Impact of Door-Opening Side Selection on Surgical Outcomes in single-door cervical laminoplasty for Asymmetric Ossification of the Posterior Longitudinal Ligament

Impact of Door-Opening Side Selection on Surgical Outcomes in single-door cervical laminoplasty for Asymmetric Ossification of the Posterior Longitudinal Ligament | 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 Impact of Door-Opening Side Selection on Surgical Outcomes in single-door cervical laminoplasty for Asymmetric Ossification of the Posterior Longitudinal Ligament Mingyue Fan, Yongjun Hu, Jinxi An, Sen Wang, Dong Chen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7663372/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 This study investigates the impact of the choice of door-opening side on neurological recovery, radiographic decompression adequacy, and complications in patients with asymmetric ossification of the posterior longitudinal ligament (OPLL), so as to provide evidence-based guidance for the selection of surgical side . Methods A retrospective analysis was performed on the data of 35 patients with asymmetric C-OPLL who underwent cervical posterior single-door laminoplasty (CPSDL) from September 2020 to January 2024. Patients were divided into two groups: the ipsilateral group, when the door-opening side was consistent with the predominant OPLL occupation side, and the contralateral group, when the door-opening side was inconsistent with the predominant OPLL occupation. The following parameters were evaluated: Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) for pain, C2–7 Cobb angle, sagittal diameter of the cervical canal, C2–7 sagittal vertical axis (SVA), axial length and thickness of ossified lesions. Clinical outcomes were compared between the two groups to comprehensively evaluate the impact of the choice of door-opening sidein asymmetric OPLL. Results There were no significant differences between the two groups in postoperative Neck Disability Index (NDI) score, C2-7 SVA, incidence of C5 nerve root palsy, and axial symptoms, and total incidence of complications. The ipsilateral group had more significant improvements in C2-7 Cobb angle, sagittal diameter of cervical spinal canal, VAS, and JOA score. Conclusion For patients with asymmetric C-OPLL, the predominant OPLL occupation side is preferred as the door-opening side in CPSDL C-OPLL Posterior open-door laminoplasty C2-C7 Cobb angle C2-7 SVA Figures Figure 1 Figure 2 Figure 3 Introduction Cervical ossification of posterior longitudinal ligament (C-OPLL) is a multifactorial disease characterized by progressive heterotopic ossification and calcification of the posterior longitudinal ligament. It can lead to cervical spinal canal stenosis, as well as compression of the spinal cord and nerve roots. The symptoms include neck pain, limited mobility, limb numbness, and motor dysfunction, and severe cases often require surgical treatment [ 1 ].Since the 20th century, with the widespread application of electronic devices and the rise of short-video platforms in recent years, behavioral patterns such as maintaining a head-down posture for a long time when using mobile devices and working at desks have contributed to a significant younger trend in the onset of cervical spondylosis. In this context, C-OPLL has become an important pathogenic factor of cervical spondylosis. Clinical studies have shown that patients with symptoms lasting more than 23 months tend to have a poor postoperative prognosis and require timely surgical intervention [ 2 ]. Orthopedic surgeons usually choose the side with the most obvious symptoms and signs to treat C-OPLL patients. However, in asymmetric C-OPLL cases where the more symptomatic side contralateral to the predominant OPLL occupation, no consensus exists regarding optimal laminoplasty side selection. In this study, we retrospectively analyzed imaging data (CT, MRI, and radiographs) and surgical outcomes from 35 patients with multilevel asymmetric C-OPLL undergoing laminoplasty with different opening approaches, to determine the optimal decompression side for open-door laminoplasty in multilevel asymmetric C-OPLL. However, for asymmetric C-OPLL, when the side with more severe symptoms and signs is on the opposite side of the side with a larger ossification-occupied area, there is currently no research to determine which side should be the opening side. Based on this, in this study, we attempted to determine the optimal opening side for single-door laminoplasty in the treatment of multi-segment asymmetric C-OPLL by retrospectively analyzing the CT, MRI and X-ray data of 35 patients with multi-segment asymmetric C-OPLL and the surgical results of each opening side. Materials and Methods Patients This retrospective study enrolled 35 consecutive C-OPLL patients who met the inclusion criteria between September 2020 and January 2024, all with complete clinical documentation and follow-up data. Inclusion criteria were: (1) Patients with sC-OPLL who meet the surgical criteria; (2) Patients whose ossified lesions involve 3 or more spinal segments and are K-line positive; (3) Patients with asymmetric C-OPLL confirmed by radiographic examination; (4) Patients in whom the side with more severe symptoms and signs is contralateral to the side with a larger occupied area by ossification; (5) Patients who only underwent posterior cervical single-door laminoplasty; (6) Patients with a postoperative follow-up duration of more than 1 year and complete data. Exclusion Criteria were: (1) Patients who do not meet the above inclusion criteria; (2) Patients with similar symptoms and signs on both sides; (3) Patients with similar occupied areas by ossification on both sides; (4) Patients with a history of infection, malignant tumor, or severe trauma; (5) Patients with neurological diseases (including fractures, dislocations, syringomyelia, poliomyelitis, spinal cord tumors, Parkinson's disease, ankylosing spondylitis, cervical spine infection, etc.) or a history of cervical spine surgery; (6) Patients with a history of substance abuse; (7) Patients who refuse to participate in follow-up. Clinical and Radiologic Assessment The study was conducted through a retrospective review of all patients. The study cohort consisted of 22 male and 13 female patients,with an age range of42-75 years (mean age: 59.91 years). Patients were assigned to the ipsilateral group when the door-opening side was consistent with the side of the larger ossification-occupied area; when the door-opening side was inconsistent with the side of the larger ossification-occupied area, patients were assigned to the contralateral group. The ipsilateral group (n = 20) included 13 male patients and 7 female patients, with an age range of 42–75 years (mean age: 60.20 ± 9.47 years), a disease duration of 7–45 months (mean duration: 39.91 ± 1.47 months), 4 cases complicated with hypertension, and 3 cases complicated with diabetes mellitus. •The Contralateral Group (n = 15) was composed of 9 male patients and 6 female patients, with an age range of 48–68 years (mean age: 59.53 ± 6.64 years), a disease duration of 9–50 months (mean duration: 42.28 ± 2.23 months), 3 cases complicated with hypertension, and 2 cases complicated with diabetes mellitus. Statistical analysis of baseline data showed that there were no statistically significant differences between the two groups in parameters such as age, gender distribution, body mass index (BMI), and composition of underlying diseases (P > 0.05), indicating good comparability between the groups. This study was reviewed and approved by the Ethics Committee of our hospital (Approval No.: 2025-KY-Y016-001). All asymmetric C-OPLL patients underwent comprehensive cervical spine imaging including radiographs, Three-dimensional computed tomography (3D-CT) and Magnetic resonance imaging (MRI). Based on imaging characteristics, OPLL lesions were classified into four subtypes[ 3 ]: 1. Continuous type (bridging ossification across multiple vertebral levels) 2. Segmental type (non-contiguous ossifications at posterior vertebral margins with preserved ligament integrity between segments) 3. Focal type (localized ossification within a single vertebral level) 4. Mixed type (exhibiting both continuous and segmental characteristics). Figure 1To determine the optimal surgical approach, a comprehensive evaluation was conducted, incorporating ossification type, the severity of spinal canal stenosis, the site of spinal cord compression, and clinical symptoms. All patients underwent posterior cervical open-door laminoplasty, followed by postoperative radiographic assessment. Clinical assessment Gender, age, and body mass index (BMI) were recorded as baseline characteristics. Intraoperative blood loss (milliliters, mL) and surgical duration (minutes) were all included in the baseline data. Axial pain was quantitatively evaluated using the Visual Analog Scale (VAS); Spinal nerve function was assessed via the Japanese Orthopaedic Association The Neck Disability Index (NDI) was used to evaluate the impact of cervical spine problems on daily life. Data on VAS, JOA, and NDI scores were all collected preoperatively and at the 1-year postoperative follow-up. Cervical spine imaging parameters (including spinal canal sagittal diameter, C2-7 Cobb angle, C2-7sagittal vertical axis (SVA), ossification length and thickness, and spinal cord shift) were also collected preoperatively and at the 1-year postoperative follow-up. Radiographic measurement parameters were defined as follows: The C2-7 Cobb angle (the acute angle formed by the intersection of lines perpendicular to the inferior endplates of C2 and C7 on lateral radiographs) Ossification length and thickness were measured as follows: For axial length measurement, on CT bone window sagittal images, a line segment was drawn from the cephalad to caudal ends of the ossification. For discontinuous or irregular ossifications, multiple segments were measured along the longest diameter of each ossified segment, with the total length calculated as the sum of all segments. The thickness measurement protocol was as follows: At point a (the intersection of the spinal canal and the thickest portion of ossification), a line parallel to the posterior vertebral border was drawn. From point a, a perpendicular line to the posterior vertebral border was constructed, intersecting the border or its extension at point b. The distance between points a and b was defined as the ossification thickness. The sagittal diameter of the spinal canal was measured on axial CT images as the shortest distance from the midpoint of the posterior vertebral border to the corresponding posterior spinal canal wall, with the final value representing the average across all measured segments. The C2-7 sagittal vertical axis (SVA) was determined on lateral cervical radiographs by measuring the vertical distance between a plumb line dropped from the midpoint of the C2 vertebral body and the posterosuperior corner of C7. The SVA increase was calculated as the postoperative SVA minus preoperative SVA, with greater increases indicating worse sagittal alignment of the cervical spine. The definitions of radiological measurement parameters are as follows: 1. C2-7 Cobb angle: On lateral radiographs, two lines perpendicular to the inferior endplates of the C2 and C7 vertebrae are drawn respectively; the acute angle formed by the intersection of these two lines is defined as the C2-7 Cobb angle. 2. Measurement methods for ossification length and thickness: Length measurement: On sagittal images of CT bone windows, a line segment is drawn from the cephalad to the caudal end of the ossification, and the length is measured directly. For discontinuous or irregular ossifications, measurements are taken along the longest diameter of each ossified segment separately, and the total length is calculated as the sum of all segments. Thickness measurement: First, identify Point A (the intersection of the spinal canal and the thickest part of the ossification), and draw a line parallel to the posterior vertebral border through Point A. Then, draw a line perpendicular to the posterior vertebral border from Point A, which intersects the posterior vertebral border or its extension at Point B. The distance between Points A and B is defined as the ossification thickness. 3. Spinal canal sagittal diameter: On axial CT images, measure the shortest distance from the midpoint of the posterior vertebral border to the corresponding posterior wall of the spinal canal; the final result is the average value of all measured segments. 4. C2-7 sagittal vertical axis (SVA): On lateral cervical radiographs, a plumb line is drawn downward from the midpoint of the C2 vertebral body; the vertical distance between this plumb line and the posterosuperior corner of the C7 vertebral body is defined as the C2-7 SVA. 5. SVA increase value: Calculated using the formula "Postoperative SVA value - Preoperative SVA value". A larger increase indicates worse sagittal alignment of the cervical spine. Surgical technique Prior to surgery, the patient underwent skin preparation of the head and neck surgical area. After general anesthesia induction, the patient was placed in a prone position, with the forehead and face fixed using a silicone ring, and the neck maintained in a moderate forward flexion position. Soft protective pads were applied to the anterior chest wall, bilateral anterior superior iliac spines, and knee joint areas. Following routine disinfection and draping of the surgical field, a single-door laminoplasty was performed (taking the C3-C6 segments as an example). A midline posterior cervical incision was made, extending from the external occipital protuberance to the C7 spinous process. The skin, subcutaneous tissue, and ligamentum nuchae were divided in layers. After retractor placement, subperiosteal dissection was performed to expose the C3–C6 laminae, spinous processes, and lateral mass joints. A high-speed burr was used to grind away the outer cortex of the C3-C6 laminae on one side, while preserving the inner cortex to form a 0.3 cm-wide bone groove (serving as the "hinge" for the single-door procedure).. An ultrasonic bone scalpel was then used to make a full-thickness incision on the other side of the C3-C6 laminae. The entire length of the C3-C6 laminae was lifted toward one side, maintaining an 8 mm gap between the broken ends of the laminae on the opposite side. Intraoperatively, after confirming satisfactory door-opening and adequate spinal canal decompression, internal fixation titanium plates were placed between the fractured ends of the C3, C4, C5, and C6 laminae (post-door-opening) to maintain the lifted position and stability of the C3-C6 laminae. After irrigation and hemostasis, autograft bone harvested from the spinous processes and laminar grooves was morselized into 2–3 mm particles and packed into the hinge site to promote bony fusion. A drainage tube was placed, and layered closure of deep fascia, superficial fascia, subcutaneous tissue, and skin was performed. The incision was covered with sterile dressing. All procedures were performed by the same senior spine surgeon. Postoperative Management After surgery, patients were routinely administered antibiotics for 48 hours to prevent infection, supplemented with neurotrophic agents, glucocorticoids, non-steroidal anti-inflammatory drugs (NSAIDs), and dehydrating agents for 3–6 days. For patients with cerebrospinal fluid (CSF) leakage, the drainage device was retained for 7–9 days and removed when the 24-hour drainage volume was less than 30 mL. Starting from the 2nd postoperative day, patients were instructed to gradually ambulate under the protection of a cervical collar and with the supervision of family members. After 4 weeks of cervical collar fixation, patients were guided to perform cervical spine flexion and extension functional exercises. Before discharge, patients were advised to return to the hospital regularly for reexaminations of imaging findings and functional assessments. Statistical analysis SPSS 26.0 statistical software was used for data analysis. The Shapiro-Wilk normality test was conducted on continuous variables such as JOA scores, VAS scores, and cervical curvature. Data that conformed to a normal distribution were expressed as mean ± standard deviation (x̄ ± s). For indicators related to ossification, the independent samples t-test was applied when the assumptions of normal distribution and homogeneity of variance were satisfied; if the variance was heterogeneous, the Wilcoxon rank-sum test was used instead. For categorical variables including axial symptoms, CSF leakage, and C5 nerve root palsy, the data were described in the form of frequency (percentage) and analyzed using the chi-square test. A P-value < 0.05 was considered to indicate a statistically significant difference. Results Demographics Analysis of baseline data revealed no statistically significant differences between the two groups of patients in parameters including age, gender distribution, and BMI (P > 0.05) (Table 1 ). Clinical outcomes At 1-year follow-up, the VAS scores of patients in both groups were significantly lower than those before surgery, with statistically significant differences (P 0.05). The JOA scores of patients in both groups were significantly higher at 1 year postoperatively than preoperatively (P 0.05); ② At 1-year postoperative follow-up, the JOA score of the ipsilateral group was significantly higher than that of the contralateral group (P < 0.05), suggesting that the ipsilateral group had a superior clinical outcome in terms of neurological function recovery; Additionally, there were no statistically significant differences in NDI scores between the two groups either before surgery or at 12 months 1-year follow-up (both P > 0.05) (Table 2). Radiological Results As shown in Table 3, all C2-C7 Cobb angle, spinal canal sagittal diameter, and C2-C7 SVA measurements passed normality (Shapiro-Wilk) and homogeneity of variance (Levene's) tests, permitting independent samples t-tests for intergroup comparisons. The results showed that:1) Both groups showed significant reduction in C2-C7 Cobb angle at 1-year follow-up compared with baseline values (both p < 0.05) .2) The contralateral group exhibited greater Cobb angle loss than the ipsilateral group (p < 0.05), indicating more deterioration of sagittal alignment stability. 3) Both groups achieved significant increases in spinal canal sagittal diameter (both p < 0.001). 4) The ipsilateral group demonstrated greater diameter expansion than the contralateral group (p < 0.05), suggesting superior anatomical restoration of canal volume. 5) Both groups showed significant C2-C7 SVA increases at 1-year follow-up (both p 0.05), suggesting equivalent impact on sagittal balance regardless of surgical approach side (Table 3). At 1-year follow-up, the axial length and thickness of the ossification increased significantly in patients of both groups. Among them, the changes in axial length and thickness of the ossification in the contralateral group were greater than those in the ipsilateral group, with statistically significant differences (P < 0.05) (Table 4 ). As classified in Fig. 2 using established radiographic criteria, ossification of the posterior longitudinal ligament (OPLL) was categorized into four subtypes: Baseline subtype distribution: Consistent group: Segmental (n = 2), Focal (n = 3), Mixed (n = 5), Continuous (n = 10). Contralateral group: Segmental (n = 2), Focal (n = 2), Mixed (n = 4), Continuous (n = 7). At 1-year follow-up, both groups showed: Significant dimensional changes in thickness/axial length (both p < 0.05). This suggests surgical approach selection (consistent vs contralateral) does not significantly influence OPLL subtype progression. Radiological follow-up data revealed the distribution of preoperative ossification types in the ipsilateral group: 2 cases of segmental type, 3 cases of focal type, 5 cases of mixed type, and 10 cases of continuous type. For the contralateral group, the preoperative ossification type distribution was as follows: 2 cases of segmental type, 2 cases of focal type, 4 cases of mixed type, and 7 cases of continuous type.​ At the 1-year postoperative evaluation, the ossification foci in both groups exhibited changes in thickness and axial length, with no significant evolution in ossification types observed (P > 0.05). This finding suggests that the selection of the door-opening side bears no direct correlation to the transformation of ossification types (Fig. 2 ). Complications None of the 35 patients developed intraspinal hematoma, spinal cord injury, CSF leakage, postoperative laminoplasty closure, or postoperative kyphosis. In the ipsilateral group: there were 4 cases of postoperative axial symptoms (20%), 2 cases of C5 nerve root palsy (10%), and 9 cases of transient pain in the deltoid region (45%), with an overall complication rate of 25%.​ In the contralateral group: there were 2 cases of postoperative axial symptoms (13.33%), 1 case of C5 nerve root palsy (6.67%), and 3 cases of transient pain in the deltoid region (20%), with an overall complication rate of 13.33%.​ No significant differences were observed between the two groups in the incidences of C5 nerve root palsy, transient pain in the deltoid region, axial symptoms, or the overall complication rate (P > 0.05) (Table 5 ). Typical cases The patient is a 69-year-old male. He has experienced numbness and weakness in his left upper limb for 4 years, and the symptoms have worsened, accompanied by weakness in both lower limbs and unsteady walking for 6 months. After admission, comprehensive examinations were conducted to rule out surgical contraindications. Under general anesthesia, a posterior cervical single-door laminoplasty was performed to expand the spinal canal. Postoperative re-examination showed that the volume of the spinal canal was significantly expanded, the spinal cord was decompressed adequately, and the neurological function improved significantly compared to before the operation(Fig. 3 ). Discussion C-OPLL is a chronic progressive disorder characterized by heterotopic ossification of the cervical posterior longitudinal ligament, which often leads to spinal cord compression and neurological dysfunction. Posterior decompression surgery is currently the preferred treatment for most patients with long-segment C-OPLL in clinical practice[ 4 ]. Posterior cervical surgical approaches include laminoplasty (LAMP), laminectomy (LAME), and the emerging posterior hybrid technique. Among these, LAMP remains the most widely used surgical method for C-OPLL [ 5 ]. Among the derived techniques of LAMP, the single-door laminoplasty has the widest clinical application[ 6 ]. This technique expands the spinal canal volume by unilaterally lifting the laminae at multiple segments, utilizing cervical lordosis and the "bowstring effect" to facilitate posterior spinal cord migration, thereby avoiding compression from the anterior ossification [ 7 ]. It is widely recognized as a reliable surgical technique. The measurement of the occupied area by ossification of the posterior longitudinal ligament was one of the key measurement techniques in this study. However, unavoidable errors still exist, which can be attributed to the following factors. First, the "partial volume effect" of MRI may affect the accuracy of identifying the segments responsible for cervical spinal cord compression. Second, due to differences in imaging principles, the localization of relevant segments on MRI may not be completely consistent with that on the corresponding CT scans. Third, inherent errors exist in determining the mid-sagittal line of the spinal canal on axial CT images. Fourth, for the measurement of the left or right half of the ossified structure, we used image system recognition combined with manual auxiliary calculation to determine the occupied area; nevertheless, unavoidable measurement errors remain. To reduce measurement errors, two investigators independently conducted multiple measurements, and the results were averaged. In the present study, the postoperative JOA scores increased in both groups, which is consistent with the findings of Hou Y et al [ 8 ], indicating that single-door laminoplasty can effectively relieve spinal cord compression and improve neurological function. Notably, the improvement in JOA scores was more significant in the ipsilateral group than in the contralateral group, suggesting that selecting a door-opening side consistent with the side of the ossification-occupied area may be more conducive to neurological function recovery. Previous studies have identified K-line positivity, door-opening angle, and door-opening width as key determinants of JOA score improvement [ 9 ]. At 12-month follow-up, the ipsilateral group demonstrated significantly greater increases in cervical spinal canal sagittal diameter compared to the contralateral group. Therefore, we speculate that the higher JOA scores in the ipsilateral group may be related to the more thorough decompression effect achieved during surgery. This is because when the door-opening side is consistent with the side of the ossification-occupied area, the surgery can more directly relieve the ventral compression of the spinal cord, resulting in more obvious posterior migration of the spinal cord, better spinal cord expansion, and more complete recovery of the spinal cord morphology—thereby improving neurological function more effectively. These findings are consistent with the research results of Basu S [ 10 ] and Sodeyama T [ 11 ] et al. Previously, evaluation of surgical efficacy for C-OPLL was limited to the degree of improvement in symptoms and neurological function, the incidence of postoperative complications, and changes in parameters such as cervical curvature and range of motion. With the deepening understanding of C-OPLL, the progression of ossification has been recognized as an important indicator for evaluating the long-term surgical efficacy and has gradually become a research focus among scholars [ 12 ]. Previous studies have observed that laminoplasty accelerates the progression of ossification in C-OPLL patients. Kang et al. [ 13 ] followed 50 C-OPLL patients for 37.6 ± 16.8 months and found that the ossification increased by an average of 1.53 ± 1.04 mm. A study by Wang et al. [ 14 ] revealed that the incidence of postoperative ossification progression increased from 3.3% to 74.5%. In the present study, the axial length and thickness of ossification increased in all patients at 1-year follow-up, indicating that the ossification process of C-OPLL may continue to progress postoperatively. Specifically, the changes in axial length and thickness of ossification were 2.24 ± 0.33 mm and 1.56 ± 0.08 mm in the contralateral group, respectively, while those in the ipsilateral group were 1.85 ± 0.32 mm and 1.49 ± 0.13 mm, respectively. The difference between the two groups was statistically significant (P < 0.05), suggesting that selecting a door-opening side inconsistent with the side of the ossification-occupied area may accelerate the progression of ossification. The precise mechanism underlying C-OPLL progression has not been fully clarified. A study by Lee et al. [ 15 ] suggested that it may be related to the following factors:​ (1) Biomechanical changes: After surgical decompression, the local stress distribution of the cervical spine changes, which may stimulate the further growth of ossification; (2) Inflammatory response: Surgical trauma may trigger a local inflammatory response, releasing various cytokines that promote osteoblast differentiation and bone matrix deposition; (3) Genetic factors: The pathogenesis of C-OPLL is closely related to genetic factors, and certain gene polymorphisms may affect the progression rate of ossification. Based on radiological manifestations, ossification of OPLL is categorized into four types: focal, segmental, continuous, and mixed [ 16 ]. In the present study, the distribution of ossification types was similar between the ipsilateral group and the contralateral group before surgery and at 1 year postoperatively. However, increases in the axial length and thickness of the ossification suggest that—despite unchanged types—the volume and scope of the ossification may still be expanding. This finding aligns with previous studies, confirming that the ossification process in C-OPLL is dynamic and progressive. Surgical intervention may influence ossification progression by modifying the local biomechanical environment and relieving spinal cord compression. In this study, ossification progressed more slowly in the ipsilateral group than in the contralateral group, potentially due to the following factors: (1) More thorough decompression: When the door-opening side aligns with the ossification-occupied area, surgery directly relieves spinal cord compression and reduces local stress concentration, thereby slowing ossification progression; (2) Enhanced cervical stability: The ipsilateral group exhibited less postoperative loss of C2-7 Cobb angle, indicating better cervical stability—a factor that may inhibit further ossification growth. This study also found that the contralateral group had greater postoperative loss of C2-7 Cobb angle than the ipsilateral group. On one hand, this may stem from more extensive damage to the posterior cervical muscles in the contralateral group (performed to achieve additional decompression during surgery), leading to insufficient muscular compensation. On the other hand, it may be attributed to the relatively short follow-up duration. Existing research has established that preoperative C2-7 SVA correlates with the prognosis of C-OPLL patients after laminoplasty. Patients with high preoperative C2-7 SVA face a significantly higher risk of cervical sagittal imbalance and cervical neurological symptoms; thus, C2-7 SVA serves as a valid prognostic indicator for prognosis of C-OPLL patients undergoing laminoplasty. In this study, no statistically significant differences were observed between the two groups in preoperative C2-7 SVA, postoperative C2-7 SVA, or the magnitude of C2-7 SVA increase. This similarity may be due to all patients receiving the same surgical procedure. Cha et al. [ 17 ] reported that in 30 patients who underwent open-door laminoplasty with lateral mass anchor screws, the average anteroposterior diameter of the spinal canal increased significantly from 7.51 ± 1.79 mm preoperatively to 13.98 ± 1.80 mm at the 1-year follow-up. Consistent with these findings, our study showed increased spinal cord diameter postoperatively in both groups: from 8.22 ± 0.81 mm to 15.30 ± 1.36 mm in the ipsilateral group, and from 8.25 ± 0.90 mm to 14.15 ± 0.64 mm in the contralateral group. Notably, the increase was more pronounced in the ipsilateral group, suggesting that selecting a door-opening side aligned with the larger ossification-occupied area is more favorable. C5 nerve root palsy is a relatively common complication following posterior cervical surgery, with an incidence of 8.57% (3/35) in this study. Its pathogenesis may involve intraoperative nerve root traction, spinal cord migration, or impaired blood supply. Clinically, C5 nerve root palsy primarily presents as postoperative weakness of the deltoid and biceps brachii muscles, accompanied by dysfunction in shoulder abduction and elbow flexion [ 18 ]. In our study, the incidence of C5 nerve root palsy was 10% in the ipsilateral group and 6.67% in the contralateral group, with no statistically significant difference. Although rare, C5 nerve root palsy substantially impacts patients’ quality of life. Thus, excessive nerve root traction should be avoided intraoperatively, and early postoperative detection—combined with neurotrophic medication and rehabilitation training—should be implemented when palsy occurs. Axial symptoms are among the most prevalent complications after posterior cervical surgery, occurring in 17.14% (6/35) of patients in this study. These symptoms, characterized by neck and shoulder pain, stiffness, and limited range of motion, may result from extensive intraoperative dissection of paravertebral muscles, reduced cervical mobility, or facet joint injury [ 19 ]. The incidence of axial symptoms was 20% in the ipsilateral group and 13.33% in the contralateral group, with no statistically significant difference. While most axial symptoms are self-limiting, they significantly hinder postoperative recovery and reduce quality of life. To lower their incidence, surgeons should minimize the scope of muscle dissection intraoperatively, and patients should undergo early neck and shoulder functional exercises postoperatively. CSF leakage is a serious spinal surgery complication; no cases were observed in this study. However, literature reports an incidence of 1%–17% [ 20 – 21 ], primarily associated with dural injury or adhesion between ossification and the dura mater. CSF leakage can lead to postoperative complications such as headache and incisional infection. Therefore, careful dissection of ossification from the dura mater is essential intraoperatively. If dural injury is detected, immediate repair is required, with biological fibrin glue or fascia coverage used if necessary. Postoperative laminoplasty closure—defined as failure to maintain the lamina in an open state after door-opening, leading to recurrent spinal canal stenosis—was not observed in this study. However, literature cites an incidence of approximately 10% [ 22 ], which may result from hinge-side fractures, inadequate fixation, or excessive cervical movement postoperatively. To prevent this, surgeons should ensure appropriate width of the hinge-side bone groove, use reliable fixation techniques (e.g., mini-plates or anchors) to keep the lamina open, and advise patients to wear a cervical collar postoperatively to restrict cervical movement. No significant differences in postoperative complications—including C5 nerve root palsy, axial symptoms, and transient deltoid pain—were found between the two groups. This indicates that selecting a door-opening side aligned with the ossification-occupied area does not increase the risk of surgical complications. Kaneyama et al. [ 23 ] reported a higher incidence of C5 nerve root palsy after single-door laminoplasty than double-door laminoplasty, potentially due to asymmetric spinal cord migration. In our study, however, the incidence of C5 nerve root palsy and axial symptoms did not differ significantly between the two groups. Notably, transient deltoid pain (innervated by the C5 nerve root) was more prominent in the ipsilateral group, likely due to more significant posterior spinal cord migration in this group. The ipsilateral group also had a slightly higher incidence of postoperative axial symptoms than the contralateral group (20% vs 13.33%). While this difference was not statistically significant, it merits attention in clinical practice. Given that axial symptoms may be linked to reduced postoperative cervical mobility, minimizing intraoperative damage to posterior cervical structures is recommended to lower their incidence. Limitations This study has several limitations. First, the sample size was small; therefore, caution should be exercised when generalizing these findings to a larger population. Second, this retrospective study only included a small number of patients from a single institution, and further research with larger multi-center cohorts is needed. Third, we only selected patients treated by the same orthopedic surgeon to control the impact of surgical techniques on the results. Finally, the follow-up period of this study was relatively short. Conclusion The results of this study suggest that for patients with multi-segment asymmetric C-OPLL, the surgical strategy of selecting a door-opening side consistent with the side of the larger ossification-occupied area has advantages in improving neurological function, expanding the cervical spinal canal sagittal diameter, and delaying ossification progression. This finding provides an important basis for clinical surgical decision-making. However, the optimization of surgical strategies still needs to be combined with the specific conditions of patients, including the type and scope of ossification, and the degree of spinal cord compression. Declarations Ethics approval and consent to participate The Ethics Review Committee of the First Affiliated Hospital of Anhui University of Science and Technology; The First Affiliated Hospital of Anhui University of Technology The Ethics Review Committee of the First Affiliated Hospital of Anhui University of Science and Technology approved the conduct of this study. All patients and their families gave written informed consent. The design of this study complies with the 1964 Helsinki Declaration and its subsequent amendments, as well as comparable ethical standards. Consent for the publication of identifying images or other personal or clinical details of participants that compromise anonymity：Not Applicable Project fund: Supported by “Research Funds of Joint Research Center for Occupational Medicine and Health of IHM”(NO.OMH-2023-28). Consent for publication All authors agree to submit this paper for publication. Availability of data and materials The data and materials that support the findings of this study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no conflict of interest. References Chen Z, Liu B, Dong J, et al. Comparison of anterior corpectomy and fusion versus laminoplasty for the treatment of cervical ossification of posterior longitudinal ligament: a meta-analysis. Neurosurg Focus. 2016;40(6):E8. Sun N, Jiang C, Liu Y. Surgical options for ossification of the posterior longitudinal ligament of the cervical spine: a narrative review. J Orthop Surg Res. 2024;19(1):707. Qin R, Chen X, Zhou P, Li M, Hao J, Zhang F. Anterior cervical corpectomy and fusion versus posterior laminoplasty for the treatment of oppressive myelopathy owing to cervical ossification of posterior longitudinal ligament: a meta-analysis. Eur Spine J. 2018;27(6):1375–87. Qin R, Chen X, Zhou P, Li M, Hao J, Zhang F. Anterior cervical corpectomy and fusion versus posterior laminoplasty for the treatment of oppressive myelopathy owing to cervical ossification of posterior longitudinal ligament: a meta-analysis. Eur Spine J. 2018;27(6):1375–87. Xu P, Zhuang JS, Huang YS, Tu C, Chen JT, Zhong ZM. Surgical outcomes of cervical myelopathy due to ossification of posterior longitudinal ligament: Anterior decompression and fusion versus posterior laminoplasty. J Orthop Surg (Hong Kong). 2019;27(2):2309499019837907. Zhang J, Liang Q, Qin D, et al. The anterior versus posterior approach for the treatment of ossification of the posterior longitudinal ligament in the cervical spine: A systematic review and meta-analysis. J Spinal Cord Med. 2021;44(3):340–9. Hirabayashi K, Toyama Y, Chiba K. Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament. Clin Orthop Relat Res. 1999;(359):35–48. Hou Y, Liang L, Shi GD, Xu P, Xu GH, Shi JG, Yuan W. Comparing effects of cervical anterior approach and laminoplasty in surgical management of cervical ossification of posterior longitudinal ligament by a prospective nonrandomized controlled study. Orthop Traumatol Surg Res. 2017;103(5):733–40. Zhang Q, Guo R, Fang S, Tong S, Fan Y, Wang J. The clinical efficacy of laminectomy fusion fixation and posterior single open-door laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL): a retrospective study. BMC Surg. 2023;23(1):380. Basu S, Gohil K. Comparing Spinal Cord Drift, Clinical Outcomes and C5 Palsy in Degenerative Cervical Myelopathy: A Study of Cervical Laminoplasty Versus Laminectomy/Fusion. Global Spine J. 2025;15(2):1277–87. Sodeyama T, Goto S, Mochizuki M, Takahashi J, Moriya H. Effect of decompression enlargement laminoplasty for posterior shifting of the spinal cord. Spine (Phila Pa 1976). 1999;24(15):1527–31. discussion 1531-2. Kang MS, Kim KH, Park JY, Kuh SU, Chin DK, Kim KS, Jin BH, Cho YE. Progression of Cervical Ossification of Posterior Longitudinal Ligament After Laminoplasty or Laminectomy With Posterior Fixation. Clin Spine Surg. 2019;32(9):363–8. Wang L, Jiang Y, Li M, Qi L. Postoperative Progression of Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review. World Neurosurg. 2019;126:593–600. Lee JJ, Shin DA, Yi S, Kim KN, Yoon DH, Shin HC, Ha Y. Effect of posterior instrumented fusion on three-dimensional volumetric growth of cervical ossification of the posterior longitudinal ligament: a multiple regression analysis. Spine J. 2018;18(10):1779–86. Xu C, Zhang Y, Dong M, Wu H, Yu W, Tian Y, Cao P, Chen H, Wang X, Shen X, Liu Y, Yuan W. The relationship between preoperative cervical sagittal balance and clinical outcome of laminoplasty treated cervical ossification of the posterior longitudinal ligament patients. Spine J. 2020;20(9):1422–9. Cha JR, Kim HW, Yang DG, Chung HY, Hwang IY. Open-Door Laminoplasty Using Lateral Mass Anchoring Screws and Nonabsorbable Sutures in Patients with Multilevel Cervical Myelopathy. Clin Orthop Surg. 2020;12(4):477–84. Khuyagbaatar B, Kim K, Purevsuren T, Lee SH, Kim YH. Biomechanical Effects on Cervical Spinal Cord and Nerve Root Following Laminoplasty for Ossification of the Posterior Longitudinal Ligament in the Cervical Spine: A Comparison Between Open-Door and Double-Door Laminoplasty Using Finite Element Analysis. J Biomech Eng. 2018;140(7). 10.1115/1.4039826 . Khuyagbaatar B, Kim K, Park WM, Kim YH. Biomechanical investigation of post-operative C5 palsy due to ossification of the posterior longitudinal ligament in different types of cervical spinal alignment. J Biomech. 2017;57:54–61. Lee SE, Chung CK, Jahng TA, Kim HJ. Long-term outcome of laminectomy for cervical ossification of the posterior longitudinal ligament. J Neurosurg Spine. 2013;18(5):465–71. Strömqvist F, Jönsson B, Strömqvist B. Swedish Society of Spinal Surgeons. Dural lesions in lumbar disc herniation surgery: incidence, risk factors, and outcome. Eur Spine J. 2010;19(3):439–42. Amoozegar F. Spinal Cerebrospinal Fluid Leaks/Intracranial Hypotension. Neurosurg Clin N Am. 2025;36(2):299–309. Chen G, Luo Z, Nalajala B, Liu T, Yang H. Expansive open-door laminoplasty with titanium miniplate versus sutures. Orthopedics. 2012;35(4):e543–8. Kaneyama S, Sumi M, Kanatani T, Kasahara K, Kanemura A, Takabatake M, Nakatani T, Yano T. Prospective study and multivariate analysis of the incidence of C5 palsy after cervical laminoplasty. Spine (Phila Pa 1976). 2010;35(26):E1553–8. Tables Table 1 Comparison of Baseline Characteristics Between Groups Age (years) Sex (male: female) BMI (kg/m2) Operative time (min) Intraoperative blood loss (ml) Contralateral group (N = 15) 59.53 ± 6.64 9 (60) : 6 (40) 24.89 ± 1.21 129.33 ± 9.61 150.67 ± 11.32 Concordant group (N = 20) 60.20 ± 9.47 13 (65) : 7 (35) 24.6.00 ± 1.72 129.5.00 ± 10.99 151.00 ± 13.44 t/χ2 0.245 < 0.001 -0.589 0.048 0.080 P 0.808 0.999 0.560 0.962 0.937 Table 2. Comparison of Clinical Outcomes Between Groups Contralateral group (N = 15) Concordant group (N = 20) t P VAS Preoperative 3.67 ± 1.05 3.60 ± 1.05 -0.187 0.853 1-Year Postoperative 1.73 ± 0.59 1.80 ± 0.77 0.290 0.774 t 6.223 6.203 P < 0.001 < 0.001 JOA Preoperative 10.00 ± 1.36 9.80 ± 1.77 -0.378 0.708 1-Year Postoperative 12.73 ± 0.70 14.30 ± 1.66 3.795 < 0.001 t -6.902 -8.311 P < 0.001 < 0.001 NDI Preoperative 37.33 ± 1.99 37.20 ± 3.55 -0.141 0.889 1-Year Postoperative 9.33 ± 2.06 9.30 ± 2.08 -0.047 0.963 t 30.337 37.892 P < 0.001 < 0.001 Table 3 Comparison of Radiographic Outcomes Between Groups Contralateral group (N = 15) Concordant group (N = 20) t P C2-7 Cobb angle (°) Preoperative 17.84 ± 2.70 17.82 ± 4.58 -0.016 0.987 1-Year Postoperative 13.47 ± 0.98 14.96 ± 2.60 0.290 0.774 t 2.431 5.898 P 0.021 < 0.001 Spinal canal sagittal diameter (mm) Preoperative 8.25 ± 0.90 8.22 ± 0.81 -0.113 0.911 1-Year Postoperative 14.15 ± 0.64 15.30 ± 1.36 3.795 < 0.001 t -20.004 -20.608 P < 0.001 < 0.001 C2-7SVA (mm) Preoperative 16.72 ± 0.94 16.62 ± 0.91 -0.300 0.766 1-Year Postoperative 25.26 ± 1.03 25.17 ± 1.24 -0.234 0.817 t 30.337 37.892 P < 0.001 < 0.001 Change in C2-7 SVA (mm) 8.54 ± 1.00 8.54 ± 1.52 0.012 0.991 Table 4 Comparison of Ossification Characteristics Between Groups Change in ossification longitudinal length (mm) Change in ossification thickness (mm) Contralateral group (N = 15) 2.24 ± 0.33 1.56 ± 0.08 Concordant group (N = 20) 1.85 ± 0.32 1.49 ± 0.13 t 3.526 2.146 P 0.001 0.040 Table 5. Comparison of postoperative adverse events between groups Transient pain in the deltoid region C5 nerve root palsy Axial symptoms Total complication rate Contralateral group (N = 15) 3 (20.00) 1 (6.67) 2 (13.33) 6 (13.33) Concordant group (N = 20) 9 (45.00) 2 (10.00) 4 (20.00) 15 (25.00) χ2 - - - 2.188 P 0.808 0.999 0.560 0.139 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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1","display":"","copyAsset":false,"role":"figure","size":141638,"visible":true,"origin":"","legend":"\u003cp\u003eBased on imaging characteristics, ossification of the posterior longitudinal ligament (OPLL) was classified into four subtypes: (1) Continuous type (linear ossification spanning multiple vertebral segments); (2) Segmental type (discrete ossified lesions at multiple vertebral posterior margins with preserved normal ligament intervals between segments); (3) Focal type (localized ossification confined to a single vertebral segment); (4) Mixed type (exhibiting features of both continuous and segmental types).\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7663372/v1/c447dc0c81924b23dfe0bd9a.png"},{"id":95807013,"identity":"4e18ad54-d559-4e6b-8cad-a649d5269a3e","added_by":"auto","created_at":"2025-11-13 08:48:03","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":131220,"visible":true,"origin":"","legend":"\u003cp\u003eFigure a demonstrates the preoperative classification of ossification, while Figure b shows the 1-year postoperative classification.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7663372/v1/c3b399491cd02034a99bdfb4.png"},{"id":95806773,"identity":"52658fa3-3e8d-4f7c-9ebe-ddf529fded6c","added_by":"auto","created_at":"2025-11-13 08:47:52","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1094532,"visible":true,"origin":"","legend":"\u003cp\u003ePanels A-E represent preoperative imaging examinations, while panels F-H show the 1-year postoperative follow-up imaging studies. In panels A, C, and E, K-line positivity (+) was observed, with no signal enhancement detected on T2-weighted imaging (T2WI). Panel D demonstrates larger ossification occupation on the left side (on MRI coronal images, the midsagittal line through the thickest portion of OPLL divides the ossified structure into major and minor sides). Compared with panel A, panel G at 1-year follow-up shows decreased C2-7 Cobb angle. In panel H, the open-door side is on the right, contralateral to the side with larger ossification occupation, indicating increased sagittal diameter of the cervical canal.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7663372/v1/b93977b26182b1a84cff9d2b.png"},{"id":100563541,"identity":"168b4dc1-3eeb-4cc3-843b-e16fb41e3ff3","added_by":"auto","created_at":"2026-01-19 08:46:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2676922,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7663372/v1/7100dee7-cb3b-40f3-a75c-2a07e136a440.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of Door-Opening Side Selection on Surgical Outcomes in single-door cervical laminoplasty for Asymmetric Ossification of the Posterior Longitudinal Ligament","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCervical ossification of posterior longitudinal ligament (C-OPLL) is a multifactorial disease characterized by progressive heterotopic ossification and calcification of the posterior longitudinal ligament. It can lead to cervical spinal canal stenosis, as well as compression of the spinal cord and nerve roots. The symptoms include neck pain, limited mobility, limb numbness, and motor dysfunction, and severe cases often require surgical treatment [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].Since the 20th century, with the widespread application of electronic devices and the rise of short-video platforms in recent years, behavioral patterns such as maintaining a head-down posture for a long time when using mobile devices and working at desks have contributed to a significant younger trend in the onset of cervical spondylosis. In this context, C-OPLL has become an important pathogenic factor of cervical spondylosis.\u003c/p\u003e\u003cp\u003eClinical studies have shown that patients with symptoms lasting more than 23 months tend to have a poor postoperative prognosis and require timely surgical intervention [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Orthopedic surgeons usually choose the side with the most obvious symptoms and signs to treat C-OPLL patients. However, in asymmetric C-OPLL cases where the more symptomatic side contralateral to the predominant OPLL occupation, no consensus exists regarding optimal laminoplasty side selection.\u003c/p\u003e\u003cp\u003eIn this study, we retrospectively analyzed imaging data (CT, MRI, and radiographs) and surgical outcomes from 35 patients with multilevel asymmetric C-OPLL undergoing laminoplasty with different opening approaches, to determine the optimal decompression side for open-door laminoplasty in multilevel asymmetric C-OPLL.\u003c/p\u003e\u003cp\u003eHowever, for asymmetric C-OPLL, when the side with more severe symptoms and signs is on the opposite side of the side with a larger ossification-occupied area, there is currently no research to determine which side should be the opening side. Based on this, in this study, we attempted to determine the optimal opening side for single-door laminoplasty in the treatment of multi-segment asymmetric C-OPLL by retrospectively analyzing the CT, MRI and X-ray data of 35 patients with multi-segment asymmetric C-OPLL and the surgical results of each opening side.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003ePatients\u003c/h2\u003e\n\u003cp\u003eThis retrospective study enrolled 35 consecutive C-OPLL patients who met the inclusion criteria between September 2020 and January 2024, all with complete clinical documentation and follow-up data.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eInclusion criteria were:\u003c/h3\u003e\n\u003cp\u003e(1) Patients with sC-OPLL who meet the surgical criteria;\u003c/p\u003e\n\u003cp\u003e(2) Patients whose ossified lesions involve 3 or more spinal segments and are K-line positive;\u003c/p\u003e\n\u003cp\u003e(3) Patients with asymmetric C-OPLL confirmed by radiographic examination;\u003c/p\u003e\n\u003cp\u003e(4) Patients in whom the side with more severe symptoms and signs is contralateral to the side with a larger occupied area by ossification;\u003c/p\u003e\n\u003cp\u003e(5) Patients who only underwent posterior cervical single-door laminoplasty;\u003c/p\u003e\n\u003cp\u003e(6) Patients with a postoperative follow-up duration of more than 1 year and complete data.\u003c/p\u003e\n\u003ch3\u003eExclusion Criteria were:\u003c/h3\u003e\n\u003cp\u003e(1) Patients who do not meet the above inclusion criteria;\u003c/p\u003e\n\u003cp\u003e(2) Patients with similar symptoms and signs on both sides;\u003c/p\u003e\n\u003cp\u003e(3) Patients with similar occupied areas by ossification on both sides;\u003c/p\u003e\n\u003cp\u003e(4) Patients with a history of infection, malignant tumor, or severe trauma;\u003c/p\u003e\n\u003cp\u003e(5) Patients with neurological diseases (including fractures, dislocations, syringomyelia, poliomyelitis, spinal cord tumors, Parkinson's disease, ankylosing spondylitis, cervical spine infection, etc.) or a history of cervical spine surgery;\u003c/p\u003e\n\u003cp\u003e(6) Patients with a history of substance abuse;\u003c/p\u003e\n\u003cp\u003e(7) Patients who refuse to participate in follow-up.\u003c/p\u003e\n\u003ch3\u003eClinical and Radiologic Assessment\u003c/h3\u003e\n\u003cp\u003eThe study was conducted through a retrospective review of all patients. The study cohort consisted of 22 male and 13 female patients,with an age range of42-75 years (mean age: 59.91 years). Patients were assigned to the ipsilateral group when the door-opening side was consistent with the side of the larger ossification-occupied area; when the door-opening side was inconsistent with the side of the larger ossification-occupied area, patients were assigned to the contralateral group.\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eThe ipsilateral group (n\u0026thinsp;=\u0026thinsp;20) included 13 male patients and 7 female patients, with an age range of 42\u0026ndash;75 years (mean age: 60.20\u0026thinsp;\u0026plusmn;\u0026thinsp;9.47 years), a disease duration of 7\u0026ndash;45 months (mean duration: 39.91\u0026thinsp;\u0026plusmn;\u0026thinsp;1.47 months), 4 cases complicated with hypertension, and 3 cases complicated with diabetes mellitus.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u0026bull;The Contralateral Group (n\u0026thinsp;=\u0026thinsp;15) was composed of 9 male patients and 6 female patients, with an age range of 48\u0026ndash;68 years (mean age: 59.53\u0026thinsp;\u0026plusmn;\u0026thinsp;6.64 years), a disease duration of 9\u0026ndash;50 months (mean duration: 42.28\u0026thinsp;\u0026plusmn;\u0026thinsp;2.23 months), 3 cases complicated with hypertension, and 2 cases complicated with diabetes mellitus.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eStatistical analysis of baseline data showed that there were no statistically significant differences between the two groups in parameters such as age, gender distribution, body mass index (BMI), and composition of underlying diseases (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), indicating good comparability between the groups. This study was reviewed and approved by the Ethics Committee of our hospital (Approval No.: 2025-KY-Y016-001).\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eAll asymmetric C-OPLL patients underwent comprehensive cervical spine imaging including radiographs, Three-dimensional computed tomography (3D-CT) and Magnetic resonance imaging (MRI). Based on imaging characteristics, OPLL lesions were classified into four subtypes[\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e]: 1. Continuous type (bridging ossification across multiple vertebral levels) 2. Segmental type (non-contiguous ossifications at posterior vertebral margins with preserved ligament integrity between segments) 3. Focal type (localized ossification within a single vertebral level) 4. Mixed type (exhibiting both continuous and segmental characteristics). Figure\u0026nbsp;1To determine the optimal surgical approach, a comprehensive evaluation was conducted, incorporating ossification type, the severity of spinal canal stenosis, the site of spinal cord compression, and clinical symptoms. All patients underwent posterior cervical open-door laminoplasty, followed by postoperative radiographic assessment.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003ch3\u003eClinical assessment\u003c/h3\u003e\n\u003cp\u003eGender, age, and body mass index (BMI) were recorded as baseline characteristics. Intraoperative blood loss (milliliters, mL) and surgical duration (minutes) were all included in the baseline data.\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eAxial pain was quantitatively evaluated using the Visual Analog Scale (VAS);\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eSpinal nerve function was assessed via the Japanese Orthopaedic Association\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eThe Neck Disability Index (NDI) was used to evaluate the impact of cervical spine problems on daily life.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eData on VAS, JOA, and NDI scores were all collected preoperatively and at the 1-year postoperative follow-up. Cervical spine imaging parameters (including spinal canal sagittal diameter, C2-7 Cobb angle, C2-7sagittal vertical axis (SVA), ossification length and thickness, and spinal cord shift) were also collected preoperatively and at the 1-year postoperative follow-up. Radiographic measurement parameters were defined as follows: The C2-7 Cobb angle (the acute angle formed by the intersection of lines perpendicular to the inferior endplates of C2 and C7 on lateral radiographs) Ossification length and thickness were measured as follows: For axial length measurement, on CT bone window sagittal images, a line segment was drawn from the cephalad to caudal ends of the ossification. For discontinuous or irregular ossifications, multiple segments were measured along the longest diameter of each ossified segment, with the total length calculated as the sum of all segments. The thickness measurement protocol was as follows: At point a (the intersection of the spinal canal and the thickest portion of ossification), a line parallel to the posterior vertebral border was drawn. From point a, a perpendicular line to the posterior vertebral border was constructed, intersecting the border or its extension at point b. The distance between points a and b was defined as the ossification thickness. The sagittal diameter of the spinal canal was measured on axial CT images as the shortest distance from the midpoint of the posterior vertebral border to the corresponding posterior spinal canal wall, with the final value representing the average across all measured segments. The C2-7 sagittal vertical axis (SVA) was determined on lateral cervical radiographs by measuring the vertical distance between a plumb line dropped from the midpoint of the C2 vertebral body and the posterosuperior corner of C7. The SVA increase was calculated as the postoperative SVA minus preoperative SVA, with greater increases indicating worse sagittal alignment of the cervical spine.\u003c/p\u003e\n\u003cp\u003eThe definitions of radiological measurement parameters are as follows:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cem\u003e1.\u003c/em\u003eC2-7 Cobb angle: On lateral radiographs, two lines perpendicular to the inferior endplates of the C2 and C7 vertebrae are drawn respectively; the acute angle formed by the intersection of these two lines is defined as the C2-7 Cobb angle.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cem\u003e2.\u003c/em\u003eMeasurement methods for ossification length and thickness:\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eLength measurement: On sagittal images of CT bone windows, a line segment is drawn from the cephalad to the caudal end of the ossification, and the length is measured directly. For discontinuous or irregular ossifications, measurements are taken along the longest diameter of each ossified segment separately, and the total length is calculated as the sum of all segments.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eThickness measurement: First, identify Point A (the intersection of the spinal canal and the thickest part of the ossification), and draw a line parallel to the posterior vertebral border through Point A. Then, draw a line perpendicular to the posterior vertebral border from Point A, which intersects the posterior vertebral border or its extension at Point B. The distance between Points A and B is defined as the ossification thickness.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cem\u003e3.\u003c/em\u003eSpinal canal sagittal diameter: On axial CT images, measure the shortest distance from the midpoint of the posterior vertebral border to the corresponding posterior wall of the spinal canal; the final result is the average value of all measured segments.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cem\u003e4.\u003c/em\u003eC2-7 sagittal vertical axis (SVA): On lateral cervical radiographs, a plumb line is drawn downward from the midpoint of the C2 vertebral body; the vertical distance between this plumb line and the posterosuperior corner of the C7 vertebral body is defined as the C2-7 SVA.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cem\u003e5.\u003c/em\u003eSVA increase value: Calculated using the formula \"Postoperative SVA value - Preoperative SVA value\". A larger increase indicates worse sagittal alignment of the cervical spine.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003c/div\u003e\n\u003ch3\u003eSurgical technique\u003c/h3\u003e\n\u003cp\u003ePrior to surgery, the patient underwent skin preparation of the head and neck surgical area. After general anesthesia induction, the patient was placed in a prone position, with the forehead and face fixed using a silicone ring, and the neck maintained in a moderate forward flexion position. Soft protective pads were applied to the anterior chest wall, bilateral anterior superior iliac spines, and knee joint areas. Following routine disinfection and draping of the surgical field, a single-door laminoplasty was performed (taking the C3-C6 segments as an example). A midline posterior cervical incision was made, extending from the external occipital protuberance to the C7 spinous process. The skin, subcutaneous tissue, and ligamentum nuchae were divided in layers. After retractor placement, subperiosteal dissection was performed to expose the C3\u0026ndash;C6 laminae, spinous processes, and lateral mass joints. A high-speed burr was used to grind away the outer cortex of the C3-C6 laminae on one side, while preserving the inner cortex to form a 0.3 cm-wide bone groove (serving as the \"hinge\" for the single-door procedure).. An ultrasonic bone scalpel was then used to make a full-thickness incision on the other side of the C3-C6 laminae. The entire length of the C3-C6 laminae was lifted toward one side, maintaining an 8 mm gap between the broken ends of the laminae on the opposite side. Intraoperatively, after confirming satisfactory door-opening and adequate spinal canal decompression, internal fixation titanium plates were placed between the fractured ends of the C3, C4, C5, and C6 laminae (post-door-opening) to maintain the lifted position and stability of the C3-C6 laminae. After irrigation and hemostasis, autograft bone harvested from the spinous processes and laminar grooves was morselized into 2\u0026ndash;3 mm particles and packed into the hinge site to promote bony fusion. A drainage tube was placed, and layered closure of deep fascia, superficial fascia, subcutaneous tissue, and skin was performed. The incision was covered with sterile dressing. All procedures were performed by the same senior spine surgeon.\u003c/p\u003e\n\u003ch3\u003ePostoperative Management\u003c/h3\u003e\n\u003cp\u003eAfter surgery, patients were routinely administered antibiotics for 48 hours to prevent infection, supplemented with neurotrophic agents, glucocorticoids, non-steroidal anti-inflammatory drugs (NSAIDs), and dehydrating agents for 3\u0026ndash;6 days. For patients with cerebrospinal fluid (CSF) leakage, the drainage device was retained for 7\u0026ndash;9 days and removed when the 24-hour drainage volume was less than 30 mL. Starting from the 2nd postoperative day, patients were instructed to gradually ambulate under the protection of a cervical collar and with the supervision of family members. After 4 weeks of cervical collar fixation, patients were guided to perform cervical spine flexion and extension functional exercises. Before discharge, patients were advised to return to the hospital regularly for reexaminations of imaging findings and functional assessments.\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eStatistical analysis\u003c/h2\u003e\n\u003cp\u003eSPSS 26.0 statistical software was used for data analysis. The Shapiro-Wilk normality test was conducted on continuous variables such as JOA scores, VAS scores, and cervical curvature. Data that conformed to a normal distribution were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (x̄ \u0026plusmn; s). For indicators related to ossification, the independent samples t-test was applied when the assumptions of normal distribution and homogeneity of variance were satisfied; if the variance was heterogeneous, the Wilcoxon rank-sum test was used instead. For categorical variables including axial symptoms, CSF leakage, and C5 nerve root palsy, the data were described in the form of frequency (percentage) and analyzed using the chi-square test. A P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered to indicate a statistically significant difference.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eDemographics\u003c/h2\u003e\u003cp\u003eAnalysis of baseline data revealed no statistically significant differences between the two groups of patients in parameters including age, gender distribution, and BMI (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eClinical outcomes\u003c/h2\u003e\u003cp\u003eAt 1-year follow-up, the VAS scores of patients in both groups were significantly lower than those before surgery, with statistically significant differences (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). There were no statistically significant differences in VAS scores between the ipsilateral group and the contralateral group either before surgery or at the 1-year follow-up (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003eThe JOA scores of patients in both groups were significantly higher at 1 year postoperatively than preoperatively (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Inter-group comparisons revealed the following:\u003c/p\u003e\u003cp\u003e① There was no statistically significant difference in preoperative JOA scores between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05);\u003c/p\u003e\u003cp\u003e② At 1-year postoperative follow-up, the JOA score of the ipsilateral group was significantly higher than that of the contralateral group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), suggesting that the ipsilateral group had a superior clinical outcome in terms of neurological function recovery;\u003c/p\u003e\u003cp\u003eAdditionally, there were no statistically significant differences in NDI scores between the two groups either before surgery or at 12 months 1-year follow-up (both P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;2).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eRadiological Results\u003c/h2\u003e\u003cp\u003eAs shown in Table\u0026nbsp;3, all C2-C7 Cobb angle, spinal canal sagittal diameter, and C2-C7 SVA measurements passed normality (Shapiro-Wilk) and homogeneity of variance (Levene's) tests, permitting independent samples t-tests for intergroup comparisons. The results showed that:1) Both groups showed significant reduction in C2-C7 Cobb angle at 1-year follow-up compared with baseline values (both p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) .2) The contralateral group exhibited greater Cobb angle loss than the ipsilateral group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), indicating more deterioration of sagittal alignment stability. 3) Both groups achieved significant increases in spinal canal sagittal diameter (both p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). 4) The ipsilateral group demonstrated greater diameter expansion than the contralateral group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), suggesting superior anatomical restoration of canal volume. 5) Both groups showed significant C2-C7 SVA increases at 1-year follow-up (both p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). 6) No significant intergroup difference in SVA change was observed (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), suggesting equivalent impact on sagittal balance regardless of surgical approach side (Table\u0026nbsp;3).\u003c/p\u003e\u003cp\u003eAt 1-year follow-up, the axial length and thickness of the ossification increased significantly in patients of both groups. Among them, the changes in axial length and thickness of the ossification in the contralateral group were greater than those in the ipsilateral group, with statistically significant differences (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAs classified in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e using established radiographic criteria, ossification of the posterior longitudinal ligament (OPLL) was categorized into four subtypes: Baseline subtype distribution: Consistent group: Segmental (n\u0026thinsp;=\u0026thinsp;2), Focal (n\u0026thinsp;=\u0026thinsp;3), Mixed (n\u0026thinsp;=\u0026thinsp;5), Continuous (n\u0026thinsp;=\u0026thinsp;10). Contralateral group: Segmental (n\u0026thinsp;=\u0026thinsp;2), Focal (n\u0026thinsp;=\u0026thinsp;2), Mixed (n\u0026thinsp;=\u0026thinsp;4), Continuous (n\u0026thinsp;=\u0026thinsp;7). At 1-year follow-up, both groups showed: Significant dimensional changes in thickness/axial length (both p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This suggests surgical approach selection (consistent vs contralateral) does not significantly influence OPLL subtype progression.\u003c/p\u003e\u003cp\u003eRadiological follow-up data revealed the distribution of preoperative ossification types in the ipsilateral group: 2 cases of segmental type, 3 cases of focal type, 5 cases of mixed type, and 10 cases of continuous type. For the contralateral group, the preoperative ossification type distribution was as follows: 2 cases of segmental type, 2 cases of focal type, 4 cases of mixed type, and 7 cases of continuous type.​ At the 1-year postoperative evaluation, the ossification foci in both groups exhibited changes in thickness and axial length, with no significant evolution in ossification types observed (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). This finding suggests that the selection of the door-opening side bears no direct correlation to the transformation of ossification types (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eComplications\u003c/h2\u003e\u003cp\u003eNone of the 35 patients developed intraspinal hematoma, spinal cord injury, CSF leakage, postoperative laminoplasty closure, or postoperative kyphosis. In the ipsilateral group: there were 4 cases of postoperative axial symptoms (20%), 2 cases of C5 nerve root palsy (10%), and 9 cases of transient pain in the deltoid region (45%), with an overall complication rate of 25%.​ In the contralateral group: there were 2 cases of postoperative axial symptoms (13.33%), 1 case of C5 nerve root palsy (6.67%), and 3 cases of transient pain in the deltoid region (20%), with an overall complication rate of 13.33%.​ No significant differences were observed between the two groups in the incidences of C5 nerve root palsy, transient pain in the deltoid region, axial symptoms, or the overall complication rate (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eTypical cases\u003c/h2\u003e\u003cp\u003eThe patient is a 69-year-old male. He has experienced numbness and weakness in his left upper limb for 4 years, and the symptoms have worsened, accompanied by weakness in both lower limbs and unsteady walking for 6 months. After admission, comprehensive examinations were conducted to rule out surgical contraindications. Under general anesthesia, a posterior cervical single-door laminoplasty was performed to expand the spinal canal. Postoperative re-examination showed that the volume of the spinal canal was significantly expanded, the spinal cord was decompressed adequately, and the neurological function improved significantly compared to before the operation(Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eC-OPLL is a chronic progressive disorder characterized by heterotopic ossification of the cervical posterior longitudinal ligament, which often leads to spinal cord compression and neurological dysfunction. Posterior decompression surgery is currently the preferred treatment for most patients with long-segment C-OPLL in clinical practice[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Posterior cervical surgical approaches include laminoplasty (LAMP), laminectomy (LAME), and the emerging posterior hybrid technique. Among these, LAMP remains the most widely used surgical method for C-OPLL [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Among the derived techniques of LAMP, the single-door laminoplasty has the widest clinical application[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This technique expands the spinal canal volume by unilaterally lifting the laminae at multiple segments, utilizing cervical lordosis and the \"bowstring effect\" to facilitate posterior spinal cord migration, thereby avoiding compression from the anterior ossification [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. It is widely recognized as a reliable surgical technique.\u003c/p\u003e\u003cp\u003eThe measurement of the occupied area by ossification of the posterior longitudinal ligament was one of the key measurement techniques in this study. However, unavoidable errors still exist, which can be attributed to the following factors. First, the \"partial volume effect\" of MRI may affect the accuracy of identifying the segments responsible for cervical spinal cord compression. Second, due to differences in imaging principles, the localization of relevant segments on MRI may not be completely consistent with that on the corresponding CT scans. Third, inherent errors exist in determining the mid-sagittal line of the spinal canal on axial CT images. Fourth, for the measurement of the left or right half of the ossified structure, we used image system recognition combined with manual auxiliary calculation to determine the occupied area; nevertheless, unavoidable measurement errors remain. To reduce measurement errors, two investigators independently conducted multiple measurements, and the results were averaged.\u003c/p\u003e\u003cp\u003eIn the present study, the postoperative JOA scores increased in both groups, which is consistent with the findings of Hou Y et al [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], indicating that single-door laminoplasty can effectively relieve spinal cord compression and improve neurological function. Notably, the improvement in JOA scores was more significant in the ipsilateral group than in the contralateral group, suggesting that selecting a door-opening side consistent with the side of the ossification-occupied area may be more conducive to neurological function recovery. Previous studies have identified K-line positivity, door-opening angle, and door-opening width as key determinants of JOA score improvement [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. At 12-month follow-up, the ipsilateral group demonstrated significantly greater increases in cervical spinal canal sagittal diameter compared to the contralateral group. Therefore, we speculate that the higher JOA scores in the ipsilateral group may be related to the more thorough decompression effect achieved during surgery. This is because when the door-opening side is consistent with the side of the ossification-occupied area, the surgery can more directly relieve the ventral compression of the spinal cord, resulting in more obvious posterior migration of the spinal cord, better spinal cord expansion, and more complete recovery of the spinal cord morphology\u0026mdash;thereby improving neurological function more effectively. These findings are consistent with the research results of Basu S [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and Sodeyama T [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] et al.\u003c/p\u003e\u003cp\u003ePreviously, evaluation of surgical efficacy for C-OPLL was limited to the degree of improvement in symptoms and neurological function, the incidence of postoperative complications, and changes in parameters such as cervical curvature and range of motion. With the deepening understanding of C-OPLL, the progression of ossification has been recognized as an important indicator for evaluating the long-term surgical efficacy and has gradually become a research focus among scholars [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Previous studies have observed that laminoplasty accelerates the progression of ossification in C-OPLL patients. Kang et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] followed 50 C-OPLL patients for 37.6\u0026thinsp;\u0026plusmn;\u0026thinsp;16.8 months and found that the ossification increased by an average of 1.53\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04 mm. A study by Wang et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] revealed that the incidence of postoperative ossification progression increased from 3.3% to 74.5%. In the present study, the axial length and thickness of ossification increased in all patients at 1-year follow-up, indicating that the ossification process of C-OPLL may continue to progress postoperatively. Specifically, the changes in axial length and thickness of ossification were 2.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33 mm and 1.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08 mm in the contralateral group, respectively, while those in the ipsilateral group were 1.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 mm and 1.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13 mm, respectively. The difference between the two groups was statistically significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), suggesting that selecting a door-opening side inconsistent with the side of the ossification-occupied area may accelerate the progression of ossification.\u003c/p\u003e\u003cp\u003eThe precise mechanism underlying C-OPLL progression has not been fully clarified. A study by Lee et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] suggested that it may be related to the following factors:​ (1) Biomechanical changes: After surgical decompression, the local stress distribution of the cervical spine changes, which may stimulate the further growth of ossification; (2) Inflammatory response: Surgical trauma may trigger a local inflammatory response, releasing various cytokines that promote osteoblast differentiation and bone matrix deposition; (3) Genetic factors: The pathogenesis of C-OPLL is closely related to genetic factors, and certain gene polymorphisms may affect the progression rate of ossification. Based on radiological manifestations, ossification of OPLL is categorized into four types: focal, segmental, continuous, and mixed [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In the present study, the distribution of ossification types was similar between the ipsilateral group and the contralateral group before surgery and at 1 year postoperatively. However, increases in the axial length and thickness of the ossification suggest that\u0026mdash;despite unchanged types\u0026mdash;the volume and scope of the ossification may still be expanding. This finding aligns with previous studies, confirming that the ossification process in C-OPLL is dynamic and progressive. Surgical intervention may influence ossification progression by modifying the local biomechanical environment and relieving spinal cord compression.\u003c/p\u003e\u003cp\u003eIn this study, ossification progressed more slowly in the ipsilateral group than in the contralateral group, potentially due to the following factors: (1) More thorough decompression: When the door-opening side aligns with the ossification-occupied area, surgery directly relieves spinal cord compression and reduces local stress concentration, thereby slowing ossification progression; (2) Enhanced cervical stability: The ipsilateral group exhibited less postoperative loss of C2-7 Cobb angle, indicating better cervical stability\u0026mdash;a factor that may inhibit further ossification growth. This study also found that the contralateral group had greater postoperative loss of C2-7 Cobb angle than the ipsilateral group. On one hand, this may stem from more extensive damage to the posterior cervical muscles in the contralateral group (performed to achieve additional decompression during surgery), leading to insufficient muscular compensation. On the other hand, it may be attributed to the relatively short follow-up duration.\u003c/p\u003e\u003cp\u003eExisting research has established that preoperative C2-7 SVA correlates with the prognosis of C-OPLL patients after laminoplasty. Patients with high preoperative C2-7 SVA face a significantly higher risk of cervical sagittal imbalance and cervical neurological symptoms; thus, C2-7 SVA serves as a valid prognostic indicator for prognosis of C-OPLL patients undergoing laminoplasty. In this study, no statistically significant differences were observed between the two groups in preoperative C2-7 SVA, postoperative C2-7 SVA, or the magnitude of C2-7 SVA increase. This similarity may be due to all patients receiving the same surgical procedure. Cha et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] reported that in 30 patients who underwent open-door laminoplasty with lateral mass anchor screws, the average anteroposterior diameter of the spinal canal increased significantly from 7.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79 mm preoperatively to 13.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80 mm at the 1-year follow-up. Consistent with these findings, our study showed increased spinal cord diameter postoperatively in both groups: from 8.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81 mm to 15.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36 mm in the ipsilateral group, and from 8.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90 mm to 14.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64 mm in the contralateral group. Notably, the increase was more pronounced in the ipsilateral group, suggesting that selecting a door-opening side aligned with the larger ossification-occupied area is more favorable.\u003c/p\u003e\u003cp\u003eC5 nerve root palsy is a relatively common complication following posterior cervical surgery, with an incidence of 8.57% (3/35) in this study. Its pathogenesis may involve intraoperative nerve root traction, spinal cord migration, or impaired blood supply. Clinically, C5 nerve root palsy primarily presents as postoperative weakness of the deltoid and biceps brachii muscles, accompanied by dysfunction in shoulder abduction and elbow flexion [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In our study, the incidence of C5 nerve root palsy was 10% in the ipsilateral group and 6.67% in the contralateral group, with no statistically significant difference. Although rare, C5 nerve root palsy substantially impacts patients\u0026rsquo; quality of life. Thus, excessive nerve root traction should be avoided intraoperatively, and early postoperative detection\u0026mdash;combined with neurotrophic medication and rehabilitation training\u0026mdash;should be implemented when palsy occurs.\u003c/p\u003e\u003cp\u003eAxial symptoms are among the most prevalent complications after posterior cervical surgery, occurring in 17.14% (6/35) of patients in this study. These symptoms, characterized by neck and shoulder pain, stiffness, and limited range of motion, may result from extensive intraoperative dissection of paravertebral muscles, reduced cervical mobility, or facet joint injury [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The incidence of axial symptoms was 20% in the ipsilateral group and 13.33% in the contralateral group, with no statistically significant difference. While most axial symptoms are self-limiting, they significantly hinder postoperative recovery and reduce quality of life. To lower their incidence, surgeons should minimize the scope of muscle dissection intraoperatively, and patients should undergo early neck and shoulder functional exercises postoperatively.\u003c/p\u003e\u003cp\u003eCSF leakage is a serious spinal surgery complication; no cases were observed in this study. However, literature reports an incidence of 1%\u0026ndash;17% [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], primarily associated with dural injury or adhesion between ossification and the dura mater. CSF leakage can lead to postoperative complications such as headache and incisional infection. Therefore, careful dissection of ossification from the dura mater is essential intraoperatively. If dural injury is detected, immediate repair is required, with biological fibrin glue or fascia coverage used if necessary. Postoperative laminoplasty closure\u0026mdash;defined as failure to maintain the lamina in an open state after door-opening, leading to recurrent spinal canal stenosis\u0026mdash;was not observed in this study. However, literature cites an incidence of approximately 10% [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], which may result from hinge-side fractures, inadequate fixation, or excessive cervical movement postoperatively. To prevent this, surgeons should ensure appropriate width of the hinge-side bone groove, use reliable fixation techniques (e.g., mini-plates or anchors) to keep the lamina open, and advise patients to wear a cervical collar postoperatively to restrict cervical movement.\u003c/p\u003e\u003cp\u003eNo significant differences in postoperative complications\u0026mdash;including C5 nerve root palsy, axial symptoms, and transient deltoid pain\u0026mdash;were found between the two groups. This indicates that selecting a door-opening side aligned with the ossification-occupied area does not increase the risk of surgical complications. Kaneyama et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] reported a higher incidence of C5 nerve root palsy after single-door laminoplasty than double-door laminoplasty, potentially due to asymmetric spinal cord migration. In our study, however, the incidence of C5 nerve root palsy and axial symptoms did not differ significantly between the two groups. Notably, transient deltoid pain (innervated by the C5 nerve root) was more prominent in the ipsilateral group, likely due to more significant posterior spinal cord migration in this group. The ipsilateral group also had a slightly higher incidence of postoperative axial symptoms than the contralateral group (20% vs 13.33%). While this difference was not statistically significant, it merits attention in clinical practice. Given that axial symptoms may be linked to reduced postoperative cervical mobility, minimizing intraoperative damage to posterior cervical structures is recommended to lower their incidence.\u003c/p\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003eLimitations\u003c/h2\u003e\u003cp\u003eThis study has several limitations. First, the sample size was small; therefore, caution should be exercised when generalizing these findings to a larger population. Second, this retrospective study only included a small number of patients from a single institution, and further research with larger multi-center cohorts is needed. Third, we only selected patients treated by the same orthopedic surgeon to control the impact of surgical techniques on the results. Finally, the follow-up period of this study was relatively short.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe results of this study suggest that for patients with multi-segment asymmetric C-OPLL, the surgical strategy of selecting a door-opening side consistent with the side of the larger ossification-occupied area has advantages in improving neurological function, expanding the cervical spinal canal sagittal diameter, and delaying ossification progression. This finding provides an important basis for clinical surgical decision-making. However, the optimization of surgical strategies still needs to be combined with the specific conditions of patients, including the type and scope of ossification, and the degree of spinal cord compression.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cem\u003eEthics approval and consent to participate\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe Ethics Review Committee of the First Affiliated Hospital of Anhui University of Science and Technology; The First Affiliated Hospital of Anhui University of Technology\u003c/p\u003e\n\u003cp\u003eThe Ethics Review Committee of the First Affiliated Hospital of Anhui University of Science and Technology\u0026nbsp;approved the conduct of this study. All patients and their families gave written informed consent. The design of this study complies with the 1964 Helsinki Declaration and its subsequent amendments, as well as comparable ethical standards.\u003c/p\u003e\n\u003cp\u003eConsent for the publication of identifying images or other personal or clinical details of participants that compromise anonymity：Not Applicable\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eProject fund:\u003c/em\u003e Supported by “Research Funds of Joint Research Center for Occupational Medicine and Health of IHM”(NO.OMH-2023-28).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAll authors agree to submit this paper for publication.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAvailability of data and materials\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe data and materials that support the findings of this study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCompeting interests\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eChen Z, Liu B, Dong J, et al. Comparison of anterior corpectomy and fusion versus laminoplasty for the treatment of cervical ossification of posterior longitudinal ligament: a meta-analysis. Neurosurg Focus. 2016;40(6):E8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun N, Jiang C, Liu Y. Surgical options for ossification of the posterior longitudinal ligament of the cervical spine: a narrative review. J Orthop Surg Res. 2024;19(1):707.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQin R, Chen X, Zhou P, Li M, Hao J, Zhang F. Anterior cervical corpectomy and fusion versus posterior laminoplasty for the treatment of oppressive myelopathy owing to cervical ossification of posterior longitudinal ligament: a meta-analysis. Eur Spine J. 2018;27(6):1375\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQin R, Chen X, Zhou P, Li M, Hao J, Zhang F. Anterior cervical corpectomy and fusion versus posterior laminoplasty for the treatment of oppressive myelopathy owing to cervical ossification of posterior longitudinal ligament: a meta-analysis. Eur Spine J. 2018;27(6):1375\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXu P, Zhuang JS, Huang YS, Tu C, Chen JT, Zhong ZM. Surgical outcomes of cervical myelopathy due to ossification of posterior longitudinal ligament: Anterior decompression and fusion versus posterior laminoplasty. J Orthop Surg (Hong Kong). 2019;27(2):2309499019837907.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang J, Liang Q, Qin D, et al. The anterior versus posterior approach for the treatment of ossification of the posterior longitudinal ligament in the cervical spine: A systematic review and meta-analysis. J Spinal Cord Med. 2021;44(3):340\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHirabayashi K, Toyama Y, Chiba K. Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament. Clin Orthop Relat Res. 1999;(359):35\u0026ndash;48.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHou Y, Liang L, Shi GD, Xu P, Xu GH, Shi JG, Yuan W. Comparing effects of cervical anterior approach and laminoplasty in surgical management of cervical ossification of posterior longitudinal ligament by a prospective nonrandomized controlled study. Orthop Traumatol Surg Res. 2017;103(5):733\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang Q, Guo R, Fang S, Tong S, Fan Y, Wang J. The clinical efficacy of laminectomy fusion fixation and posterior single open-door laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL): a retrospective study. BMC Surg. 2023;23(1):380.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBasu S, Gohil K. Comparing Spinal Cord Drift, Clinical Outcomes and C5 Palsy in Degenerative Cervical Myelopathy: A Study of Cervical Laminoplasty Versus Laminectomy/Fusion. Global Spine J. 2025;15(2):1277\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSodeyama T, Goto S, Mochizuki M, Takahashi J, Moriya H. Effect of decompression enlargement laminoplasty for posterior shifting of the spinal cord. Spine (Phila Pa 1976). 1999;24(15):1527\u0026ndash;31. discussion 1531-2.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKang MS, Kim KH, Park JY, Kuh SU, Chin DK, Kim KS, Jin BH, Cho YE. Progression of Cervical Ossification of Posterior Longitudinal Ligament After Laminoplasty or Laminectomy With Posterior Fixation. Clin Spine Surg. 2019;32(9):363\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang L, Jiang Y, Li M, Qi L. Postoperative Progression of Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review. World Neurosurg. 2019;126:593\u0026ndash;600.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee JJ, Shin DA, Yi S, Kim KN, Yoon DH, Shin HC, Ha Y. Effect of posterior instrumented fusion on three-dimensional volumetric growth of cervical ossification of the posterior longitudinal ligament: a multiple regression analysis. Spine J. 2018;18(10):1779\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eXu C, Zhang Y, Dong M, Wu H, Yu W, Tian Y, Cao P, Chen H, Wang X, Shen X, Liu Y, Yuan W. The relationship between preoperative cervical sagittal balance and clinical outcome of laminoplasty treated cervical ossification of the posterior longitudinal ligament patients. Spine J. 2020;20(9):1422\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCha JR, Kim HW, Yang DG, Chung HY, Hwang IY. Open-Door Laminoplasty Using Lateral Mass Anchoring Screws and Nonabsorbable Sutures in Patients with Multilevel Cervical Myelopathy. Clin Orthop Surg. 2020;12(4):477\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhuyagbaatar B, Kim K, Purevsuren T, Lee SH, Kim YH. Biomechanical Effects on Cervical Spinal Cord and Nerve Root Following Laminoplasty for Ossification of the Posterior Longitudinal Ligament in the Cervical Spine: A Comparison Between Open-Door and Double-Door Laminoplasty Using Finite Element Analysis. J Biomech Eng. 2018;140(7). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1115/1.4039826\u003c/span\u003e\u003cspan address=\"10.1115/1.4039826\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhuyagbaatar B, Kim K, Park WM, Kim YH. Biomechanical investigation of post-operative C5 palsy due to ossification of the posterior longitudinal ligament in different types of cervical spinal alignment. J Biomech. 2017;57:54\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee SE, Chung CK, Jahng TA, Kim HJ. Long-term outcome of laminectomy for cervical ossification of the posterior longitudinal ligament. J Neurosurg Spine. 2013;18(5):465\u0026ndash;71.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStr\u0026ouml;mqvist F, J\u0026ouml;nsson B, Str\u0026ouml;mqvist B. Swedish Society of Spinal Surgeons. Dural lesions in lumbar disc herniation surgery: incidence, risk factors, and outcome. Eur Spine J. 2010;19(3):439\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAmoozegar F. Spinal Cerebrospinal Fluid Leaks/Intracranial Hypotension. Neurosurg Clin N Am. 2025;36(2):299\u0026ndash;309.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen G, Luo Z, Nalajala B, Liu T, Yang H. Expansive open-door laminoplasty with titanium miniplate versus sutures. Orthopedics. 2012;35(4):e543\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKaneyama S, Sumi M, Kanatani T, Kasahara K, Kanemura A, Takabatake M, Nakatani T, Yano T. Prospective study and multivariate analysis of the incidence of C5 palsy after cervical laminoplasty. Spine (Phila Pa 1976). 2010;35(26):E1553\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of Baseline Characteristics Between Groups\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSex (male: female)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eBMI (kg/m2)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOperative time (min)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIntraoperative blood loss (ml)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eContralateral group (N\u0026thinsp;=\u0026thinsp;15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e59.53\u0026thinsp;\u0026plusmn;\u0026thinsp;6.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9 (60) : 6 (40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e129.33\u0026thinsp;\u0026plusmn;\u0026thinsp;9.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e150.67\u0026thinsp;\u0026plusmn;\u0026thinsp;11.32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConcordant group (N\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60.20\u0026thinsp;\u0026plusmn;\u0026thinsp;9.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13 (65) : 7 (35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.6.00\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e129.5.00\u0026thinsp;\u0026plusmn;\u0026thinsp;10.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e151.00\u0026thinsp;\u0026plusmn;\u0026thinsp;13.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et/\u0026chi;2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.245\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.589\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.048\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.080\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.808\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.962\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.937\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003cp\u003eTable\u0026nbsp;2. Comparison of Clinical Outcomes Between Groups\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Taba\" border=\"1\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eContralateral\u003c/p\u003e\n \u003cp\u003egroup (N\u0026thinsp;=\u0026thinsp;15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConcordant group (N\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" align=\"left\"\u003e\n \u003cp\u003eVAS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.60\u0026thinsp;\u0026plusmn;\u0026thinsp;1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.187\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.853\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.774\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.223\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.203\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" align=\"left\"\u003e\n \u003cp\u003eJOA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.00\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.80\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.378\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.708\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.795\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-6.902\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-8.311\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" align=\"left\"\u003e\n \u003cp\u003eNDI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.20\u0026thinsp;\u0026plusmn;\u0026thinsp;3.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.141\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.889\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.33\u0026thinsp;\u0026plusmn;\u0026thinsp;2.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.30\u0026thinsp;\u0026plusmn;\u0026thinsp;2.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.047\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.963\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.337\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.892\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable\u0026nbsp;3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of Radiographic Outcomes Between Groups\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eContralateral\u003c/p\u003e\n \u003cp\u003egroup (N\u0026thinsp;=\u0026thinsp;15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConcordant group (N\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" align=\"left\"\u003e\n \u003cp\u003eC2-7 Cobb angle (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.84\u0026thinsp;\u0026plusmn;\u0026thinsp;2.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.82\u0026thinsp;\u0026plusmn;\u0026thinsp;4.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.987\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.96\u0026thinsp;\u0026plusmn;\u0026thinsp;2.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.774\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.431\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.898\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"4\" align=\"left\"\u003e\n \u003cp\u003eSpinal canal sagittal diameter (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.911\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.795\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-20.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-20.608\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"5\" align=\"left\"\u003e\n \u003cp\u003eC2-7SVA\u003c/p\u003e\n \u003cp\u003e(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePreoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.300\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.766\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1-Year Postoperative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.234\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.817\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.337\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.892\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eChange in C2-7 SVA (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.991\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable\u0026nbsp;4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003e\u003cstrong\u003eComparison of Ossification Characteristics Between Groups\u003c/strong\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eChange in ossification longitudinal length (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eChange in ossification thickness (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eContralateral group (N\u0026thinsp;=\u0026thinsp;15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConcordant group\u003c/p\u003e\n \u003cp\u003e(N\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003et\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.526\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.146\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.040\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003cstrong\u003eTable 5. Comparison of postoperative adverse events between groups\u003c/strong\u003e\u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"char\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tabb\" border=\"1\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTransient pain in the deltoid region\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eC5 nerve root palsy\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAxial symptoms\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal complication rate\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eContralateral group (N\u0026thinsp;=\u0026thinsp;15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3 (20.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1 (6.67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2 (13.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6 (13.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eConcordant group (N\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9 (45.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2 (10.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4 (20.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15 (25.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026chi;2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.188\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.808\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.560\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.139\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\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":"C-OPLL, Posterior open-door laminoplasty, C2-C7 Cobb angle, C2-7 SVA","lastPublishedDoi":"10.21203/rs.3.rs-7663372/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7663372/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThis study investigates the impact of the choice of door-opening side on neurological recovery, radiographic decompression adequacy, and complications in patients with asymmetric ossification of the posterior longitudinal ligament (OPLL), so as to provide evidence-based guidance for the selection of surgical side .\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eA retrospective analysis was performed on the data of 35 patients with asymmetric C-OPLL who underwent cervical posterior single-door laminoplasty (CPSDL) from September 2020 to January 2024. Patients were divided into two groups: the ipsilateral group, when the door-opening side was consistent with the predominant OPLL occupation side, and the contralateral group, when the door-opening side was inconsistent with the predominant OPLL occupation. The following parameters were evaluated: Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) for pain, C2\u0026ndash;7 Cobb angle, sagittal diameter of the cervical canal, C2\u0026ndash;7 sagittal vertical axis (SVA), axial length and thickness of ossified lesions. Clinical outcomes were compared between the two groups to comprehensively evaluate the impact of the choice of door-opening sidein asymmetric OPLL.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThere were no significant differences between the two groups in postoperative Neck Disability Index (NDI) score, C2-7 SVA, incidence of C5 nerve root palsy, and axial symptoms, and total incidence of complications. The ipsilateral group had more significant improvements in C2-7 Cobb angle, sagittal diameter of cervical spinal canal, VAS, and JOA score.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eFor patients with asymmetric C-OPLL, the predominant OPLL occupation side is preferred as the door-opening side in CPSDL\u003c/p\u003e","manuscriptTitle":"Impact of Door-Opening Side Selection on Surgical Outcomes in single-door cervical laminoplasty for Asymmetric Ossification of the Posterior Longitudinal Ligament","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-13 08:01:19","doi":"10.21203/rs.3.rs-7663372/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":"4eb2f910-1bc4-4790-bcb9-0b556bd505e6","owner":[],"postedDate":"November 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-19T08:44:41+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-13 08:01:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7663372","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7663372","identity":"rs-7663372","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}