Comparison of Postoperative Complications and Outcomes in Anterior Cervical Spine Surgery: Ossification of the Posterior Longitudinal Ligament Versus Cervical Spondylotic Myelopathy.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To compare the frequency of complications and outcomes between patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine and those with cervical spondylotic myelopathy (CSM) who underwent anterior surgery. SUMMARY OF BACKGROUND DATA: Anterior cervical spine surgery for OPLL is an effective surgical procedure; however, it is complex and technically demanding compared with the procedure for CSM. Few reports have compared postoperative complications and clinical outcomes after anterior surgeries between the 2 pathologies. METHODS: Among 1434 patients who underwent anterior cervical spine surgery at 3 spine centers within the same spine research group from January 2011 to March 2021, 333 patients with OPLL and 488 patients with CSM were retrospectively evaluated. Demographics, postoperative complications, and outcomes were reviewed by analyzing medical records. In-hospital and postdischarge postoperative complications were investigated. Postoperative outcomes were evaluated 1 year after the surgery using the Japanese Orthopaedic Association score. RESULTS: Patients with OPLL had more comorbid diabetes mellitus preoperatively than patients with CSM ( P <0.001). Anterior cervical corpectomies were more often performed in patients with OPLL than in those with CSM (73.3% and 14.5%). In-hospital complications, such as reoperation, cerebrospinal fluid leak, C5 palsy, graft complications, hoarseness, and upper airway complications, occurred significantly more often in patients with OPLL. Complications after discharge, such as complications of the graft bone/cage and hoarseness, were significantly more common in patients with OPLL. The recovery rate of the Japanese Orthopaedic Association score 1 year postoperatively was similar between patients with OPLL and those with CSM. CONCLUSION: The present study demonstrated that complications, both in-hospital and after discharge following anterior spine surgery, occurred more frequently in patients with OPLL than in those with CSM.

The lower Osteotomy Level is Associated With Decreased Revision Surgery Due to Mechanical Complications After Three-Column Osteotomy in Patients With Adult Spinal Deformity: A Multi-Institutional Retrospective Study.

STUDY DESIGN: A multi-institutional retrospective study. OBJECTIVES: To investigate risk factors of mechanical failure in three-column osteotomy (3COs) in patients with adult spinal deformity (ASD), focusing on the osteotomy level. METHODS: We retrospectively reviewed 111 patients with ASD who underwent 3COs with at least 2 years of follow-up. Radiographic parameters, clinical data on early and late postoperative complications were collected. Surgical outcomes were compared between the low-level osteotomy group and the high-level osteotomy group: osteotomy level of L3 or lower group (LO group, n = 60) and osteotomy of L2 or higher group (HO group, n = 51). RESULTS: Of the 111 patients, 25 needed revision surgery for mechanical complication (mechanical failure). A lower t-score (odds ratio [OR] .39 P = .002) and being in the HO group (OR 4.54, P = .03) were independently associated with mechanical failure. In the analysis divided by the osteotomy level (LO and HO), no difference in early complications or neurological complications was found between the two groups. The rates of overall mechanical complications, rod failure, and mechanical failure were significantly higher in the HO group than in the LO group. After propensity score matching, mechanical complications and failures were still significantly more observed in the HO group than in the LO group (P = .01 and .029, respectively). CONCLUSIONS: A lower t-score and osteotomy of L2 or higher were associated with increased risks of mechanical failure. Lower osteotomy was associated with better correction of sagittal balance and a lower rate of mechanical complications.

Augmented Reality Support for Anterior Decompression and Fusion Using Floating Method for Cervical Ossification of the Posterior Longitudinal Ligament.

Anterior decompression and fusion (ADF) using the floating method for cervical ossification of the posterior longitudinal ligament (OPLL) is an ideal surgical technique, but it has a specific risk of insufficient decompression caused by the impingement of residual ossification. Augmented reality (AR) support is a novel technology that enables the superimposition of images onto the view of a surgical field. AR technology was applied to ADF for cervical OPLL to facilitate intraoperative anatomical orientation and OPLL identification. In total, 14 patients with cervical OPLL underwent ADF with microscopic AR support. The outline of the OPLL and the bilateral vertebral arteries was marked after intraoperative CT, and the reconstructed 3D image data were transferred and linked to the microscope. The AR microscopic view enabled us to visualize the ossification outline, which could not be seen directly in the surgical field, and allowed sufficient decompression of the ossification. Neurological disturbances were improved in all patients. No cases of serious complications, such as major intraoperative bleeding or reoperation due to the postoperative impingement of the floating OPLL, were registered. To our knowledge, this is the first report of the introduction of microscopic AR into ADF using the floating method for cervical OPLL with favorable clinical results.

Prospective Comparative Study of Dysphagia after Subaxial Cervical Spine Surgery: Cervical Spondylotic Myelopathy and Posterior Longitudinal Ligament Ossification.

We prospectively investigated the postoperative dysphagia in cervical posterior longitudinal ligament ossification (C-OPLL) and cervical spondylotic myelopathy (CSM) to identify the risk factors of each disease and the incidence. A series of 55 cases with C-OPLL: 13 anterior decompression with fusion (ADF), 16 posterior decompression with fusion (PDF), and 26 laminoplasty (LAMP), and a series of 123 cases with CSM: 61 ADF, 5 PDF, and 57 LAMP, were included. Vertebral level, number of segments, approach, and with or without fusion, and pre and postoperative values of Bazaz dysphagia score, C2-7 lordotic angle (∠C2-7), cervical range of motion, O-C2 lordotic angle, cervical Japanese Orthopedic Association score, and visual analog scale for neck pain were investigated. New dysphagia was defined as an increase in the Bazaz dysphagia score by one grade or more than one year after surgery. New dysphagia occurred in 12 cases with C-OPLL; 6 with ADF (46.2%), 4 with PDF (25%), 2 with LAMP (7.7%), and in 19 cases with CSM; 15 with ADF (24.6%), 1 with PDF (20%), and 3 with LAMP (1.8%). There was no significant difference in the incidence between the two diseases. Multivariate analysis demonstrated that increased ∠C2-7 was a risk factor for both diseases.

Effectiveness of Lumbosacral Orthosis After Discectomy for Lumbar Disk Herniation: A Prospective Comparative Study.

STUDY DESIGN: A prospective comparative study. OBJECTIVE: To investigate the benefits of postoperative application of lumbosacral orthosis after single-level discectomy for lumbar disk herniation (LDH). SUMMARY OF BACKGROUND DATA: Although many surgeons use postoperative lumbosacral orthosis for patients with LDH, there is no clear evidence to support or deny its effectiveness. MATERIALS AND METHODS: Ninety-nine consecutive patients who underwent the microscopic discectomy were included. They were divided into two groups: orthosis group and nonorthosis group, before surgery. The recurrence rate and reoperation rate were compared between the two groups at four-week, six-month, and one-year follow-up. Japanese Orthopaedic Association Score for lumbar spine (L-JOA score) at two-week and one-year follow-up, lower extremities and low back pain's visual analog scale (VAS) and Oswestry Disability Index (ODI) at six-month and one-year follow-up were compared. RESULTS: Forty-two patients in the orthosis group and 39 patients in the nonorthosis group were followed up for at least one-year after surgery. Recurrence occurred in three patients (7.1%) in the orthosis group and six (15.4%) in the nonorthosis group within one-year. Two patients (4.8%) in the orthosis group and two patients (5.1%) in the nonorthosis group underwent reoperation. There were no significant intergroup differences in the recurrence rate and in the reoperation rate. No significant difference was also observed between the two groups in L-JOA score, ODI, VAS of low back pain, and leg pain at one-year after surgery. Furthermore, at any other follow-up period, no significant differences were observed between the two groups in recurrence rate, reoperation rate, L-JOA score, VAS of low back/leg pain, or ODI. CONCLUSIONS: The use of a postoperative orthosis did not reduce recurrence or reoperation rates, nor did it improve postoperative clinical symptoms. The routine use of an orthosis may not be necessary after single-level lumbar discectomy.

Detecting ossification of the posterior longitudinal ligament on plain radiographs using a deep convolutional neural network: a pilot study.

BACKGROUND CONTEXT: 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. PURPOSE: The aim of our research was to evaluate the performance of a CNN model for diagnosing cervical OPLL. STUDY DESIGN AND SETTING: Diagnostic image study. PATIENT SAMPLE: This study included 50 patients with cervical OPLL, and 50 control patients with plain radiographs. OUTCOME MEASURES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: The CNN model had successful diagnostic accuracy and sufficient specificity in the diagnosis of OPLL.

Anterior Cervical Corpectomy with Fusion versus Anterior Hybrid Fusion Surgery for Patients with Severe Ossification of the Posterior Longitudinal Ligament Involving Three or More Levels: A Retrospective Comparative Study.

Various studies have found a high incidence of early graft dislodgement after multilevel corpectomy. Although a hybrid fusion technique was developed to resolve implant failure, the hybrid and conventional techniques have not been clearly compared in terms of perioperative complications in patients with severe ossification of the posterior longitudinal ligament (OPLL) involving three or more levels. The purpose of this study was to compare clinical and radiologic outcomes between anterior cervical corpectomy with fusion (ACCF) and anterior hybrid fusion for the treatment of multilevel cervical OPLL. We therefore retrospectively reviewed the clinical and radiologic data of 53 consecutive patients who underwent anterior fusion to treat cervical OPLL: 30 underwent ACCF and 23 underwent anterior hybrid fusion. All patients completed 2 years of follow-ups. Implant migration was defined as subsidence > 3 mm. There were no significant differences in demographics or clinical characteristics between the ACCF and hybrid groups. Early implant failure occurred significantly more frequently in the ACCF group (5 cases, 16.7%) compared with the hybrid group (0 cases, 0%). The fusion rate was 80% in the ACCF group and 100% in the hybrid group. Although both procedures can achieve satisfactory neurologic outcomes for multilevel OPLL patients, hybrid fusion likely provides better biomechanical stability than the conventional ACCF technique.

Predictive Factors Affecting Surgical Outcomes in Patients with Degenerative Lumbar Spondylolisthesis.

STUDY DESIGN: Post-hoc analysis of 5-year follow-up data from a prospective randomized multicenter trial. OBJECTIVE: The purpose of this study was to identify preoperative factors that predict poor postoperative outcomes and define clinically important abnormal instabilities in degenerative lumbar spondylolisthesis. SUMMARY OF BACKGROUND DATA: Current evidence regarding prognostic factors affecting clinical outcomes after surgery for degenerative lumbar spondylolisthesis is still limited. Moreover, there is no consensus regarding parameters that define clinically important abnormal instability in patients with degenerative lumbar spondylolisthesis. METHODS: This post-hoc analysis from a prospective randomized trial that compared the effectiveness of decompression, decompression with fusion, and decompression with stabilization for degenerative lumbar spondylolisthesis at the L4/5 level included 70 patients with a 5-year follow-up period. We investigated the correlation between the postoperative recovery rate and preoperative radiographic parameters. We then investigated differences between the good recovery and poor recovery groups. RESULTS: Japanese Orthopaedic Association and visual analogue scale scores improved postoperatively. Of the 70 patients analyzed, 13 were judged to be in the poor recovery group based on their recovery rate. The recovery rate significantly correlated with the intervertebral angle at L4/5. Univariate analysis showed that while the degree of vertebral slippage and the presence of angulation were not associated with poor recovery, the intervertebral angle at L4/5 and the presence of translation were associated with poor recovery. Lastly, multiple stepwise logistic regression analysis revealed the intervertebral angle at L4/5 and the presence of translation as independent predictors of poor recovery after surgery for lumbar degenerative spondylolisthesis. CONCLUSION: While the degree of vertebral slippage and the presence of angulation were not associated with poor recovery after surgery for lumbar degenerative spondylolisthesis, postoperative outcomes were associated with the intervertebral angle and the presence of translation. Careful preoperative measurement of these factors may help to predict poor postoperative outcomes.Level of Evidence: 3.

Preoperative risk factors for delirium in patients aged ≥75 years undergoing spinal surgery: a retrospective study.

OBJECTIVE: The increasing number of spinal surgeries being performed in the elderly has increased the incidence of postoperative delirium. The prediction of delirium is complex, and few studies have been performed to examine the preoperative risk factors for delirium after spinal surgery in the elderly. This study was performed to clarify such risk factors in patients aged ≥75 years undergoing spinal surgery. METHOD: This retrospective observational study included 299 patients aged ≥75 years. Comorbidities, medication history, preoperative examination findings, surgery-related characteristics, and health scale assessments, including the 36-Item Short-Form Survey (SF-36) score and prognostic nutritional index (PNI), were examined as potential risk factors for delirium. RESULTS: Delirium occurred in 53 patients (17.7%). The preoperative risk factors for delirium were a history of stroke and mental disorders, hypnotic drug use, malnutrition, hyponatremia, anemia, respiratory dysfunction, and cervical surgery. Logistic regression analysis demonstrated that the independent predictors of delirium were a history of stroke, non-benzodiazepine hypnotic drug use, preoperative hyponatremia, the PNI, and the SF-36 physical component summary (PCS) score. CONCLUSIONS: Independent preoperative predictors of delirium in elderly patients undergoing spinal surgery included a history of stroke, non-benzodiazepine hypnotic drug use, preoperative hyponatremia, the PNI, and the SF-36 PCS score.

Intra-articular Injection of Pure Platelet-Rich Plasma Is the Most Effective Treatment for Joint Pain by Modulating Synovial Inflammation and Calcitonin Gene-Related Peptide Expression in a Rat Arthritis Model.

BACKGROUND: Platelet-rich plasma (PRP) has emerged as a treatment for osteoarthritis (OA). However, the effect that leukocyte concentrations in PRP have on OA remains unclear. PURPOSE: To clarify the optimal PRP formulation for OA treatment by comparing pure PRP, leukocyte-poor PRP (LP-PRP), and leukocyte-rich PRP (LR-PRP) in a rat arthritis model. STUDY DESIGN: Controlled laboratory study. METHODS: Knee arthritis was induced bilaterally in male Wistar rats with intra-articular injections of monosodium iodoacetate (MIA) on day 0. Rats were randomly assigned to 1 of 3 treatment groups (pure PRP, LP-PRP, and LR-PRP). On day 1, allogenic PRP was injected into the right knee of rats and phosphate-buffered saline was injected into the left knee as a control. Weight distribution on the hindlimbs was measured for 14 days to assess pain behavior. Rats were euthanized at day 5 or 14 for histological assessment of synovial tissue and cartilage. Immunohistochemical staining of calcitonin gene-related peptide (CGRP) and α-smooth muscle actin was performed to determine the mechanism of pain relief induced by the PRP preparations. RESULTS: In all groups, PRP increased the load-sharing ratio on PRP-injected knees, with pure PRP eliciting the largest effect among the 3 kinds of PRP (P < .05). Structural changes in the synovial tissue were significantly inhibited in the pure-PRP group compared with the control group after both 5 and 14 days (P < .001 and P = .025, respectively), whereas no significant difference was found between the control, LP-PRP, and LR-PRP groups. An inhibitory effect on cartilage degeneration was observed only in the pure-PRP group on day 14. Pure PRP also significantly inhibited expression of CGRP-positive nerve fibers in the infrapatellar fat pad compared with the other groups (P < .05). CONCLUSION: In an MIA-induced arthritis model, pure PRP injection was the most effective treatment for reduction of pain-related behavior and inhibition of synovial inflammation and pain sensitization. CLINICAL RELEVANCE: PRP formulations should be optimized for each specific disease. This study shows the superiority of pure PRP for treatment of arthritis and joint pain.

Fibrotic changes in the infrapatellar fat pad induce new vessel formation and sensory nerve fiber endings that associate prolonged pain.

The infrapatellar fat pad (IFP) contains nerve fiber endings and is considered to play an important role in the perception of knee pain. However, it is unclear whether and to what degree prolonged pain influences the nociceptive role of the IFP. To answer this question, we established a novel rat model of knee pain in which inflammation is restricted to the IFP. Rats received a single intra-IFP injection of monoiodoacetic acid (MIA) (0.2 mg/10 µL or 1.0 mg/10 µL) in the left knee and a phosphate-buffered saline (10 µL) injection in the right knee as a control. Pain-avoidance behavior and histological changes of the knee joint were measured at multiple time points up to 28 days after MIA injection. Histological analysis showed a transient inflammatory response in the IFP body in the 0.2-mg model, whereas prolonged inflammation followed by fibrotic changes was observed in the 1.0-mg model. Subtle histological alterations were observed in the articular cartilage and IFP surface regardless of the dose. The pain-avoidance behavior test indicated the development of prolonged knee pain throughout the experimental period in the 1.0-mg group. Histological assessments showed a significant increase in calcitonin gene-related peptide (CGRP)-positive nerve fiber endings inside IFPs with fibrosis in newly vascularized surrounding regions. These data suggest that irreversible fibrotic changes in the IFP induce the formation of new vessels and CGRP-positive nerve fiber endings that associate prolonged pain in the joint.

Is Modified K-line a Powerful Tool of Surgical Decision Making for Patients With Cervical Spondylotic Myelopathy?

STUDY DESIGN: Prospective observational single-center study. OBJECTIVE: 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. SUMMARY OF BACKGROUND DATA: 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 cord <4 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. METHODS: 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 of <4 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. RESULTS: 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 cord >4 mm (53.6%, P=0.07) in the PS group. CONCLUSION: 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.

Time course analyses of structural changes in the infrapatellar fat pad and synovial membrane during inflammation-induced persistent pain development in rat knee joint.

BACKGROUND: Osteoarthritis (OA) is a common joint disease in aging societies, which is accompanied by chronic inflammation and degeneration of the joint structure. Inflammation of the infrapatellar fat pad (IFP) and synovial membrane (IFP surface) plays essential roles in persistent pain development in patients with OA. To identify the point during the inflammatory process critical for persistent pain development, we performed a time course histological analysis in a rat arthritis model. METHODS: Wistar rats received single intra-articular injection of monoiodoacetic acid (MIA, 0.2 or 1.0 mg/30 µL) in the right knees or phosphate-buffered saline (PBS, 30 µL) as a control in the left knees. Pain avoidance behaviors (weight-bearing asymmetry and tactile hypersensitivity of the plantar surface of the hind paw) were evaluated on days 0, 1, 3, 5, 7, and 14 after injection. Histological assessments of the knee joint were performed on days 0, 1, 3, 5, and 7 after MIA injection. RESULTS: Weight-bearing asymmetry was observed along with the onset of acute inflammation in both the low- (0.2 mg) and high-dose (1.0 mg) groups. In the low-dose group, weight-bearing asymmetry was completely reversed on day 10, indicating that joint pain seemed to alleviate between days 7 and 10. In contrast, we observed persistent joint pain after day 10 in the high-dose group. Histological assessments of the high-dose group indicated that the initial sign of inflammatory responses was observed in the perivascular region inside the IFP. Inflammatory cell infiltration from the perivascular region to the parenchymal region of the IFP was observed on day 3 and reached the IFP surface (synovial membrane) on day 7. Extensive fibrosis throughout the IFP was observed between days 5 and 7 after MIA injection. CONCLUSION: Our data indicated that acute joint pain occurs along with the onset of acute inflammatory process. Irreversible structural changes in the IFP, such as extensive fibrosis, are observed prior to persistent pain development. Thus, we consider that this process may play important roles in persistent pain development.

Persistent synovial inflammation plays important roles in persistent pain development in the rat knee before cartilage degradation reaches the subchondral bone.

BACKGROUND: The major complaint of knee osteoarthritis (OA) is persistent pain. Unlike acute inflammatory pain, persistent pain is usually difficult to manage since its pathology is not fully understood. To elucidate the underlying mechanisms of persistent pain, we established 2 different inflammation-induced arthritis models by injecting monoiodo-acetic acid (MIA) into the joint cavity and performed integrated analyses of the structural changes in the synovial tissue and articular cartilage, sensory neuron rearrangement, and pain avoidance behavior in a rat arthritis model. METHODS: Male Wistar rats received intra-articular injections of MIA (0.2 mg/30 µL, low-dose group; 1 mg/30 µL, high-dose group) in the right knee and phosphate buffered saline (PBS; 30 µL, control group) in the left knee. Fluorogold (FG), a retrograde neural tracer, was used to label the nerve fibers for the identification of sensory neurons that dominate the joints in the dorsal root ganglion (DRG). Both knees were subjected to the intra-articular injection of 2% FG in PBS (5 µL) under anesthesia 5-7 days prior to sacrifice. We performed pain avoidance behavior tests (incapacitance and von Frey tests) at 0, 1, 3, 5, 7, 14, 21, and 28 days. At 5, 14, and 28 days, the rats were sacrificed and the knee joint and DRG were excised for histological assessment. The knee joints were stained with hematoxylin and eosin, safranin O, and calcitonin gene-related peptide (CGRP). The DRG were immunostained with CGRP. RESULTS: A transient inflammatory response followed by mild articular cartilage degeneration was observed in the low-dose MIA model versus persistent inflammation with structural changes in the synovial tissue (fibrosis) in the high-dose model. In the high-dose model, full-thickness cartilage degeneration was observed within 2 weeks post-MIA injection. The pain avoidance behavior tests indicated that persistent synovial inflammation and structural changes of the infrapatellar fat pad may play important roles in persistent knee joint pain before the articular cartilage degeneration reaches the subchondral bone. CONCLUSIONS: Transient inflammation without structural changes of the synovial tissues did not induce persistent pain in the rat knee joint before degradation of the articular cartilage reached the subchondral bone plate.

Clinical and radiologic outcomes of bone grafted and non-bone grafted double-door laminoplasty, the modified Kirita-Miyazaki method, for treatment of cervical spondylotic myelopathy: Five-year follow-up.

PURPOSE: To clarify whether there is any difference in mid-term clinical and radiologic outcomes between bone-grafted laminoplasty (BG LAMP) and non-bone-grafted laminoplasty (non-BG LAMP) when used to treat cervical spondylotic myelopathy. BACKGROUND: Conventional BG LAMP includes bone grafting at the lamina hinge site to prevent closure of the lamina postoperatively, but it often results in segmental fusion and sometimes causes loss of cervical mobility and lordotic alignment. Non-BG LAMP can now be performed to address this problem and preserve mobility postoperatively. However, there have been no studies comparing BG LAMP and non-BG LAMP to date. METHODS: Forty-one patients who underwent BG LAMP (n = 24) or non-BG LAMP (n = 17) and had 5 years of follow-up were enrolled in the study. Neurological status was assessed preoperatively and postoperatively using the Japanese Orthopedic Association (JOA) scoring system. The Numeric Rating Scale (NRS) was used to assess neck pain after surgery at the final visit. Radiographic parameters were evaluated at 1, 3, and 5 years after surgery. Postoperative segmental fusion was defined as the level at which the segmental flexion-extension range of motion was <1°. RESULTS: There was no significant difference in JOA score or recovery rate between the groups. NRS score was significantly lower in the BG group, indicating less neck pain (P < .01). The lordotic angle and range of motion at C2-C7 were significantly decreased in the BG group (P < .05). The segmental fusion was evident from 1 year postoperatively in both groups, but the fusion rate was significantly higher in the BG group (P < .05). CONCLUSIONS: Neurologic outcomes were similar between the two groups, whereas axial symptom was lower in the BG group than in the non-BG group. LEVEL OF EVIDENCE: Ⅳ.