracic or lumbar spine following trauma, occurring in 7.5%.\u003c/p\u003e \u003cp\u003eSurgeon-prescribed mobility restrictions were associated with a threefold increase in ACPO development in multivariable analysis, controlling for age, gender, injury severity score, PCA use, injury pattern and spinal cord injury.\u003c/p\u003e \u003cp\u003eConsideration to minimisation of mobility restrictions and earlier post-operative mobilisation, where feasible, may help reduce rates of ACPO development. Minimisation of intravenous opiate use may also be beneficial. Further research should focus on these areas, ideally through prospective methods, to further evaluate individual risk contribution with the goal of preventing ACPO.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of Interest Disclosure\u003c/strong\u003e: There is no conflict of interest to report\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Disclosure:\u003c/strong\u003e No funding was received for this research.\u003c/p\u003e\n\u003cp\u003eAcknowledgments: Kellie Gumm, Laura Bennett, Cheng Feng, Dilshan Udayasiri\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The authors have no competing interests, either financial or non-financial, to disclose.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eC. I. Wells, G. O. Grady, I. P. Bissett, C. I. Wells, G. O. Grady, and I. P. Bissett, \u0026ldquo;Acute colonic pseudo-obstruction : A systematic review of aetiology and mechanisms,\u0026rdquo; \u003cem\u003eWorld J. 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Med.\u003c/em\u003e, vol. 12, no. 7, p. 1141, Jul. 2022, doi: 10.3390/jpm12071141.\u003c/li\u003e\n\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":"Acute colonic pseudo-obstruction, Ogilvie Syndrome, Spinal Fracture, Neostigmine, mobility","lastPublishedDoi":"10.21203/rs.3.rs-3874636/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3874636/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eAcute colonic pseudo-obstruction (ACPO) is a common and potentially serious complication of surgical and trauma care. A possible contributor to ACPO development is impaired mobility. Major trauma patients, particularly those with spinal trauma, are at risk of prolonged mobility restrictions. The aim of this study was to assess the association between impaired mobility and the development of ACPO in major trauma patients undergoing acute thoraco-lumbar spinal fixation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA retrospective cohort study involving major trauma patients admitted to a tertiary trauma facility was performed. The Hospital Trauma Registry was utilised to identify consecutive major trauma patients having urgent thoraco-lumbar spinal fixation. ACPO was defined as dilation of the transverse colon\u0026thinsp;\u0026gt;\u0026thinsp;6cm or caecum\u0026thinsp;\u0026gt;\u0026thinsp;9cm without mechanical cause. Immobility was defined by proxy as surgeon-prescribed mobility restrictions. Analysis was performed using multivariable logistic regression.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eACPO occurred in 34 of 454 patients studied (7.5%). Colonoscopic decompression was required twice. Neostigmine and surgical resection were not required. There was no ACPO-related mortality. On multivariable regression, adjusted for confounding variables, post-operative mobility restrictions were associated with a three-fold increase in odds of ACPO (Odds Ratio 3.0; 95% confidence interval 1.1\u0026ndash;8.2, P\u0026thinsp;=\u0026thinsp;0.03).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eACPO was a common, although low-morbidity complication in this cohort. Surgically-prescribed mobility restrictions were associated with higher odds of ACPO in major trauma patients having thoraco-lumbar spinal fixation. Attention should be given to early mobilisation, where possible, in these patients.\u003c/p\u003e","manuscriptTitle":"Association between post-operative mobility restrictions and acute colonic pseudo-obstruction after spinal fixation in major trauma patients: a retrospective cohort study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-19 12:17:52","doi":"10.21203/rs.3.rs-3874636/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":"936016f1-1ca0-42fa-a1fc-20af69e96aef","owner":[],"postedDate":"January 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-10-04T21:23:24+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-19 12:17:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3874636","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3874636","identity":"rs-3874636","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}