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Dysphagia is one of the postoperative complications of cervical degenerative disorders. However, few studies have evaluated the pre- and postoperative swallowing function in detail.To analyze pre- and postoperative swallowing dynamics kinetically and investigate factors associated with postoperative dysphagia in patients with cervical degenerative disorders.Retrospective review of prospectively collected data.A total of 41 consecutive patients who underwent an anterior approach (anterior cervical discectomy/corpectomy and fusion (ACDF, ACCF), hybrid surgery (ACDF+ACCF) and total disc replacement) and 44 consecutive patients who underwent a posterior approach (laminoplasty and laminoplasty/laminectomy with fusion).We compared the pre- and postoperative functional oral intake scale (FOIS), dysphagia severity scale (DSS), esophageal dysphagia, anterior/superior hyoid movement, upper esophageal sphincter (UES) opening, pharyngeal transit time, bolus residue scale (BRS), and the number of swallows.Videofluoroscopy was performed on the day before surgery and within two weeks after surgery. Data related to age, gender, disease, surgical procedure, surgical site, operative time, and blood loss were collected from the medical records. Pre- and postoperative data were compared for each item in the anterior and posterior approaches. The odds ratio of dysphagia after an anterior approach was also calculated.In the anterior approach, DSS, FOIS, the anterior and superior hyoid movements, maximum UES opening, BRS, and number of swallows worsened postoperatively (p.05, respectively). In the posterior approach, DSS, FOIS, the anterior hyoid movement, and BRS worsened postoperatively (p.05, respectively). The factors associated with dysphagia were a proximal surgical site above C3 (OR: 14.40, CI: 2.84-73.02), blood loss100 ml (OR: 9.60, CI: 2.06-44.74), an operative time200 min (OR: 8.18, CI: 1.51-44.49), and an extensive surgical field of more than three intervertebral levels (OR: 6.72, CI: 1.50-30.07). The decline in swallowing function after the posterior approach was related to aging (p = .045).Each approach may decrease swallowing function, especially because of the limitation on the anterior hyoid movement. Dysphagia after anterior approaches was associated with the operative site, operative time, and blood loss.

Factors related to postoperative mechanical failure after long fusion with lower instrumented vertebra (LIV) at L5 have not been well investigated. Elucidating such factors may allow us to perform alternatives to spinopelvic fusion for adult spinal deformity (ASD) cases. We investigated the incidence and risk factors of LIV failure in patients with ASD who underwent surgical treatment of long corrective fusion until the L5 vertebrae.Between 2009 and 2018, 52 patients who underwent corrective fusions to L5 were followed-up for at least one-year. We evaluated the associated patient factors for LIV failure which include loosening of the pedicle screw of LIV, fracture of LIV, distal junctional kyphosis (DJK).The mean age of the participants was 71.2 ± 7.59 (range, 44-84). LIV failure occurred in 20 patients (38.5%), and 6 patients (11.5%) underwent secondary surgery for caudal segments. The mean pelvic incidence (PI) was 52.5 ± 9.8 in the failure group versus 45.3 ± 11.4 in non-failure group (P = 0.02) and pelvic tilt (PT) was 39.1 ± 9.0 versus 32.4 ± 13.0. There were no significant differences in sex, age, body mass index, number of levels fused, and other radiographic data. Logistic regression analysis that included T1 pelvic angle, PT, PI - postoperative LL and PI also identified PI as the only significant determinant of LIV failure (OR = 1.07, P = 0.034). Receiver operating characteristic analysis demonstrated that a PI over 50.0° was associated with LIV failure (sensitivity 63%, specificity 70%, AUC 0.694).LIV failure was frequently observed after long corrective fusion for patients with ASD. High PI was found to be a significant risk factor for the LIV failure.

Few studies have directly compared anterior and posterior surgical approaches in cervical spondylotic myelopathy (CSM) patients with short-segment disease. We aimed to examine and compare surgical outcomes of anterior cervical discectomy with fusion (ACDF) and selective laminoplasty (S-LAMP) in CSM patients with 1- or 2-level disease.Forty-six patients, who received surgeries for CSM, were prospectively investigated; 24 underwent ACDF and 22 underwent S-LAMP. Average follow-up was 3.5 years. The following pre- and postoperative radiographic measurements were recorded: (1) C2-7 angle, (2) local angle (lordotic Cobb angle at operative level), (3) cervical sagittal vertical axis (SVA) (center of gravity of the head-C7 SVA), and (4) C7 slope. Outcomes were evaluated using the Japanese Orthopedic Association scoring system for cervical myelopathy (C-JOA score), neck pain visual analog scale, and neck disability index (NDI).There were no significant differences in patient demographics between the two groups. Postoperatively, C2-7 angle, local angle, cervical SVA, C7 slope, C-JOA score, and neck pain and NDI scores were not significantly different between the two groups; however, the recovery rate of the C-JOA score was superior in the ACDF group (57.5%) compared to the S-LAMP group (42.1%). The recovery rate of the C-JOA score in the local lordosis subgroup (local angle ≥ 0°) showed no significant difference between the two surgical groups. However, in the local kyphosis subgroup (local angle 0°), C-JOA score recovery rate was worse after S-LAMP (20.4%) than ACDF (57.9%); local angle also worsened postoperatively after S-LAMP.In patients with local lordosis at the segments of cervical spondylosis and spinal cord compression, S-LAMP showed equivalent surgical outcomes (neurological recovery, neck pain and NDI scores, and cervical alignment) to ACDF. However, in patients with local kyphosis, S-LAMP worsened the kyphosis and resulted in worse neurological recovery.

Background Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by heterotopic bone formation in the posterior longitudinal ligament of the spine. Although the patients with OPLL are more common in the 60s and 70s, we know that there are markedly young patients (e.g., early 40s). However, to the best of our knowledge, there is few reports characterize young patients with cervical OPLL in terms of the imaging features, subjective symptoms, and ADL problems. Methods This is the multicenter cross-sectional study. Two hundred and thirty-seven Japanese symptomatic patients with cervical OPLL confirmed by standard X-rays collected from 16 institutions belonging to the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament formed by the Japanese Ministry of Health, Labor and Welfare were recruited. Whole spine CT data as well as demographic data such as age, gender, patients-based evaluations, and the 36-item Short Form Health Survey (SF-36) were evaluated. Results Young group (≦ 45 years old) consisted of 23 patients (8 females and 15 males), accounting for 9.7% of the total. Their characteristics were high body mass index (BMI), significant involvement of trauma in the onset and deterioration of symptoms, and the predominance of thoracic OPLL. The patient-based evaluations did not show a significant difference between the young and non-young groups, or between the genders in the young group except for bodily pain (BP) of SF-36. Female patients in young group had significantly lower BP score of SF-36 than that of male in young group. Conclusions Characteristics of young patients with cervical OPLL were high BMI, significant involvement of trauma in the onset and deterioration of symptoms, lower BP score of SF-36 in female, and the predominance of thoracic OPLL.

Its rare prevalence and subtle radiological changes often lead to difficulties in diagnosing cervical ossification of the posterior longitudinal ligament (OPLL) on plain radiographs. However, OPLL progression may lead to trauma-induced spinal cord injury, resulting in severe paralysis. To address the difficulties in diagnosis, a deep learning approach using a convolutional neural network (CNN) was applied.The aim of our research was to evaluate the performance of a CNN model for diagnosing cervical OPLL.Diagnostic image study.This study included 50 patients with cervical OPLL, and 50 control patients with plain radiographs.For the CNN model performance evaluation, we calculated the area under the receiver operating characteristic curve (AUC). We also compared the sensitivity, specificity, and accuracy of the diagnosis by the CNN with those of general orthopedic surgeons and spine specialists.Computed tomography was used as the gold standard for diagnosis. Radiographs of the cervical spine in neutral, flexion, and extension positions were used for training and validation of the CNN model. We used the deep learning PyTorch framework to construct the CNN architecture.The accuracy of the CNN model was 90% (18/20), with a sensitivity and specificity of 80% and 100%, respectively. In contrast, the mean accuracy of orthopedic surgeons was 70%, with a sensitivity and specificity of 73% (SD: 0.12) and 67% (SD: 0.17), respectively. The mean accuracy of the spine surgeons was 75%, with a sensitivity and specificity of 80% (SD: 0.08) and 70% (SD: 0.08), respectively. The AUC of the CNN model based on the radiographs was 0.924.The CNN model had successful diagnostic accuracy and sufficient specificity in the diagnosis of OPLL.

Lumbar canal stenosis due to degenerative lumbar spondylolisthesis is one of the most common indications for lumbar spinal surgery. However, from a long-term perspective, it is still unclear which of these procedures should be performed: decompression, decompression plus fusion, or decompression plus stabilization.This study aimed to present the long-term results of a randomized controlled trial of surgery for degenerative spondylolisthesis.This is a long-term follow-up of a previously reported randomized controlled trial.Patients aged ≤75 years with single L4/5 level lumbar canal stenosis caused by degenerative lumbar spondylolisthesis were enrolled at two hospitals from May 1, 2003, to April 30, 2012; the final follow-up was on May 20, 2021.The following data were collected: modified Japanese Orthopedic Association (JOA) score, visual analog scale (VAS) score for lower back pain, leg pain, and numbness, and scores from eight Short-Form 36 (SF-36) subscales preoperatively, 1 year postoperatively, 5 years postoperatively, and at the final follow-up.Patients were randomized to undergo decompression alone, decompression plus fusion, or decompression plus stabilization. The primary outcome measure was the change in VAS for lower back pain with secondary outcomes including the modified JOA score, VAS for leg pain, VAS for leg numbness, eight SF-36 subscale scores, and occurrence of reoperation at the last follow-up.Among 85 patients who were randomized, 66 responded to the current survey. The mean follow-up period was 12.3 years. The VAS score for low back pain improvement was not significantly different between the decompression and fusion groups at the mean follow-up of 12.3 years. Of the 12 secondary outcomes, 8 showed no significant difference between decompression and fusion, 12 showed no significant difference between decompression and stabilization, and 10 showed no significant difference between fusion and stabilization.Although additional instrumentation surgery did not significantly improve low back pain at the mean follow-up of 12.3 years compared with decompression alone, fusion surgery provided clinically meaningful improvements in patient-reported vitality, social functioning, role limitations due to personal or emotional problems, and mental health compared with decompression alone.UMIN000028114.

Thoracic ossification of the posterior longitudinal ligament (T-OPLL) is a rare disease, which can cause spinal cord compression leading to various neurological symptoms. There are limited treatment options for T-OPLL, surgery is generally considered the only effective treatment. However, few studies have investigated surgical complications in patients with T-OPLL, and there are no data regarding surgical risks in anterior decompression with fusion (ADF) when compared with posterior decompression with fusion (PDF) for T-OPLL.Patients who were diagnosed as T-OPLL and underwent ADF via the anterior approach and PDF via the posterior approach from April 1, 2012 to March 31, 2018, were extracted from the Diagnosis Procedure Combination (DPC) database. We analyzed perioperative systemic and local complication rates after ADF and PDF and compared them using propensity score matching (PSM) method. In each of the two groups, we investigated the details of length of stay, costs, mortality, and discharge destination.In total 1344 patients (ADF: 88 patients, PDF: 1256 patients), 176 patients were investigated after PSM (88 pairs). While the incidence of overall systemic complication was significantly higher in the ADF group (ADF/PDF: 25.0%/8.0%, P = 0.002), there was no significant difference in the overall local complication rate (15.9%/19.3%, P = 0.55). Specifically, respiratory complications were more frequently observed in the ADF group (9.1%/0%, P = 0.004), however, other systemic and local complications did not differ significantly between the two groups. The length of stay was 1.7 times longer (P 0.001) and the medical costs were 1.4 times higher (P 0.001) in patients with perioperative complications, compared to those without perioperative complications.We demonstrated the perioperative complications of ADF and PDF in patients with T-OPLL using a large national database. ADF showed a higher incidence of respiratory complications. Development of perioperative complications was associated with longer hospital stay and higher medical costs.

Background Autologous bone has been used for posterior lumbar intervertebral fusion (PLIF). However, harvesting autologous bone graft is associated with donor site complications. We previously developed a hydroxyapatite/collagen (HAp/Col) composite as an osteoconductive artificial bone, characterized by having a highly porous structure with sponge‐like elasticity. This study aims to investigate the effectiveness of HAp/Col composite with bone marrow aspirate (BMA) as a graft substitute in PLIF for the treatment of lumbar spinal diseases. Methods This study prospectively investigated patients who received one-level PLIF. For the interbody fusion, two titanium cages were inserted. On the one side of interbody space, HAp/Col composite incorporated with BMA filling the titanium cage was grafted. On the other side, local bone graft (LBG) harvested during decompressive laminotomy was grafted and then one-level instrumentation using pedicle screws was performed. The target levels were at L2/3 in 2 cases, L3/4 in 3 cases, L4/5 in 36 cases, and L5/S in 5 cases. We evaluated clinical symptoms and radiological outcomes of 46 patients and compared the fusion status of HAp/Col composite with that of LBG. Results The 1-year postoperative CT evaluation demonstrated that, in the HAp/Col, a complete fusion was observed in 38 patients (82.6%), whereas in the LBG, a complete fusion was observed in 35 patients (76.1%). There were no statistical differences between the HAp/Col and LBG. In the HAp/Col, incomplete fusion was observed in five patients (10.9%) and non-fusion in two patients (4.3%), and in the LBG, incomplete fusion was observed in nine patients (19.6%) and non-fusion in two patients (4.3%). At 2 years after the surgery, complete fusion increased to 44 patients (95.7%) in the HAp/Col and 41 patients (89.1%) in the LBG. There were no significant differences in the clinical scores for lumbar spine between patients with fusion and non-fusion. Conclusions The HAp/Col composite with BMA in the titanium cage can be effectively used as an alternative to conventional autologous LBG for intervertebral spinal fusion. Trial registration University hospital Medical Information Network, UMIN000045010, July 30th, 2021, Retrospectively registered, https://www.umin.ac.jp/english/.

Background Patients with prolonged and intense neutrophilia after spinal surgery are at high risk of developing surgical site infection (SSI). To date, there is no standard method for the objective assessment of the intensity and duration of neutrophilia. Thus, this retrospective observational study aimed to test a new index (I-index), developed by combining the duration and intensity of neutrophilia, as a predictor of SSI. Methods I-index was calculated based on the postoperative neutrophil percentage. A total of 17 patients with SSI were enrolled as cases, and 51 patients without SSI were selected as controls. The groups were matched at a ratio of 1:3 by age, sex, and surgery type. The differences in the I-index were compared between the groups. Moreover, we checked the cumulative I-index (c-I-index), which we defined as the area under the neutrophil curve from postoperative day 1 until the first clinical manifestation of SSI in each case. Furthermore, a cutoff for SSI was defined using the receiver operating characteristic curve. Results The median I-index-7, I-index-14, and c-I-index were significantly higher in the SSI group than those in the control group. For a cutoff point of 42.1 of the I-index-7, the sensitivity and specificity were 0.706 and 0.882, respectively. For a cutoff point of 45.95 of the I-index-14, the sensitivity and specificity were 0.824 and 0.804, respectively. For a cutoff point of 45.95 of the c-I-index, the sensitivity and specificity were 0.824 and 0.804, respectively. Conclusion We devised a new indicator of infection, i.e., the I-Index and c-I-index, and confirmed its usefulness in predicting SSI.

Study design This was a prospective multicenter study. Objective The aim of this study was to investigate the perioperative complications of posterior surgeries for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL). Summary of background data Surgical treatment for cervical OPLL has a high risk of various complications. Laminoplasty (LAMP) and posterior decompression and instrumented fusion (PDF) are effective for multilevel cervical OPLL; however, few studies have focused on the surgical complications of these 2 procedures. Materials and methods We prospectively included 380 patients undergoing posterior surgeries for cervical OPLL (LAMP: 270 patients, PDF: 110 patients), and investigated the systemic and local complications, including neurological complications. We further evaluated risk factors related to the neurological complications. Results Motor palsy was found in 40 patients (10.5%), and motor palsy in the upper extremity was most frequent (8.9%), especially in patients who received PDF (14.5%). Motor palsies involving the lower extremities was found in 6 patients (1.6%). Regarding local complications, dural tears (3.9%) and surgical site infections (2.6%) were common. In the univariate analysis, body mass index, preoperative cervical alignment, fusion surgery, and the number of operated segments were the factors related to motor palsy. Multivariate analysis revealed that fusion surgery and a small preoperative C2-C7 angle were the independent factors related to motor palsy. Motor palsy involving the lower extremities tended to be found at early time points after the surgery, and all the patients fully recovered. Motor palsy in the upper extremities occurred in a delayed manner, and 68.8% of patients with PDF showed good recovery, whereas 81.3% of patients with LAMP showed good recovery. Conclusions In posterior surgeries for cervical OPLL, segmental motor palsy in the upper extremity was most frequently observed, especially in patients who received PDF. Fusion and a small preoperative C2-C7 angle were the independent risk factors for motor palsy. Level of evidence Level III.

Although osteoporotic vertebral fractures (OVFs) are the most common type of osteoporotic fracture, few reports have closely investigated the factors contributing to the quality of life (QOL) in the chronic phase after thoracolumbar OVFs using detailed radiographic evaluation.This study aimed to identify factors associated with the QOL in the chronic phase after thoracolumbar OVF.Post-hoc analysis of a prospective randomized study.Participants included 195 patients with fresh thoracolumbar OVF managed conservatively with a brace who were available for radiographic analysis 48 weeks after injury.The degree of QOL impairment at 48 weeks after thoracolumbar OVF was assessed using the Japanese three-level version of the EuroQol five-dimensional questionnaire (EQ-5D) score.Univariate and multivariate regression analyses were used to evaluate the relationships between the QOL and radiographic factors.The univariate analysis showed that age, analgesic use, T10/L5 Cobb angle on magnetic resonance imaging (MRI), subsequent vertebral fracture, and nonunion were significantly associated with the EQ-5D score at 48 weeks after thoracolumbar OVF. The multiple regression analysis showed that nonunion, analgesic use, subsequent vertebral fracture, and sacral slope on MRI were independently associated with the EQ-5D score at 48 weeks after thoracolumbar OVF. Receiver operating characteristic analysis for the deterioration of QOL showed that the cutoff value for sacral slope on MRI was 35 degrees.This study demonstrated that nonunion, subsequent vertebral fracture, and lower sacral slope were independently associated with poorer QOL in the chronic phase of thoracolumbar OVF managed conservatively with a brace. Therefore, improving or preventing these factors in patients with thoracolumbar OVF in the chronic phase may improve the QOL of the affected patients.

Although favourable surgical outcomes for myelopathy caused by cervical ossification of the posterior longitudinal ligament (OPLL) have been reported, factors significantly associated with post-operative neck pain attenuation still remain unclear. The primary aim of the present study was to determine factors significantly associated with post-operative neck pain attenuation in patients with cervical OPLL using a prospective multi-centre registry of surgically treated cervical OPLL. Significant postoperative neck pain reduction (50% reduction of neck pain) was achieved in 31.3% of patients. There was no significant difference in neck pain attenuation between surgical procedures. Statistical analyses with univariate analyses followed by stepwise logistic regression revealed neurological recovery as a factor having a significant positive association with post-operative neck pain attenuation (p = 0.04, odds ratio 5.68 (95% confidence interval: 1.27–22.2)). In conclusion, neurological recovery was an independent factor having a significant positive association with post-operative neck pain attenuation in patients with cervical myelopathy caused by OPLL who underwent cervical spine surgery.

STUDY DESIGN A retrospective cohort study with a national inpatient database. OBJECTIVE This study aimed to research the perioperative complication rates of cervical spondylotic myelopathy (CSM) patients who underwent anterior decompression with fusion (ADF) and posterior decompression with fusion (PDF) using a large national inpatient database and propensity score matching (PSM) analysis. SUMMARY OF BACKGROUND DATA There are several ways to successfully achieve surgical spinal decompression in CSM patients; however, evidence of the systemic complications and reoperation rates in ADF and PDF is lacking. MATERIALS AND METHODS We identified patients who were hospitalized for CSM and underwent either ADF or PDF from 2010 to 2016 using the Japanese Diagnosis Procedure Combination database. In the ADF and PDF groups, we compared postoperative complications (systemic and local), medical costs during hospitalization, and mortality before and after PSM. In addition, multivariate regression analysis was performed to identify risk factors for perioperative systemic complications. RESULTS A total of 1013 matched pairs were made after PSM. More perioperative systemic complications were detected in the ADF group than in the PDF group (at least 1 complication: ADF vs. PDF: 15.2% vs. 12.0%, P=0.038), especially for respiratory failure (1.4% vs. 0.4%, P=0.018), pneumonia (1.9% vs. 0.5%, P=0.004), and dysphagia (3.0% vs. 1.1%, P=0.003). The costs were ~$8000 higher (P

Study design A retrospective analysis of prospectively collected data. Objective This study aimed to create a prognostic model for surgical outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) using machine learning (ML). Summary of background data Determining surgical outcomes helps surgeons provide prognostic information to patients and manage their expectations. ML is a mathematical model that finds patterns from a large sample of data and makes predictions outperforming traditional statistical methods. Methods Out of 478 patients, 397 and 370 patients had complete follow-up information at 1 and 2 year respectively and were included in the analysis. A minimal clinically important difference (MCID) was defined as an acquired Japanese Orthopaedic Association (JOA) score of 2.5 points or more, after which a ML model that predicts whether MCID can be achieved 1 and 2 years after surgery was created. Patient background, clinical symptoms, and imaging findings were used as variables for analysis. The ML model was created using LightGBM, XGBoost, random forest, and logistic regression, after which the accuracy and area under the receiver operating characteristic curve (AUC) were calculated. Results The mean JOA score was 10.3 preoperatively, 13.4 at 1 year after surgery, and 13.5 at 2 years after surgery. XGBoost showed the highest AUC (0.72) and high accuracy (67.8) for predicting MCID at 1 year, while random forest had the highest AUC (0.75) and accuracy (69.6) for predicting MCID at 2 years. Among the included features, total preoperative JOA score, duration of symptoms, body weight, sensory function of the lower extremity sub-score of the JOA, and age were identified as having the most significance in most of ML models. Conclusion Constructing a prognostic ML model for surgical outcomes in patients with OPLL is feasible, suggesting the potential application of ML for predictive models of spinal surgery.Level of Evidence: 4.

STUDY DESIGN A prospective multicenter study. OBJECTIVE To evaluate and compare the surgical outcomes after open-door (OD) and double-door (DD) laminoplasties in subjects with cervical ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA Although previous studies compared clinical results after OD and DD laminoplasties, they were performed at a single institution with a relatively small sample size targeting mixed pathologies, including cervical spondylotic myelopathy. METHODS This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of these, 41 and 164 patients received OD and DD laminoplasties, respectively. Demographic information, medical history, and imaging findings were collected. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire, and visual analog scale scores. RESULTS Age, sex, symptom duration, and comorbidities were not significantly different between the groups. Segmental ossification was the most frequent in both the groups. No significant differences in K-line type, canal occupying ratio, C2 to C7 angles, and range of motion were found. Both the procedures reduced the cervical range of motion postoperatively. A comparable frequency of perioperative complications was observed between the groups. The cervical Japanese Orthopaedic Association scores showed a similar improvement at 2 years postopera- tively. The reduction in visual analog scale score for neck pain was favorable in the OD group (P = 0.02), while other pain assessments did not show any significant differences between the groups. The functional outcomes assessed using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire presented equivalent effective rates. CONCLUSION The results demonstrated almost comparable surgical outcomes between OD and DD laminoplasties. Lamino- plasty is a valuable technique as a therapeutic option for cervical OPLL.Level of Evidence: 2.

Study design Prospective, nationwide case series. Objective To identify preoperative factors associated with myelopathy and neurological impairment in patients with cervical ossification of the posterior longitudinal ligament (OPLL). Summary of background data Various studies have reported clinical outcomes following the surgical treatment of OPLL. However, there has been no large-scale study of preoperative clinical features in patients with cervical OPLL. Materials and methods Data were prospectively collected from 28 institutions nationwide in Japan. In total, 512 patients with neurological impairment caused by cervical OPLL requiring surgery were enrolled. Basic demographic and clinical data, including age, sex, diabetes status, body mass index, smoking history, and disease duration were collected. C2-7 lordotic angle, canal narrowing ratio, range of motion in flexion-extension at C2-7, and type of OPLL were evaluated on lateral radiographs to identify factors influencing the clinical features of patients with OPLL in whom surgery was planned. Results Complete documentation was available for 490 patients (362 male, 128 female). In total, 34 patients had the localized type, 181 had the segmental type, 64 had the continuous type, and 211 had the mixed type. Although there were no significant differences in age, body mass index, disease duration, Japanese Orthopedic Association (JOA) score, and lordotic angle at C2-7 according to the type of OPLL, significant differences were observed in a range of motion at C2-7 and the canal narrowing ratio among the 4 types. Multiple regression analysis revealed that the JOA score was significantly associated with age and signal intensity change on magnetic resonance imaging. Conclusions This is the first large-scale, prospective, multicenter case series study to investigate factors influencing preoperative neurological status in patients with OPLL. Age and signal intensity change on magnetic resonance images were significantly associated with JOA score in patients requiring surgery. Level of evidence Level II.

Background No studies to date have elucidated the clinical factors associated with pedicle screw pull-out during or immediately after surgery. The aim of this study was to assess the frequency of pedicle screw pull-out by comparing intraoperative scans obtained using cone-beam computed tomography (CBCT) with postoperative scans obtained using computed tomography (CT). We also sought to determine the incidence of pedicle screw pull-out and identify relevant risk factors. Methods This was a retrospective analysis of prospectively collected data for 742 pedicle screws placed in 76 consecutive patients who underwent at least triple-level posterior fixation for thoracic or lumbar spinal injury, spinal metastasis, or pyogenic spondylitis between April 2014 and July 2020. Pedicle screw pull-out distance in the axial and sagittal planes was compared between CT scans obtained 2 days postoperatively and CBCT images acquired intraoperatively. Risk factors associated with pedicle screw pull-out were investigated by multivariate logistic regression analysis. Results Pedicle screw pull-out was seen with 58 pedicle screws (7.8%) in 26 patients (34.2%). There were significant differences in age, number of fused segments, frequency of diffuse idiopathic skeletal hyperostosis (DISH), and medical history of osteoporosis for pedicle screw pull-out. Risk factors for pedicle screw pull-out were older age (odds ratio 1.07, 95% confidence interval 1.02–1.130) and a diagnosis of DISH (odds ratio 3.35, 95% confidence interval 1.12–10.00). Several cases suggest that use of connecting rods was an important factor in intraoperative pedicle screw pull-out. Conclusions Our findings suggest that age, number of fused segments, presence of DISH, and medical history of osteoporosis are risk factors for pedicle screw pull-out, with the greatest being older age and DISH.

Purpose Although the understanding of the mechanisms of low back pain due to spinopelvic sagittal imbalance has strengthened, the understanding of the mechanisms of neck pain remains insufficient. Thus, this study aimed to identify the factors associated with preoperative and postoperative neck pain in patients with degenerative cervical myelopathy who underwent laminoplasty. Methods In this prospective multicenter study, we prospectively enrolled patients who were scheduled for laminoplasty for degenerative cervical myelopathy. The associations between different variables and the Numerical Pain Rating Scale (NRS) scores for neck pain were investigated using univariate and multiple linear regression models. Results In total, 92 patients were included in the current study. The univariate analysis showed that age, sex, cervical lordosis in neutral and extension, and thoracic kyphosis were significantly associated with the preoperative NRS score for neck pain; moreover, preoperative cervical lordosis in extension and range of motion and postoperative cervical lordosis in neutral, flexion, and extension were significantly associated with the postoperative NRS Scale score for neck pain. Stepwise multiple regression analysis showed that the independent factors contributing to preoperative neck pain were preoperative cervical lordosis in extension, sex, and age. The independent preoperative predictor and contributor to postoperative neck pain were preoperative cervical lordosis in extension and postoperative cervical lordosis in extension, respectively. Conclusions Cervical lordosis in extension showed significant association with neck pain in patients with degenerative cervical myelopathy. Therefore, when performing laminoplasty for patients with a low cervical lordosis in extension, attention should be paid to residual postoperative neck pain.

Study design Prospective observational cohort study. Objective To prospectively examine dysphagia after subaxial cervical spine surgery. Summary of background data Although dysphagia after anterior cervical spine surgery is common and well-studied, it has rarely been examined in posterior subaxial cervical spine surgery. Methods This study analyzed 191 consecutive patients (132 male, 59 female; mean age, 64.9 yrs) who underwent subaxial cervical spine surgery for degenerative disease and completed 1 year of follow-up. Anterior decompression with fusion (ADF) was performed in 87 patients, posterior decompression with fusion (PDF) in 21, and laminoplasty (LAMP) in 83. Dysphagia was evaluated by a self-administered questionnaire using the Bazaz dysphagia scale before, 6 months, and 1 year after surgery. Diagnosis, levels and number of operative segments, C2-7 lordotic angle (CL), O-C2 angle (OC2A), C2-7 range of motion (ROM), Japanese Orthopedic Association for cervical myelopathy (C-JOA) score, and neck pain visual analog scale (VAS) were examined. Results Thirty-two patients (16.8%) reported dysphagia before surgery. New dysphagia after surgery, defined as more than or equal to 1 grade worsening of the Bazaz score after surgery compared with the preoperative status, was observed in 38 patients (19.9%) at 6 months and 32 patients (16.8%) at 1 year. The incidence of new dysphagia at 1 year was 25.3% in the ADF group, 23.8% in the PDF group, and 6.0% in the LAMP group. Fusion surgery (ACDF or PDF) and increased CL after surgery were found as risk factors at 1 year in multivariate analysis; receiver operating characteristic analysis determined a postsurgical change in CL cutoff of 5°. Conclusion Fusion surgery and increased CL after surgery were risk factors for development of dysphagia after subaxial cervical spine surgery. Cervical alignment change due to anterior and posterior fusion surgery can cause postoperative dysphagia.Level of Evidence: 3.

Introduction Anterior decompression and fusion have shown favorable neurologic outcomes in patients with cervical myelopathy. However, implant migration sometimes occurs immediately after multilevel anterior cervical corpectomy with fusion (ACCF). Risk factors associated with early bone graft migration have not been precisely documented. The study aimed to investigate how frequently bone graft subsidence occurs after ACCF and to determine the factors affecting implant migration. Methods Forty-seven consecutive patients who underwent ACCF for ossification of the posterior longitudinal ligament at our hospital between 2007 and 2015 and were able to complete 1 year of follow-up were enrolled. Patients treated with hybrid fixation were excluded. Data on demographics and radiographic findings, namely, fused segment angle and fused segment height (FSH), were collected. Implant migration was defined as subsidence of >3 mm. The patients were divided into 2-segment (2F), 3-segment (3F), and ≥4-segment (4F) groups. Results were compared between the groups using one-way analysis of variance, the Mann-Whitney U test, and the chi-square test. Results Mean age was 61.6 years in the 2F group (n = 17), 62.1 years in the 3F group (n = 21), and 69 years in the 4F group (n = 9). There were no significant between-group differences in demographics or clinical characteristics. Implant subsidence occurred in 3 cases (17.6%) in the 2F group, 4 (19%) in the 3F group, and 3 (33.3%) in the 4F group. Revision surgery was required in 2 cases (1 patient each in the 3F and 4F groups). Logistic regression analysis showed a significant association of increased FSH and increased risk of postoperative implant subsidence. Conclusions A postoperative increase in FSH may affect graft stability and lead to early implant migration.

Background Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by heterotopic bone formation in the posterior longitudinal ligament of the spine. We know that the size and distribution of the ossified lesions in patients with OPLL are different in each case. However, the characteristics of the patients with radiologically severe cervical OPLL remain unknown. Methods The participants of our study were symptomatic patients with cervical OPLL who were diagnosed by standard radiographs of the cervical spine. Whole-spine CT data and demographic data such as age and sex were obtained from 20 institutions belonging to the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. According to the number of the levels involved by OPLL, we stratified the patients into two subgroups: severe group (S-group) and non-severe group (NS-group) to delineate the characteristics of radiologically severe patients with cervical OPLL. We also evaluated the most compressed level and the degree of occupying ratio of cervical spinal canal by OPLL at the most compressed level. Results A total of 234 patients with a mean age of 65 years were recruited. The S-group consisted of 48 patients (21%, 12 females and 36 males) and the NS-group consisted of 92 patients (79%, 22 females and 70 males). The mean age of males in the S-group (68 years old) was significantly higher than that of males in the NS-group (64 years old); however there was no significant difference in the mean age in females between the S-group (69 years old) and the NS-group (66 years old). No significant difference of body mass index, ossification of the nuchal ligament-positivity and presence of diabetes mellitus were found between the S- and the NS-group. Conclusions It is likely that the manner of extension of cervical OPLL is different between male and female patients.

STUDY DESIGN This was a retrospective cohort study using a nationwide inpatient database. OBJECTIVE The objective of this study was to evaluate the perioperative complications post-anterior fusion (AF) and posterior fusion (PF) for osteoporotic vertebral fractures (OVFs) with a large National Inpatient Database. SUMMARY OF BACKGROUND DATA OVF of the thoracolumbar spine often occur because of bone fragility and low-energy trauma in elderly patients. Though AF and PF are 2 representative surgical methods, there have been few studies focusing on perioperative complications of each method. MATERIALS AND METHODS The total 2446 (AF: 435 cases, PF: 2011 cases) patients who diagnosed thoracic or lumbar OVF and received either AF or PF were included from 2012 to 2016 with the Diagnosis Procedure Combination (DPC) database. After one-to-one propensity score-matching, total 866 cases were analyzed to evaluate systemic and local complication rates, reoperation rates, costs, and mortality. RESULTS A total of 433 pairs were made between the surgical procedures after matching. At least 1 systemic complication was seen in 26.6% of the AF group compared with 16.9% of the PF group (P=0.001). Specifically, the incidence of pulmonary embolism (P=0.045), urinary tract infection (P=0.012), and pleurisy (P=0.004) were significantly higher in the AF group. Blood transfusion (P=0.007) and the operation for systemic complications (P=0.020) were required more often in the AF group. The cost for hospitalization was also higher in the AF group (P

Study design Prospective cohort study. Objective To characterize a patient population with nonunion after acute osteoporotic vertebral fractures (OVFs) and compare the union and nonunion groups to identify risk factors for nonunion. Summary of background data While OVFs are the most common type of osteoporotic fracture, the predictive value of a clinical assessment for nonunion at 48 weeks after OVF has not been extensively studied. Methods This prospective multicenter cohort study included female patients aged 65 to 85 years with acute one-level osteoporotic compression fractures. In the radiographic analysis, the anterior vertebral body compression percentage was measured at 0, 12, and 48 weeks. Magnetic resonance imaging (MRI) was performed at enrollment and at 48 weeks to confirm the diagnosis and union status. The patient-reported outcome measures included scores on the European Quality of Life-5 Dimensions (EQ-5D), a visual analogue scale for low back pain, and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) at 0, 12, and 48 weeks. Results In total, 166 patients completed the 12-month follow-up, 29 of whom had nonunion. Patients with nonunion at 48 weeks after OVF had lower EQ-5D and JOABPEQ walking ability, social life function, mental health, and lumbar function scores than those with union at 48 weeks after injury. The independent risk factors for nonunion after OVF in the acute phase were a diffuse low type pattern on T1-weighted MRI and diffuse low and fluid type patterns on T2-weighted MRI. The anterior vertebral body compression percentage and JOABPEQ social life function scores were independent risk factors at 12 weeks. Conclusion A diffuse low type pattern on T1-weighted MRI and diffuse low and fluid type patterns on T2-weighted MRI were independent risk factors for nonunion in the acute phase. Patients who have acute OVFs with these risk factors should be carefully monitored for nonunion. Level of evidence 2.

Background The optimal surgical procedure for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) remains controversial because there are few comprehensive studies investigating the surgical methods. Therefore, we conducted a systematic review and meta-analysis to evaluate evidence in the literature and compare the surgical outcomes of anterior decompression with fusion (ADF) and laminoplasty (LAMP), which are representative procedures for cervical OPLL. Methods An extensive literature search was performed using PubMed, Embase, and the Cochrane Library to identify comparative studies of ADF and LAMP for cervical OPLL. The language was restricted to English, and the year of publication was from January 1980 to December 2018. We extracted outcomes from the studies, such as preoperative and postoperative Japanese Orthopaedic Association (JOA) score, cervical alignment, surgical complications and reoperation rate. Then, meta-analysis was performed for these surgical outcomes. Results Twelve studies were obtained, including 1 prospective cohort study and 11 retrospective cohort studies. In the meta-analysis, neurological recovery rate in JOA score was greater in ADF than in LAMP, especially in patients with a large canal occupying ratio (≥60%) and preoperative kyphotic alignment. ADF also exhibited more favorable results in postoperative cervical alignment. In contrast, operating time and intraoperative blood loss were greater in ADF. Surgical complications were more frequently seen in ADF, leading to higher rates of reoperation. Conclusions This systematic review and meta-analysis showed both the merits and shortcomings of ADF and LAMP. ADF resulted in more favorable neurological recovery compared to LAMP, especially for patients with massive OPLL and kyphotic alignment. Postoperative cervical lordosis was also better preserved in ADF. However, ADF was associated with greater surgical invasion and higher incidences of surgical complications.

Study design A prospective multicenter study. Objective This study aims to investigate the postoperative complications of anterior decompression with fusion (ADF) for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL). Summary of background data Surgical treatment for cervical OPLL has a high risk of various complications. ADF is reported to be effective for cervical OPLL, especially for massive OPLL. However, few studies have focused on the surgical complications of ADF. Methods We prospectively included 102 patients undergoing ADF for severe cervical OPLL with average canal occupying ratio of 49.8%. We evaluated systemic and local complications, neurological complications, and risk factors related to the postoperative complications. Results Frequently observed complications included graft/ implant complications (18.6%), neurological complications (11.8%), and cerebrospinal fluid leak (11.8%). Motor palsy involving only the upper extremity was found in nine patients (8.8%), and other motor palsies involving the lower extremities were found in three patients (2.9%). None of the preoperative factors were significantly associated with the occurrence of neurological palsies, whereas the number of operated levels was a significant factor related to the postoperative graft/implant complications (P = 0.003; odds ratio, 2.112). The incidence of graft/implant complications and related reoperation increased as the number of operated levels increased (especially four levels or more). Most motor palsies were observed immediately after surgery. Of the motor palsies in the bilateral upper extremities and palsies involving the lower extremities, 85.7% showed good recovery, whereas only 40% of unilateral upper extremity motor palsies showed good recovery during the follow-up period. Conclusion In ADF for cervical OPLL, the number of operated levels was a significant factor related to the postoperative complication. Specifically, the incidence of graft/implant complications and reoperation rate increased in ADF with four or more levels.Level of Evidence: 3.

Postoperative neck pain has been reported as an unsolved postoperative complication of surgery for cervical ossification of the posterior longitudinal ligament (OPLL). The aim of the present study was to elucidate factors having a significant association with postoperative deterioration of neck pain in cervical OPLL patients. We studied a cohort of patients in a prospective registry of 478 patients who had undergone cervical spine surgery for cervical OPLL. We excluded those without evaluation of preoperative neck pain. Therefore, 438 patients were included in the present study. Neck pain was evaluated with the visual analogue scale (VAS, 0–100 mm). Postoperative neck pain deterioration was defined as a ≥20 mm increase of VAS neck pain. Patient factors, neurological status, imaging factors and surgical factors were assessed. Univariate analyses followed by multivariate analysis using stepwise logistic regression was performed. Six months after surgery, 50 (11.6%) patients showed postoperative neck pain deterioration and 76 (17.4%) patients showed postoperative neck pain deterioration 2 years after surgery. Six months after surgery, the rate of neck pain deterioration was significantly higher in patients who had undergone posterior surgery. Two years after surgery, the number of levels fused was significantly correlated with neck pain deterioration.

Lateral lumbar interbody fusion (LLIF) is increasingly performed as corrective surgery for patients with adult spinal deformity (ASD). This paper compares the surgical results of LLIF and conventional posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) in ASD using a propensity score matching analysis. We retrospectively reviewed patients with ASD who received LLIF and PLIF/TLIF, and investigated patients’ backgrounds, radiographic parameters, and complications. The propensity scores were calculated from patients’ characteristics, including radiographic parameters and preoperative comorbidities, and one–to-one matching was performed. Propensity score matching produced 21 matched pairs of patients who underwent LLIF and PLIF/TLIF. All radiographic parameters significantly improved in both groups at the final follow-up compared with those of the preoperative period. The comparison between both groups demonstrated no significant difference in terms of postoperative pelvic tilt, lumbar lordosis (LL), or pelvic incidence–LL at the final follow-up. However, the sagittal vertical axis tended to be smaller in the LLIF at the final follow-up. Overall, perioperative and late complications were comparable in both procedures. However, LLIF procedures demonstrated significantly less intraoperative blood loss and a smaller incidence of postoperative epidural hematoma compared with PLIF/TLIF procedures in patients with ASD.

Chemonucleolysis with condoliase (chondroitin sulfate ABC endolyase) has been used to treat patients with lumbar disc herniation (LDH) in Japan since 2018. In this study, we retrospectively investigated clinical outcomes in patients who received an intradiscal condoliase injection for LDH and sought to identify significant predictors of good outcome.Indications for treatment were as follows: (1) unilateral leg pain with or without back pain, (2) nerve root compression caused by LDH confirmed on magnetic resonance imaging (MRI), and (3) leg pain resistant to at least 1 month of conservative treatment, including medication, nerve root block, or physical therapy. Patients with motor weakness or a history of severe allergy were excluded, as were those with the foraminal or sequestrated type of LDH. The injection was defined as effective if the numeric rating scale score for leg pain improved by ≥50% at 6 months post-treatment.A total of 52 patients (mean age, 45.0 years) were enrolled and classified according to whether the injection was effective (E group, n=40, 76.9%) or less effective (L group, n=9, 17.3%). Three patients (5.8%) underwent herniotomy for residual pain within 6 months of the injection. There were no severe adverse events. Reduction of herniation was seen on MRI more often in the E group than in the L group. The effectiveness in patients with transligamentous LDH was similar to that in patients with subligamentous LDH. High-intensity signal change in the area of LDH on pretreatment T2-weighted MRI was a significant predictor of successful leg pain relief.An intradiscal condoliase injection was a safe and effective treatment for painful radiculopathy caused by LDH. Leg pain was more likely to improve in patients with high-intensity signal change in the area of LDH before treatment.

Study design This was a retrospective observational study. Objective To assess the diagnostic value of procalcitonin (PCT) and neutrophil lymphocyte ratio (NLR) for predicting surgical site infection (SSI) in patients undergoing spinal instrumentation surgery, we analyzed a large consecutive cohort of patients who had undergone spinal instrumentation surgery. Summary of background data Although PCT and NLR are commonly used as markers for bacterial infection, the diagnostic value of these factors for predicting SSI in the context of spinal instrumentation surgery has not been extensively investigated. Methods We retrospectively investigated 242 patients who underwent spinal instrumentation surgery and evaluated the significance of various postoperative measures for predicting SSI, including PCT and NLR. We then determined the diagnostic cut-off values for these markers in the prediction of SSI using receiver operating characteristic curve analysis. Results Among the 242 patients analyzed, 10 were diagnosed with infection. Even though univariate analysis showed that neutrophil percentage and NLR at 6 to 7 days postoperatively were significant predictors for SSI, PCT at 6 to 7 days postoperatively did not differ significantly between the SSI and non-SSI groups. The cut-off value used for neutrophil percentage at 6 to 7 days postoperatively was more than 69.0% [sensitivity, 80.0%; specificity, 70.0%; area under the curve, 0.737]. The cut-off value used for NLR at 6 to 7 days postoperatively was 3.87 (sensitivity, 70.0%; specificity, 73.2%; area under the curve, 0.688). Conclusion Neutrophil percentage and NLR at 6 to 7 days postoperatively were more useful markers than PCT at 6 to 7 days postoperatively for early prediction of SSI in patients who had undergone spinal instrumentation surgery. Therefore, routine use of PCT as a predictor of postoperative infection is not supported by the results of this study. Level of evidence 4.

Prospective observational single-center study.To evaluate anterior decompression and fusion (ADF) or posterior surgery (PS) for patients with cervical spondylotic myelopathy (CSM) using the modified K-line (mK-line) and to compare clinical and radiologic outcomes between these 2 techniques.The authors have previously reported that insufficient posterior decompression is often seen after laminoplasty for CSM in patients with preoperative anterior clearance of the spinal cord4 mm on the basis of the mK-line. However, to our knowledge, no study has investigated the role, if any, of the mK-line in surgical decision making for patients with CSM.A total of 87 patients were enrolled who underwent surgery for treatment of CSM between 2011 and 2015 at our hospital and who could be followed up for at least 2 years. ADF was selected as a more favorable procedure than PS in patients with anterior spinal clearance of4 mm on preoperative midsagittal magnetic resonance imaging. On the basis of the Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy, the rate of recovery of the JOA scores at 2 years after surgery was investigated as a clinical outcome to compare these 2 groups.Mean age was 65.1 (±12.9) years in the ADF group (n=26) and 70.5 (±8.6) years in the PS group (n=61). In the PS group, 10 patients underwent posterior decompression with fusion. Mean preoperative and postoperative JOA scores were 10.5 and 14.1 points in the ADF group and 9.8 and 13.1 points in the PS group, respectively, showing no significant difference in recovery rate of JOA score between the ADF (58.9%) and PS (47.1%) groups. However, patients with a minimum interval between the mK-line and the anterior compression factor on the midsagittal image (minimum interval of the spinal cord)4 mm tended to have unsatisfactory outcomes (recovery rate 29.6%) compared with patients with minimum interval of the spinal cord4 mm (53.6%, P=0.07) in the PS group.Preoperative intervention using the mK-line is useful to predict residual cord compression and might homogenize postoperative clinical outcomes in both anterior surgery and PS.

Background Surgical procedures for cervical myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) are often chosen based on OPLL size and cervical spine alignment. Recently, cervical sagittal alignment based on sagittal vertical axis (SVA) has received increased attention as an important determinant of radiological and clinical outcomes after surgery. This study aimed to investigate the impact of SVA-based cervical sagittal alignment on surgical treatment for cervical OPLL by reviewing a previous retrospective cohort in which its concept was not taken into account in the surgical procedure choices. Methods We reviewed a total of 96 consecutive patients who underwent surgery for cervical myelopathy caused by OPLL from 2008 to 2014. We performed anterior decompression with fusion (ADF) or posterior decompression with fusion (PDF) on patients with massive OPLL or kyphotic alignment, and we performed laminoplasty (LAMP) on patients without massive OPLL or kyphotic alignment. CSVA (center of gravity of the head - C7 SVA), CL (C2-7 lordotic angle) and C7 slope were measured in cervical X-ray at standing position. Clinical results were evaluated using C-JOA score. We divided patients into two subgroups based on the preoperative CSVA: the Low-CSVA (CSVA Results In the Low-CSVA subgroup, none of the three operations had an effect on the CL. In contrast, in the High-CSVA subgroup, while ADF and PDF had no effect on the CL, LAMP worsened the CL postoperatively. The recovery rates of the C-JOA scores in the Low-CSVA subgroup showed no significant differences among the three operations; however in the High-CSVA subgroup, LAMP resulted in worse recovery rate of the C-JOA score than ADF or PDF. Conclusions LAMP is not suitable for patients with cervical myelopathy caused by OPLL who have high CSVA alignment, even in cases without massive OPLL or kyphotic alignment.

Study Design: Retrospective single-center study. Objectives: K-line is a decision-making tool to determine the appropriate surgical procedures for patients with cervical ossification of the posterior longitudinal ligament (C-OPLL). Laminoplasty (LAMP) is one of the standard surgical procedures indicated on the basis of K-line measurements (+: OPLL does not cross the K-line). We investigated the impact of K-line tilt, a radiographic parameter of cervical sagittal balance measured using the K-line, on surgical outcomes after LAMP. Methods: The study included 62 consecutive patients with K-line (+) C-OPLL who underwent LAMP. The following preoperative and postoperative radiographic measurements were evaluated: (1) the K-line, (2) K-line tilt (an angle between the K-line and vertical line), (3) center of gravity of the head –C7 sagittal vertical axis, (4) C2–C7 lordotic angle, (5) C7 slope, and (6) C2–C7 range of motion. Clinical results were evaluated using the Japanese Orthopedic Association scoring system for cervical myelopathy (C-JOA score). Results: All the patients had non-kyphotic cervical alignment (CL ≥ 0°) preoperatively; however, kyphotic deformity (CL < 0°) was observed in 6 patients (9.7%) postoperatively. The recovery rate of the C-JOA scores was poor in the kyphotic deformity (+) group (7.8%) than in the kyphotic deformity (−) group (47.5%). The K-line tilt was identified to be a preoperative risk factor in the multivariate analysis, and the cutoff K-line tilt for predicting the postoperative kyphotic deformity was 20°. Conclusions: LAMP is not suitable for K-line (+) C-OPLL patients with K-line tilts >20°.