Five-year follow-up evaluation of surgical treatment for cervical myelopathy caused by ossification of the posterior longitudinal ligament: a prospective comparative study of anterior decompression and fusion with floating method versus laminoplasty

[Successful surgical treatment of patient with cervical myelopathy due to ossification of the posterior longitudinal ligament: a rare clinical observation and literature review]

The authors describe the result of combined surgical treatment of a patient with symptomatic multiple-level cervical spine stenosis following ossification of posterior longitudinal ligament. The first stage included decompressive laminectomy and cervical spine fusion using a screw. At the second stage, C_IV-C_V-C_VI-C_VII corporectomy with total resection of the ossified posterior longitudinal ligament and C_III-Th_I corporodesis with a bone autograft were carried out. This approach was valuable to minimize the risk of iatrogenic damage to the spinal cord, eliminate long spinal stenosis and perform circular fusion of the cervical spine. These measures led to regression of cervical myelopathy symptoms. A brief review is presented.

Associations between Clinical Symptoms and Degree of Ossification in Patients with Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multi-Institutional Cross-Sectional Study

This study aimed to clarify whether ossification predisposition influences clinical symptoms including pain, restriction of activities of daily living, and quality of life in patients with cervical ossification of the posterior longitudinal ligament (OPLL). Cervical ossification predisposition potentially causes neurologic dysfunction, but the relationship between clinical symptoms and radiologic severity of OPLL has not yet been investigated. Data were prospectively collected from 16 institutions across Japan. We enrolled 239 patients with cervical OPLL. The primary outcomes were patient-reported outcomes, including visual analog scale (VAS) pain scores and other questionnaires. Whole-spine computed tomography images were obtained, and correlations were investigated between clinical symptoms and radiologic findings, including the distribution of OPLL, the sum of the levels where OPLL was present (OP-index), and the canal narrowing ratio (CNR) grade. The cervical OP-index was Grade 1 in 113 patients, Grade 2 in 90, and Grade 3 in 36. No significant correlations were found between radiologic outcomes and VAS pain scores. The cervical OP-index was associated with lower extremity function, social dysfunction, and locomotive function. The CNR grade was not correlated with clinical symptoms, but Grade 4 was associated with lower extremity dysfunction. Thickness and extension of ossified lesions may be associated with lower extremity dysfunction in cervical OPLL.

Anterior Decompression and Fusion Versus Laminoplasty for Cervical Myelopathy Caused by Soft Disk Herniation: A Long-term Prospective Multicenter Study

STUDY DESIGN

A prospective multicenter study.

OBJECTIVE

The purpose of this study was to determine whether laminoplasty (LP) is comparable for myelopathy caused by cervical disk herniation (CDH).

SUMMARY OF BACKGROUND DATA

Anterior decompression and fusion (ADF) has conventionally been used for myelopathy caused by CDH with stable outcomes. However, recurrence of myelopathy due to adjacent segment degeneration are its drawbacks. The efficacy of LP without discectomy has been sporadically reported, but no long-term prospective study has been conducted to verify it.

MATERIALS AND METHODS

Patients with cervical myelopathy caused by CDH were studied. The first 30 patients and the next 30 patients were treated with ADF and LP, respectively. The outcomes were compared between the 22 ADF patients and the 20 LP patients who had completed the follow-up examination scheduled 10 years after surgery.

RESULTS

There was no statistically significant difference in the postoperative severity or recovery rate of myelopathy between the 2 groups 10 years after surgery. One patient in the ADF group underwent LP for secondary myelopathy due to adjacent segment degeneration 2 years after the surgery. Reoperation was not required for patients in the LP group. Postoperative neck pain was significantly more severe in the LP group than in the ADF group.

CONCLUSIONS

ADF and LP for cervical myelopathy caused by CDH achieve similarly favorable outcomes. Recurrence of myelopathy caused by adjacent segment degeneration is a disadvantage of ADF while residual neck pain is a disadvantage of LP.

Fate of Ossification of Posterior Longitudinal Ligament Following Anterior Cervical Fusion: Progression of Cervical Ossification of Posterior Longitudinal Ligament After Vertebral Body Sliding Osteotomy or Laminoplasty

OBJECTIVE

In the treatment of ossification of posterior longitudinal ligament (OPLL)-induced cervical myelopathy, laminoplasty (LMP) is the most widely used surgical procedure. However, the progression of ossification masses is a well-known complication of LMP. This study aimed to investigate whether the novel anterior cervical decompression technique (vertebral body sliding osteotomy; VBSO) based on anterior column fusion suppresses the progression of OPLL compared with motion-preserving posterior decompression surgery (LMP).

METHODS

All 77 consecutive patients (VBSO group, n = 33; LMP group, n = 44) who underwent VBSO or LMP for cervical OPLL at our institute between January 2012 and November 2017 were included. A total of 62 and 86 cervical motion segments in the VBSO and LMP groups were investigated, respectively. The OPLL thickness was measured twice (immediate postoperative and final follow-up), and the change of OPLL thickness was compared between the 2 groups.

RESULTS

The increase in OPLL thickness in the VBSO group (-0.18 ± 0.24 mm) was significantly smaller than that in the LMP group (1.0 ± 0.9 mm, P < 0.001). Interestingly, in some patients, suppressed OPLL progression and decreased OPLL thickness were observed.

CONCLUSIONS

The solid fusion of the anterior column by VBSO is associated with the lower incidence of OPLL growth and potential for growth arrest.

Increased Height of Fused Segments Contributes to Early-Phase Strut Subsidence after Anterior Cervical Corpectomy with Fusion for Multilevel Ossification of the Posterior Longitudinal Ligament

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.

Comparison of Clinical and Radiographic Outcomes of Laminoplasty, Anterior Decompression With Fusion, and Posterior Decompression With Fusion for Degenerative Cervical Myelopathy: A Prospective Multicenter Study

STUDY DESIGN

Prospective multicenter study.

OBJECTIVE

The aim of this study was to compare the clinical and radiographic results of laminoplasty (LAMP), anterior decompression with fusion (ADF), and posterior decompression with fusion (PDF) for degenerative cervical myelopathy (DCM).

SUMMARY OF BACKGROUND DATA

Although ADF, LAMP, and PDF have been performed for DCM, little is known about the difference in impact of these surgical treatments on clinical and radiographic outcomes.

METHODS

We prospectively enrolled patients who were scheduled for surgery for DCM and compared the clinical and radiographic results of ADF, LAMP, and PDF.

RESULTS

In total, 171 patients completed the 1-year follow-up. Regarding clinical outcomes, the Japanese Orthopedic Association score for the assessment of cervical myelopathy (C-JOA score), European Quality of Life-5 Dimensions (EQ-5D), and Neck Disability Index (NDI) scores improved in all groups postoperatively. However, no significant differences were found in C-JOA, EQ-5D, and NDI scores and recovery rate among the groups. Regarding radiographic parameters, although the operation had no effect on cervical lordosis (CL) and the C2-7 sagittal vertical axis (SVA) in the ADF group, they worsened in the LAMP and PDF group. Although there were no significant differences in any preoperative radiographic parameters within the ADF and LAMP group, CL was significantly lower and the C2-7 SVA was significantly higher in the nonrecovery group within the PDF group. Logistic regression analysis showed that preoperative lower CL was an independent risk factor for poor recovery in the PDF group.

CONCLUSION

Although groups showed no significant differences in clinical outcomes, cervical alignment worsened after surgery in the LAMP and PDF groups. Within the PDF group, lower CL was an independent risk factor for poor recovery. Therefore, the indications for PDF in DCM patients with preoperative kyphotic alignment should be carefully considered.

LEVEL OF EVIDENCE

3.

Vertebral Body Sliding Osteotomy for Cervical Myelopathy With Rigid Kyphosis

Cervical spondylotic myelopathy is surgically demanding when associated with rigid kyphosis. Posterior surgery cannot restore cervical lordosis, and adequate decompression is not possible with rigid kyphosis. Vertebral body sliding osteotomy (VBSO) is a safe and novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. It is safe in terms of dural tear, pseudarthrosis, and graft dislodgement, which are demonstrated at high rates in anterior cervical corpectomy and fusion. In addition, VBSO is a powerful method for restoring cervical lordosis through multilevel anterior cervical discectomy and fusion above and below the osteotomy level. It may be a feasible treatment option for patients with cervical spondylotic myelopathy and kyphotic deformity. This is a technical note and literature review that describes the procedures involved in VBSO.

Segmental motion at the peak of the ossification foci is independent risk factor except for mal-alignment and thick ossification foci for poor outcome after laminoplasty for cervical ossification of the posterior longitudinal ligament: analyses in patients with positive K-line, lordotic alignment, and lower canal occupying ratio

PURPOSE

To elucidate the independent preoperative factors that have a significant impact on poor surgical outcome after laminoplasty for K-line (+) ossification of the posterior longitudinal ligament (OPLL). Analyses in K-line (+) patient population can exclude the influence by mal-alignment and thick OPLL, both of which are well known two major factors that have significant impact on clinical outcome.

METHODS

The present study included 72 patients (50 male and 22 female) who underwent laminoplasty for K-line (+) cervical OPLL and were followed-up for at least 1 year. Recovery of Japanese Orthopedic Association score (JOA score) for cervical myelopathy was used as the measure of clinical outcome. For radiographic assessment, the type of OPLL, the maximum OPLL occupation ratio, the C2-C7 angle, and the segmental range of motion at the peak of OPLL (segmental ROM) were assessed. To elucidate the factors that are significantly associated with a poor clinical outcome after laminoplasty for K-line (+) OPLL, statistical analyses were conducted.

RESULTS

The mean preoperative JOA score was 8.9 points and improved to 12.8 points after surgery. The recovery of JOA score was 47 ± 35%. Stepwise logistic regression following univariate analyses revealed that preoperative segmental ROM at the peak of OPLL is an independent factor associated with a poor outcome (p = 0.04, odds ratio = 1.15).

CONCLUSIONS

Large preoperative segmental ROM at the peak of the OPLL is an independent factor that has significant impact on poor surgical outcome after laminoplasty for K-line (+) OPLL.

The characteristics of the patients with radiologically severe cervical ossification of the posterior longitudinal ligament of the spine: A CT-based multicenter cross-sectional study

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.

Comparison of Anterior Controllable Antedisplacement and Fusion With Posterior Laminoplasty in the Treatment of Multilevel Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective, Randomized, and Control Study With at Least 1-Year Follow Up

STUDY DESIGN

A prospective, randomized, controlled study.

OBJECTIVE

To compare anterior controllable antidisplacement and fusion (ACAF) with laminoplasty in the treatment of multilevel ossification of the posterior longitudinal ligament (OPLL), and evaluate the efficacy and safety of this procedure.

SUMMARY OF BACKGROUND DATA

The optimal approach for the treatment of OPLL still remains controversial. Both anterior and posterior approaches have their advantages and disadvantages.

METHODS

Between September 2016 and April 2018, a total of 80 patients with multilevel OPLL were randomized in a 1:1 ratio to ACAF group and laminoplasty group. All patients were followed up at least 1 year. Clinical and radiological results were compared between ACAF group and laminoplasty group.

RESULTS

ACAF took a longer operation time. C5 palsy and axial pain occurred more commonly in laminoplasty group, whereas dysphagia and hoarseness appeared easily in ACAF group. At 1-year follow-up, the final Japanese Orthopedic Association (JOA) score and recovery rate were significant higher in ACAF group than those in laminoplasty group, when occupying rate (OR) was not less than 60%, or K-line was negative. ACAF was also good at preservation of cervical lordosis and sagittal balance, but range of movement of cervical spine in both groups decreased significantly.

CONCLUSION

Generally speaking, ACAF is a safe and effective alternative for multilevel OPLL. Compared with laminoplasty, ACAF is more effective in the cases when OR is not less than 60%, or K-line is negative.

LEVEL OF EVIDENCE

2.

Comparison of Perioperative Complications in Anterior Decompression With Fusion and Posterior Decompression With Fusion for Cervical Ossification of the Posterior Longitudinal Ligament: Propensity Score Matching Analysis Using a Nation-Wide Inpatient Database

STUDY DESIGN

A retrospective comparative study.

OBJECTIVE

To compare the perioperative complications and costs of anterior decompression with fusion (ADF) and posterior decompression with fusion (PDF) for patients with cervical ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

Surgical treatment of cervical OPLL has a high risk of various complications. ADF and PDF are effective for the treatment of cervical OPLL; however, few studies have compared the two procedures in terms of the perioperative surgical complications.

METHODS

Patients undergoing ADF and PDF for cervical OPLL from 2010 to 2016 were identified in a nation-wide inpatient database. We investigated systemic and local complications, length of hospital stay, costs for hospitalization, reoperation, and mortality. Propensity score was calculated from patients' characteristics and preoperative comorbidities, and one to one matching was performed.

RESULTS

Propensity score-matching produced 854 pairs of patients who underwent ADF and PDF. The rate of at least one systemic complication was significantly higher in the ADF group (P = 0.004). The incidence rates of postoperative respiratory failure (P = 0.034) and dysphagia (P = 0.008) were significantly higher in the ADF group. The rates of pneumonia (P = 0.06) and hoarseness (P = 0.08) also tended to be higher in the ADF group. However, no difference was found in the mortality rate (P = 0.22). In the local complications, spinal fluid leakage was significantly higher in the ADF group (P < 0.001). However, blood transfusion rate was significantly higher in the PDF group (P = 0.001). Hospital stay was significantly longer in the PDF group (P < 0.001) and the cost for hospitalization was greater in the PDF group (P < 0.001).

CONCLUSION

The present study demonstrated that perioperative complications, such as respiratory failure, dysphagia, and spinal fluid leakage, were more common in the ADF group. However, hospital stay was longer in the PDF group, and the cost for hospitalization was greater in the PDF group.

LEVEL OF EVIDENCE

3.

Transthoracic microsurgical anterior decompression without fusion for ossification of the posterior longitudinal ligament in the thoracic spine

OBJECTIVE

The authors aimed to analyze outcomes following transthoracic microsurgical anterior decompression of thoracic ossification of the posterior longitudinal ligament (T-OPLL), which was causing myelopathy, and determine the predictive factors for surgical outcomes.

METHODS

Patients who underwent transthoracic microsurgical anterior decompression without fusion for the treatment of T-OPLL from December 2014 to May 2019 were included. Demographic, radiological, and perioperative data and clinical outcomes of 35 patients were analyzed. The modified Japanese Orthopaedic Association (mJOA) score and recovery rate were used to evaluate functional outcomes.

RESULTS

A total of 35 consecutive patients (8 men and 27 women; mean age 52.2 ± 10.8 years) were enrolled in this study, and the mean follow-up period was 65.5 ± 51.9 months. The mean mJOA score significantly improved after surgery (5.9 ± 1.8 vs 8.3 ± 1.5, p < 0.001), with a mean recovery rate of 47.7% ± 24.5%. The visual analog scale (VAS) score significantly improved after surgery (7.3 ± 1.3 vs 4.3 ± 0.7, p < 0.001). The outcome was excellent in 4 patients (11.4%), good in 21 patients (60.0%), fair in 4 patients (11.4%), unchanged in 5 patients (14.3%), and worsened in 1 patient (2.9%). There were 12 cases of CSF leakage, 1 case of epidural hematoma, 1 case of pleural effusion, and 1 case of pneumothorax. Age, preoperative kyphotic angle, anteroposterior length of T-OPLL at the maximally affected level, and mass occupying rate were identified as predictors associated with postoperative outcome. A multivariate regression analysis revealed that age and preoperative kyphotic angle were independent risk factors for postoperative outcomes.

CONCLUSIONS

Transthoracic microsurgical anterior decompression without fusion achieved favorable clinical and radiological outcomes for treating T-OPLL with myelopathy. Patient age and preoperative kyphotic angle were independent risk factors for lower recovery rate.

Anterior selective stabilization combined with laminoplasty for cervical myelopathy due to massive ossification of the posterior longitudinal ligament: report of early outcomes in 14 patients

OBJECTIVE

Surgical management of massive ossification of the posterior longitudinal ligament (OPLL) is challenging. To reduce surgical complications, the authors have performed anterior selective stabilization combined with laminoplasty (antSS+LP) for massive OPLL since 2012. This study aimed to elucidate the short-term outcome of the antSS+LP procedure.

METHODS

The authors' analysis was based on data from 14 patients who underwent antSS+LP for cervical myelopathy caused by massive OPLL and were followed up for at least 2 years after surgery (mean follow-up duration 3.3 years). Clinical outcome was evaluated preoperatively, at 6 months and 1 year postoperatively, and at the final follow-up using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy and the recovery rate of the JOA score. The following radiographic parameters were measured preoperatively, immediately after surgery, at 1 year after surgery, and at the final follow-up: the C2-7 angle, measured on lateral plain radiographs, and the segmental lordosis angle (SLA), measured on sagittal CT scans. The correlation between radiographic parameters and clinical outcomes was evaluated.

RESULTS

The mean JOA score increased from 10.4 before surgery to 13.6 and 13.8 at 6 months and 1 year after surgery, respectively; at the final follow-up the mean score was 13.4. This postoperative recovery was significant (p = 0.004) and was maintained until the final follow-up. No patient required revision surgery due to postoperative neurological deterioration. However, the C2-7 angle gradually deteriorated postoperatively. Similarly, the SLA was significantly increased immediately after surgery, but the improvement was not maintained. The recovery rate at the final follow-up correlated positively with the change in C2-7 angle (r = 0.60, p = 0.03) and the change in SLA (r = 0.72, p < 0.01).

CONCLUSIONS

AntSS+LP is safe and effective and may be an alternative to anterior decompression and fusion for the treatment of patients with massive OPLL. No postoperative neurological complications or significant postoperative exacerbation of neck pain were observed in our case series. Not only reducing intervertebral motion and decompressing the canal at the maximal compression level but also acquiring segmental lordosis at the maximal compression level are crucial factors for achieving successful outcomes of antSS+LP.

Posterior decompression and fusion versus laminoplasty for cervical ossification of posterior longitudinal ligament: a systematic review and meta-analysis

Both posterior decompression and fusion (PDF) and laminoplasty (LAMP) have been used to treat cervical myelopathy due to multilevel ossification of posterior longitudinal ligament (OPLL). However, considerable controversy exists over the choice of the two surgical strategies. Thus, the aim of this study is to compare clinical outcomes of PDF and LAMP for treatment of cervical myelopathy due to multilevel OPLL. We searched PubMed, EMBASE and Cochrane Central Register of Controlled Trials database to identify relevant clinical studies compared with clinical outcomes of PDF and LAMP for cervical OPLL. The primary outcomes including Japanese Orthopaedic Association (JOA) score and recovery rate of JOA were evaluated, and the secondary outcomes involving visual analogue scale (VAS), cervical curvature, OPLL progression rate, complication rate, reoperation rate and surgical trauma were also evaluated using Stata software. A total of nine studies were included in the current study, involving 324 patients. The current study suggests that compared with LAMP, PDF achieves a lower OPLL progression rate, better postoperative cervical curvature and similar neurological improvement in the treatment of multilevel cervical OPLL. However, PDF has a higher complication rate, more surgical trauma and higher postoperative VAS than LAMP.

Novel Technique as a Revision Surgery for Failed Anterior Cervical Corpectomy and Fusion in the Treatment of Cervical Myelopathy Due to Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

This article aimed to introduce a novel technique, the "seesaw technique," for failed anterior cervical corpectomy and fusion (ACCF) in the treatment of cervical ossification of the posterior longitudinal ligament.

METHODS

A patient who underwent ACCF 12 years ago and suffered gradually deteriorating neurologic function was referred to our institution. Preoperative imaging showed residual ossified mass at C5/6 level, causing compression to his spinal cord. He patient was treated by the seesaw technique. The main surgical procedures include removal of the plate and screws, removal of the osteophytes and diskectomy of C4/5, resection of the anterior part of C5 vertebral body, establishment of a transverse hinge at C7 vertebral body, installation of cervical plate and hoisting tool, and antedisplacement of C5 vertebral body and titanium mesh. Images were investigated before and after the procedure. The Japanese Orthopaedic Association score was used to evaluate his neurologic function, and surgery-related complications were also analyzed.

RESULTS

The patient acquired significant improvement of his neurologic function 2 days after the surgery, and he could walk by himself without assistance. Postoperative images showed his spinal canal was enlarged sufficiently and the compression at C5/6 level was also released. At 13 months follow-up, his Japanese Orthopaedic Association score increased from 9 before surgery to 14, with an improvement rate of 62.5%. No surgery-related complications were observed during the whole follow-up.

CONCLUSION

The seesaw technique provides satisfactory outcomes with wide enough decompression window and serves as a safe, effective surgical alternative for patients with failed ACCF.

Surgical outcomes of cervical myelopathy due to ossification of posterior longitudinal ligament: Anterior decompression and fusion versus posterior laminoplasty

BACKGROUND

The purpose of this study was to compare the surgical outcomes of anterior decompression and fusion (ADF) with that of posterior laminoplasty (LAMP) for cervical myelopathy caused by ossification of posterior longitudinal ligament (OPLL).

METHODS

We retrospectively assessed the medical records of patients who underwent surgery for cervical myelopathy owing to OPLL between 2007 and 2016 at our institution. Fifty patients were included in this study, including 17 patients in ADF group and 33 patients in LAMP group. Surgical outcomes were assessed under the Japanese Orthopaedic Association (JOA) score. The radiologic and clinical data were compared between two groups.

RESULTS

There was no significant difference in age, follow-up time, operation time, blood loss, length of stay, preoperative JOA score, occupying ratio of OPLL, diameter of spinal canal, preoperative and final follow-up C2-C7 Cobb angles, and the change of C2-C7 Cobb angle before and after operation between ADF and LAMP groups. The final follow-up JOA score and the neurological recovery rate were significantly higher in ADF group than in LAMP group, particularly in patients with segmental-type OPLL. Cerebrospinal fluid leakage is a major complication after ADF, C5 paralysis, and axial pain frequently results from LAMP.

CONCLUSION

Compared with LAMP, ADF shows better improvement of neurological function in patients with cervical myelopathy due to OPLL, especially in patients with segmental-type cervical OPLL.

Safety and Efficacy of a Novel Anterior Decompression Technique for Ossification of Posterior Longitudinal Ligament of the Cervical Spine

INTRODUCTION

Anterior cervical corpectomy and fusion (ACCF) for cervical ossification of the posterior longitudinal ligament (OPLL) is associated with a high incidence of surgery-related complications. A novel anterior decompression technique (vertebral body sliding osteotomy [VBSO]) has been developed to prevent such complications. This study attests the efficacy and safety of VBSO versus those of standard ACCF.

METHODS

Patients requiring surgery for cervical OPLL underwent VBSO (24 patients) or ACCF (38 patients). Operating time, estimated blood loss, neurologic outcomes, complications, and various radiographic parameters were investigated.

RESULTS

The VBSO group showed a shorter mean operating time and less estimated blood loss versus the ACCF group. Sixteen patients in the ACCF group experienced various complications, namely neurologic deficit (two patients), cerebrospinal fluid leakage (four patients), graft migration (three patients), and pseudarthrosis (seven patients). In the VBSO group, only pseudarthrosis was reported (two patients).

CONCLUSIONS

VBSO provides similar neurologic outcomes with a shorter operating time and less bleeding compared with ACCF. Surgeons do not need to directly manipulate the OPLL mass or dissect the interspace between the OPLL and dura mater. Therefore, this technique may decrease the incidence of surgery-related complications.

STUDY DESIGN

Retrospective comparative study.

Clinical characteristics in patients with ossification of the posterior longitudinal ligament: A prospective multi-institutional cross-sectional study

Ossification of the posterior longitudinal ligament (OPLL) can occur throughout the entire spine and can sometimes lead to spinal disorder. Although patients with OPLL sometimes develop physical limitations because of pain, the characteristics of pain and effects on activities of daily living (ADL) have not been precisely evaluated in OPLL patients. Therefore, we conducted a multi-center prospective study to assess whether the symptoms of cervical OPLL are different from those of cervical spondylosis (CS). A total of 263 patients with a diagnosis of cervical OPLL and 50 patients with a diagnosis of CS were enrolled and provided self-reported outcomes, including responses to the Japanese Orthopaedic Association (JOA) Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), JOA Back Pain Evaluation Questionnaire (JOABPEQ), visual analog scale (VAS), and SF-36 scores. The severity of myelopathy was significantly correlated with each domain of the JOACMEQ and JOABPEQ. There was a negative correlation between the VAS score for each domain and the JOA score. There were significantly positive correlations between the JOA score and the Mental Health, Bodily Pain, Physical Functioning, Role Emotional, and Role Physical domains of the SF-36. One-to-one matching resulted in 50 pairs of patients with OPLL and CS. Although there was no significant between-group difference in scores in any of the domains of the JOACMEQ or JOABPEQ, the VAS scores for pain or numbness in the buttocks or limbs were significantly higher in the CS group; however, there was no marked difference in low back pain, chest tightness, or numbness below the chest between the two study groups. The scores for the Role Physical and Body Pain domains of the SF-36 were significantly higher in the OPLL group than in the CS group, and the mean scores for the other domains was similar between the two groups. The results of this study revealed that patients with OPLL were likely to have neck and low back pain and restriction in ADL. No specific type of pain was found in patients with OPLL when compared with those who had CS.

A novel anterior decompression technique for kyphosis line (K-line) ossification of posterior longitudinal ligament (OPLL): vertebral body sliding osteotomy

Background

Conventional anterior cervical corpectomy and fusion (ACCF) for cervical ossification of the posterior longitudinal ligament (OPLL) is associated with a high incidence of surgery-related complications. A novel anterior decompression technique [vertebral body sliding osteotomy (VBSO)] has been developed to prevent such complications and achieve effective anterior decompression for severe OPLL patients. The purpose of this study was to describe the procedure of novel surgical technique and to evaluate the long-term surgical outcomes.

Methods

Between 2012 and 2014, 24 patients underwent VBSO for treatment of cervical myelopathy caused by severe OPLL. Operation time, estimated blood loss (EBL), neurologic outcomes and perioperative complications were investigated. Various radiographic parameters such as the preoperative canal occupying ratio, postoperative canal widening, and preoperative and postoperative cervical sagittal alignment were also measured. Minimum follow-up was 24 months.

Results

The mean Japanese Orthopaedic Association score for cervical myelopathy (C-JOA score) improved from 12.4±2.9 preoperatively to 16.0±1.4 at the final follow-up (P<0.05). The mean recovery rate of the C-JOA score at the final follow-up was 68.65%±17.80%. The mean operating time was 130.7±21.0 minutes and the EBL was 176.3±38.0 mL. There were no perioperative complications. Pseudarthrosis was detected in two cases at 12 months postoperatively. The average spinal canal compromised ratio by OPLL decreased from 64.0%±15.0% preoperatively to 15.5%±12.2% postoperatively (P<0.05), with an average postoperative canal widening of 5.15±1.39 mm.

Conclusions

Novel anterior decompression technique termed VBSO may be an effective and safe surgical option for anterior decompression surgery in patients with severe cervical OPLL. Since, VBSO does not involve a direct manipulation of the OPLL mass or dissection of the interspace between the OPLL and dura mater, this may significantly decrease the incidence of surgery-related complications, operation time, and intraoperative blood loss.

A systematic review and meta-analysis comparing anterior decompression with fusion and posterior laminoplasty for cervical ossification of the posterior longitudinal ligament

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.

Long-term Outcome of Anterior Cervical Decompression With Fusion for Cervical Ossification of Posterior Longitudinal Ligament Including Postsurgical Remnant Ossified Spinal Lesion

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to assess the outcome, perioperative complications, and prognostic factors of anterior cervical decompression and fusion (ACDF) in patients with cervical ossification of posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

There is little information on the long-term surgical outcome of ACDF including postsurgical remnant ossified spinal lesion.

METHODS

Between 1993 and 2013, 80 patients with cervical myelopathy towing to OPLL underwent ACDF at our hospital. Among these, 42 patients were followed-up for at least 5 years and their data were analyzed.

RESULTS

The mean follow-up period was 7.9 ± 2.8 years, and the overall improvement rate was 59.2% ± 15.0%. Although 12 (15.0%) perioperative complications were observed in 6 patients, accompanied by neurological deterioration, none of the patients had chronic complications. Multivariate logistic regression analysis that included the preoperative Japanese Orthopaedic Association (JOA) score, type of OPLL, occupying ratio of OPLL, and number of fused segments and increase in the transverse area of the cord identified the latter parameter as the only independent and significant determinant of radiological and clinical improvement of >50%. Among the patients with remaining ossified spinal lesions out of the decompressed range (16 patients), postoperative progression was observed in 6 cases (14.3%) who were all of the mixed type; floated lesions within the decompressed range did not show progression during the follow-up. Adjacent segment degeneration was seen in nine (21.4%) patients, and neurological signs and symptoms were seen in only three of the nine patients and only one patient required revision surgery.

CONCLUSION

The long-term clinical outcome of patients with cervical OPLL after ACDF is considered satisfactory. Surgery-related complications and adjacent segment diseases should not be reasons to avoid ACDF. Care should be taken in selecting ACDF with postsurgical remnant ossified spinal lesion, as it could progress postoperatively especially in the mixed type OPLL.

LEVEL OF EVIDENCE

4.

Ossification of the Posterior Longitudinal Ligament: Surgical Approaches and Associated Complications

Ossification of the posterior longitudinal ligament (OPLL) is a rare but potentially devastating cause of degenerative cervical myelopathy (DCM). Decompressive surgery is the standard of care for OPLL and can be achieved through anterior, posterior, or combined approaches to the cervical spine. Surgical correction of OPLL via any approach is associated with higher rates of complications and the presence of OPLL is considered a significant risk factor for perioperative complications in DCM surgeries. Potential complications include dural tear (DT) and subsequent cerebrospinal fluid leak, C5 palsy, hematoma, hardware failure, surgical site infections, and other neurological deficits. Anterior approaches are technically more demanding and associated with higher rates of DT but offer greater access to ventral OPLL pathology. Posterior approaches are associated with lower rates of complications but may allow for continued disease progression. Therefore, the decision to pursue either an anterior or posterior approach to surgical decompression may be critically influenced by complications associated with each procedure. The authors critically review anterior and posterior approaches to surgical decompression of OPLL with particular focus on the complications associated with each approach. We also review the recent work in developing new surgical treatments for OPLL that aim to reduce complication incidence.

Does Ossification of the Posterior Longitudinal Ligament Progress After Fusion?

Starting in the 1960s, ossification of the posterior longitudinal ligament (OPLL) became more commonly diagnosed in Japan. The disease is characterized by a gradual increase in calcification of the posterior longitudinal ligament with the eventual sequelae of cervical canal stenosis and myelopathy. Surgical interventions to relieve stenosis and neurologic symptoms are performed to decompress the cervical canal. Studies demonstrate continued ossification of the OPLL in both nonsurgical and surgically treated patients. In this review, the authors evaluate the epidemiology, pathophysiology, and literature regarding disease progression in OPLL after cervical fusion.

The Clinical Implications and Complications of Anterior Versus Posterior Surgery for Multilevel Cervical Ossification of the Posterior Longitudinal Ligament; An Updated Systematic Review and Meta-Analysis

OBJECTIVE

Theoretically, the optimal approach is determined by the status of ossification of the posterior longitudinal ligament (OPLL) and sagittal alignment. However, there have long been disputes about the optimum surgical approach of OPLL. This study is to compare risk-effectiveness between anterior decompression and fusion (ADF) and laminoplasty and laminectomy with fusion (LP/LF) for the patient with cervical myelopathy due to multilevel cervical OPLL.

METHODS

We searched core databases, and compared complication and outcomes between ADF and LP/LF for patients with multiple OPLL for the cervical spine. The incidence of complications such as neurologic deterioration, C5 palsy, and dura tear was assessed. Changes in JOA score between baseline and final evaluations were assessed for 2 groups. The minimal clinically important difference (MCID) was utilized for evaluating clinical significance. We calculated Peto odds ratio (POR) and mean difference for the incidence and continuous variables, respectively.

RESULTS

We included data from 21 articles involving 3,872 patients with cervical myelopathy with OPLL. Major neurologic deficits such as paraplegia, quadriplegia developed 2.17% in the ADF group and 1.11% in the LP/LF group, and POR was 2.16. Mean difference of JOA score improvement of 2 groups was 1.30, and the mean difference showed a statistical significance. However, 1.3 points of JOA improvement cannot reach 2.5 points of the MCID.

CONCLUSION

Anterior surgery often led to rare but critical complications, and the difference of neurological improvement between 2 groups was below a clinically meaningful level. Posterior surgeries may be appropriate in the treatment of multilevel cervical myelopathy with OPLL.

Ossification of Posterior Longitudinal Ligament of Cervical Spine Among Omani Patients Referred for CT Scan at a Tertiary Care Hospital in Oman

Objectives

We sought to evaluate the proportion of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine and associated factors among Omani patients.

Methods

We reviewed the cervical spine computed tomography (CT) scans of all patients referred to the Radiology Department, Sultan Qaboos University Hospital, from 2011 to 2017. Descriptive statistics were employed to determine the proportion of OPLL. We used the chi-square test to determine the association of age, gender, and diabetes mellitus with OPLL.

Results

A total of 843 patients aged ≥ 20 years were included in the study. The proportion of OPLL was 2.7% and was more frequent in men (3.2%) than women (1.9%). The male to female ratio of OPLL was 1.7:1.0. OPLL occurrence was significantly more in non-diabetic patients (p < 0.001). No significant association was found between OPLL with gender (p = 0.281) and age (p = 0.878).

Conclusions

The observed proportion of OPLL in this single-center study is relatively low, but the finding is important as the condition can eventually lead to debilitating neurologic outcomes affecting the patient's quality of life. OPLL occurrence was significantly more in non-diabetic patients, which necessitate further research on OPLL in a larger sample across Oman.

To Determine the Surgical Outcome of Anterior Cervical Corpectomy and Fusion without Fixation for Ossification of Posterior Longitudinal Ligament

Aims:

The purpose of our study is to evaluate the surgical outcome in patients undergoing anterior cervical corpectomy without fixation with plates and screws for the treatment of ossification of posterior longitudinal ligament (OPLL).

Subjects and Methods:

The type of study was case series and was conducted from January 2015 to December 2015 for 1-year duration at the Department of Neurosurgery at a Tertiary Care hospital in Karachi, Pakistan. A total of n = 20 patients (16 men and 4 women; mean age of 57.45 ± 6.4 years [range: 45–68 years]) were included after thorough clinical history and physical examination. Neurological evaluation was done using the Japanese Orthopedic Association (JOA) scoring system. The pre- and post-operative JOA scores were used to calculate recovery rate (RR) of the patients. Radiographic assessment was done using various modalities such as X-ray, computed tomography scan, and magnetic resonance imaging. Surgical outcome and complications were studied and the data were analyzed using SPSS 21.

Results:

After the uniform follow-up period of 12 months, mean JOA scores improved from 9.1 ± 1.37 preoperatively to 14.3 ± 1.69 postoperatively and mean RR was 67.01 ± 15.5%. All the patients showed successful osseous fusion while one patient did not. Two patients developed cerebrospinal fluid leakage, one patient developed recurrent laryngeal nerve palsy, and one expired due to iatrogenic neurological deterioration.

Conclusion:

Anterior cervical corpectomy without fixation with plates and screws is an effective surgical procedure for the treatment of OPLL (for up to three cervical levels of OPLL). It gives good neurological recovery with fewer postoperative complications.

Extended Laminoplasty for Ossification of Posterior Longitudinal Ligament Involving the C2 Segment

BACKGROUND

To evaluate effectiveness and safety of extended laminoplasty for the treatment of ossification of posterior longitudinal ligament (OPLL) involving the C2 segment.

METHODS

A total of 132 cases who accepted laminoplasty for treating the OPLL from 2010 to 2015 were included and divided into Group A (n = 26, with C2 OPLL and C2-C7 laminoplasty), Group B (n = 29, with C2 OPLL and C3-C7 laminoplasty), and Group C (n = 77, without C2 OPLL and had C3-C7 laminoplasty). Clinical and radiologic outcomes were compared among the 3 groups.

RESULTS

At the final visit, significant improvements in Japanese Orthopedic Association score, Neck Disability Index, Health-Related Quality-of-Life Short Form 36 Physical Component Summary, and Visual Analog Scale score in neck were observed in all 3 groups. However, all the C2-C7 Cobb angle, C2-C3 Cobb angle, sagittal vertical axis, and number of cases with cervical or segmental kyphosis in the 3 groups were not significantly changed. Although total blood loss, operation time, maximum Visual Analog Scale score in neck, incidence of axial pain, change of C2-C7, or sagittal vertical axis in Group A were all significantly larger than that in Group B or Group C, differences in neurologic recovery rate, Neck Disability Index, Health-Related Quality-of-Life Short Form 36 Physical Component Summary, change of the C2-C3 Cobb angle, and incidence of cervical or segmental malalignment among the 3 groups were not significant at the final visit.

CONCLUSIONS

If decompression indication for cases with OPLL involving the C2 segment was appropriate, extended laminoplasty up to the C2 segment could provide satisfactory neurologic recovery and would not accelerate cervical or segmental malalignment progression.

Development and Achievement of Cervical Laminoplasty and Related Studies on Cervical Myelopathy

Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.

Indication for anterior spinal cord decompression via a posterolateral approach for the treatment of ossification of the posterior longitudinal ligament in the thoracic spine: a prospective cohort study

PURPOSE

For ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine, anterior decompression is the most effective method for relieving spinal cord compression. The purpose of this study was to prospectively analyze the surgical outcomes based on our strategy in the treatment of thoracic OPLL.

METHODS

This study included 23 patients who underwent surgery for thoracic OPLL based on the following strategy between 2011 and 2017. For patients with a beak-type OPLL in the kyphotic curve with a ≥ 50% canal occupying ratio, circumferential decompression via a posterolateral approach and fusion (CDF) was indicated. For other types of OPLL, posterior decompression and fusion (PDF) was commonly indicated. Posterior fusion without decompression (PF) was applied when the spinal cord was separated from the posterior spinal elements. Clinical and radiological outcomes were compared among the CDF, PDF, and PF groups with a minimum of 20-month follow-up.

RESULTS

Ten, eleven, and two patients underwent CDF, PDF, and PF, respectively. The preoperative Japanese Orthopedic Association (JOA) score in the CDF group was significantly lower than that in the PDF group. The average recovery rate, according to JOA score, was 63%, 56%, and 25% in the CDF, PDF, and PF groups, respectively. The result in the CDF group was better than that in the PF group.

CONCLUSIONS

Anterior decompression was appropriate for patients with localized spinal cord compression by a large OPLL in the kyphotic curve, and CDF via a posterolateral approach appears to be safe and effective. These slides can be retrieved under Electronic Supplementary Material.

Analyses of effect factors associated with the postoperative dissatisfaction of patients undergoing open-door laminoplasty for cervical OPLL: a retrospective cohort study

Objectives

This study aimed to investigate the effect factors associated with the postoperative dissatisfaction of patients undergoing open-door laminoplasty for cervical OPLL.

Methods

In this study, 194 patients, who underwent open-door laminoplasty for cervical OPLL from January 2009 to January 2016, were retrospectively reviewed. The Patient Satisfaction Index (PSI) was collected at discharge, 6 months, 1 year, and the last follow-up. According to the PSI, patients were divided into satisfied group and dissatisfied group. The possible effect factors included demographic variables and surgery-related variables.

Results

At discharge, 42 (21.6%) patients were in the dissatisfied group, as compared to the satisfied group, the hospitalization cost, hospital stay, postoperative depression, the axial neck pain, delayed wound healing, and VAS-neck had significant statistical differences. At 6-month follow-up, 25 (12.9%) patients were in the dissatisfied group. The axial neck pain and JOA score had significant statistical differences between the two groups, and no significant differences were found between the two groups in other items. At 1 year with 18 (9.3%) dissatisfied patients and last follow-up with 14 (7.2%) dissatisfied patients, the JOA score and symptom recurrence had significant statistical differences. For further analysis, the dissatisfied patients with axial neck pain at 6 months were significantly higher than that at other terms and the JOA score of the two groups increased gradually with prolonging of restoration years but compared with the dissatisfied group, the JOA scores were obviously better in the satisfied group at the last follow-up.

Conclusions

Overall, to patients undergoing open-door laminoplasty for cervical OPLL, hospitalization cost and neck pain might be mainly associated with patient dissatisfaction at the early and middle recovery. Patient dissatisfaction at the long-term treatment outcome might be mainly associated with the low improvement rate of JOA score and symptom recurrence.

Anterior Cervical Corpectomy and Fusion Versus Posterior Laminoplasty for Cervical Oppressive Myelopathy Secondary to Ossification of the Posterior Longitudinal Ligament: A Meta-analysis

The purpose of this study was to compare the clinical effect of anterior cervical corpectomy with fusion vs laminoplasty for cervical ossification of the posterior longitudinal ligament. The outcome measures included the Japanese Orthopaedic Association score, neurological recovery rate, and complication rate. Subgroup A represented studies with the mean preoperative canal occupying ratio being less than 50%, whereas subgroup B represented studies with the mean canal occupying ratio being 50% or greater. In subgroup A, no difference was found between the 2 groups in the postoperative Japanese Orthopaedic Association score and neurological recovery rate. In subgroup B, the anterior cervical corpectomy with fusion group had a higher postoperative Japanese Orthopaedic Association score and neurological recovery rate. The authors recommend anterior cervical corpectomy with fusion for cervical ossification of the posterior longitudinal ligament when the canal occupying ratio is 50% or greater, and they prefer laminoplasty when the canal occupying ratio is less than 50%. [Orthopedics. 2019; 42(3):e309-e316.].

Effectiveness of titanium plate usage in laminoplasty

Background:

Laminoplasty is an established technique for the treatment of cervical stenosis. However, the usage of plates to maintain patency of the laminoplasty door has not been well reported. This study plans to compare the clinical outcomes of laminoplasty with the usage of Sofamor-Danek laminoplasty plates versus techniques without plate usage.

Materials and Methods:

This study conducted a 2-year medical record review of all patients with multilevel cervical myelopathy who were treated with laminoplasty at UCLA or Cedars-Sinai medical center. Of 46 patients 18 had sufficient documentation to assess clinical outcome, 11 of which had placement of laminoplasty plates. Clinical outcomes were assessed using Odom's scoring criteria.

Results:

Blood loss and hospital stay are decreased with plate usage during laminoplasty. Average Estimated Blood Loss (EBL) was 160 cc with plate and 380 cc without. Hospital stay was 4.8 days with plate and 5.6 days without. There were no complications during any of the laminoplasty procedures regardless of instrumentation. All patients demonstrated improvement in symptoms after laminoplasty, with 73% of patients in the plate cohort having Odom Scores of “Excellent” versus 44% in the nonplate group. All patients, regardless of technique, showed improvement in symptoms.

Conclusions:

Laminoplasty with plate utilization is an effective treatment for cervical myelopathy. The similarity in outcomes and complications between these two similar cohorts suggests plate usage in laminoplasty is an attractive alternative to other methods. We hope that future efforts will continue to demonstrate the effectiveness and perhaps superiority of plate utilization in laminoplasty.

Postoperative Progression of Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review

OBJECTIVE

The purpose of this study was to provide a systematic and comprehensive review of the existing literature regrading postoperative ossification of posterior longitudinal ligament (OPLL) progression.

METHODS

Using the PRISMA guidelines, we conducted an exhaustive review of electronic databases. Potential articles were screened and related information was extracted and analyzed. Twenty-four articles with low-quality evidence were included in the review. The findings of the literature review were divided into several groups: the relationship of surgery to OPLL progression; incidence and risk factors; timing and process of OPLL progression; the effect of additional instrumentation on progression; and neurologic deterioration related with progression.

RESULTS

There was no definitive conclusion for whether surgery could accelerate OPLL progression compared with the natural course. The incidence of postoperative OPLL progression was reported from 3.3% to 74.5%. Younger age, involvement of multiple levels and mixed or continuous types are recognized as risk factors. OPLL could progress transversely and longitudinally and progression in length appeared more significant than progression in thickness. Although radiologic OPLL progression was observed significantly more frequently after laminoplasty than after fusion surgery, whether additional instrumented fusion could suppress progression needs further research. Radiographic progression of OPLL did not positively correspond with neurologic deterioration.

CONCLUSIONS

The lack of high-level evidence makes it difficult to draw definite conclusions and further research and long-term follow-up clinical studies are needed to better understand postoperative OPLL progression.

Perioperative complications of anterior decompression with fusion versus laminoplasty for the treatment of cervical ossification of the posterior longitudinal ligament: propensity score matching analysis using a nation-wide inpatient database

BACKGROUND CONTEXT

Surgical treatment of cervical ossification of the posterior longitudinal ligament (OPLL) has a high risk of various complications. Anterior decompression with fusion (ADF) and laminoplasty (LAMP) are the most representative surgical procedures. However, few studies have compared the two procedures in terms of perioperative surgical complications.

PURPOSE

To compare the perioperative complications post-ADF and LAMP for cervical OPLL using a large national inpatient database.

STUDY DESIGN

A retrospective cohort study with propensity score matching analysis.

PATIENT SAMPLE

Overall, 8,718 (ADF/LAMP:1,333/7,485) patients who underwent surgery for cervical OPLL from April 1, 2010 to March 31, 2016 in hospitals using the diagnosis procedure combination were analyzed.

OUTCOME MEASURES

The occurrence of postoperative complications during hospitalization.

METHODS

We compared the perioperative systemic and local complications, reoperation rates, and costs between ADF and LAMP using propensity score matching analysis.

RESULTS

One-to-one matching resulted in 1,192 pairs of patients who underwent ADF and LAMP. The postoperative cardiovascular event rate was significantly higher (ADF/LAMP=1.9/0.8%, p=.013) in the ADF group. The incidence rates of dysphagia (similarly, 2.4/0.2%, p<.001), pneumonia (1.0/0.3%, p=.045), and spinal fluid leakage (2.4/0.4%, p<.001) were also higher in the ADF group, even after matching. The costs were also higher in the ADF group. However, surgical site infection (2.0/3.4%, p=.033) was significantly lower in the ADF group. No significant difference in the reoperation rates was found between the groups.

CONCLUSION

The present study, using a large nationwide database, demonstrated that perioperative complications were more common in the ADF group, but that surgical site infection (SSI) was more frequently observed in the LAMP group.

A Systematic Review of Classification Systems for Cervical Ossification of the Posterior Longitudinal Ligament

DESIGN

Systematic review.

OBJECTIVE

To conduct a systematic review to (1) summarize various classification systems used to describe cervical ossification of the posterior longitudinal ligament (OPLL) and (2) evaluate the diagnostic accuracy of various imaging modalities and the reliability of these classification systems.

METHODS

A search was performed to identify studies that used a classification system to categorize patients with OPLL. Furthermore, studies were included if they reported the diagnostic accuracy of various imaging modalities or the reliability of a classification system.

RESULTS

A total of 167 studies were deemed relevant. Five classification systems were developed based on X-ray: the 9-classification system (0.60%); continuous, segmental, mixed, localized or focal, circumscribed and others (92.81%); hook, staple, bridge, and total types (2.40%); distribution of OPLL (2.40%); and K-line classification (4.19%). Six methods were based on computed tomography scans: free-type, contiguous-type, and broken sign (0.60%); hill-, plateau-, square-, mushroom-, irregular-, or round-shaped (5.99%); rectangular, oval, triangular, or pedunculate (1.20%); centralized or laterally deviated (1.80%); plank-, spindle-, or rod-shaped (0.60%); and rule of nine (0.60%). Classification systems based on 3-dimensional computed tomography were bridging and nonbridging (1.20%) and flat, irregular, and localized (0.60%). A single classification system was based on magnetic resonance imaging: triangular, teardrop, or boomerang. Finally, a variation of methods was used to classify OPLL associated with the dura mater (4.19%).

CONCLUSIONS

The most common method of classification was that proposed by the Japanese Ministry of Health, Labour and Welfare. Other important methods include K-line (+/-), signs of dural ossification, and patterns of distribution.

Patterns of short-term and long-term surgical outcomes and prognostic factors for cervical ossification of the posterior longitudinal ligament between anterior cervical corpectomy and fusion and posterior laminoplasty

To compare short-term and long-term surgical outcome patterns between anterior cervical corpectomy and fusion (ACCF) and laminoplasty (LP) in patients diagnosed with cervical ossification of the posterior longitudinal ligament (OPLL) and identify factors affecting surgical outcomes based on follow-up duration. During short-term follow-up period, surgical outcomes between ACCF and LP were similar. However, there were several reports that long-term surgical outcomes were superior in the ACCF compared with LP. Surgical outcomes between ACCF and LP according to follow-up period changed. This study enrolled 70 patients who underwent ACCF and 63 patients who underwent LP between 2005 and 2012. Patterns of surgical outcomes were analyzed in accordance with surgical procedures. Furthermore, these patients were divided into two subgroups in respect of follow-up duration: the short-term group (less than 48 months) and the long-term group (more than 48 months) group. Occupying ratio, type of OPLL, shape of ossified lesion, cervical sagittal alignment, grade of signal intensity on MRI, and Japanese Orthopedic Association (JOA) score were examined. Surgical outcomes of ACCF went into reverse at 48-month follow-up period. In the short-term group, JOA recovery rate had no difference between ACCF and LP. In the long-term group, the ACCF recovery rate (78.5 ± 31.0) was significantly higher than the LP recovery rate (48.4 ± 54.9) (P = 0.008). In the short-term group, old age (p = 0.011), hill shape (p = 0.013), and high grade of MRI signal intensity (p = 0.040) had negative effects on recovery rate. On the other hand, in the long-term group, LP (p = 0.021) and a high grade of MR signal intensity (p = 0.017) independently and negatively affected recovery rate. Long-term surgical outcomes of ACCF became better than those of LP at more than 48-month follow-up period. High-grade MRI signal changes and the LP surgical procedure were independent negative factors for long-term surgical outcomes in patients with OPLL. Direct decompression of the spinal cord with ACCF provides better long-term stable neurologic outcomes than LP.

Anterior decompression and fusion versus laminoplasty for cervical myelopathy due to ossification of posterior longitudinal ligament: A meta-analysis

BACKGROUND

Both anterior decompression and fusion (ADF) and laminoplasty (LAMP) are frequently used for the treatment of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). However, some controversies still remained in surgical options. We investigated whether ADF had better neurological outcome than LAMP in the treatment of cervical myelopathy due to OPLL. Secondary outcomes included operation time, blood loss, rate of complication and reoperation.

METHODS

PubMed, EMBASE and the Cochrane Register of Controlled Trials database were searched to identify potential clinical studies compared ADF with LAMP for treatment of cervical myelopathy owing to OPLL. We also manually searched the reference lists of articles and reviews for possible relevant studies. Quality assessment was performed according to Cochrane Handbook and meta-analysis was conducted using Stata 12.0 software.

RESULTS

Nine studies involving 712 patients were finally included in this analysis. Compared with LAMP, ADF was associated with an increase of the Japanese Orthopaedic Association (JOA) score (WMD = 1.86, 95% CI 0.43 to 3.29, P = .011) and recovery JOA score at final follow-up (WMD = 30.94, 95% CI 20.56 to 41.33, P = .000). And, ADF was associated with a decrease of the late neurologic deterioration than LAMP group (RR = 0.34, 95% CI 0.12 to 0.92, P = .003). However, ADF was associated with an increase of the postoperative cervical lordosis (WMD = 4.47, 95% CI 1.58 to 7.36, P = .002) than LAMP. There was no significant difference between the complication, reoperation rate (P > .05). What's more, ADF was associated with an increase of the operation time than LAMP (P < .05).

CONCLUSIONS

ADF yields better neurological improvement, but higher cervical lordosis and longer operation time compared with LAMP for cervical myelopathy caused by OPLL. No significant difference was found in the complication and re-operation rate.

A novel revision surgery for treatment of cervical ossification of the posterior longitudinal ligament after initial posterior surgery: preliminary clinical investigation of anterior controllable antidisplacement and fusion

BACKGROUND

Cervical ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. Posterior decompression surgery is reported to be an effective and comparatively safe procedure with few complications for treatment of patients with myelopathy caused by OPLL. However, some patients require revision surgery because of late neurological deterioration due to OPLL progression or kyphotic changes in cervical alignment. This study reports preliminary clinical results of anterior controllable antidisplacement and fusion (ACAF), a novel revision surgery after initial posterior surgery for OPLL.

METHODS

From January 2017 to June 2018, ten patients with cervical OPLL who underwent ACAF revision surgery after initial posterior surgery were included in this study. The mean age was 62.1 ± 8.0 years (52-78), and the mean interval between initial posterior surgery and revision was 78.0 ± 48.2 months (5-180). The Japanese Orthopaedic Association (JOA) scales, Neck Disability Index (NDI), visual analog scale (VAS), and surgical complications were recorded.

RESULTS

The mean surgery time was 179.3 ± 41.8 min (120-240), and the mean blood loss was 432.5 ± 198.3 ml (225-850). The patients were followed up for at least 12 months. The JOA scores improved from 8.7 ± 2.8 to 13.4 ± 2.4; the mean improvement rate was 59.9% ± 16.1%. Postoperative NDI and VAS scores were 13.3 ± 3.7 and 2.0 ± 1.6, respectively, and were significantly improved compared to those before the procedure (P < 0.05). Cervical lordosis improved from 3.8 ± 4.3° to 17 ± 4.6° after revision surgery. There was only one instance of cerebrospinal fluid (CSF) leakage; no instances of postoperative hematoma, C5 root palsy, or hoarseness occurred.

CONCLUSIONS

The present study demonstrates that excellent postoperative outcomes can be achieved with the ACAF technique for revision treatment of OPLL. Though further study is required to confirm the conclusion, this novel technique has the potential to serve as an alternative surgical technique for revision treatment of OPLL.

Ossification of the posterior longitudinal ligament in the cervical spine: a review

Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

Radiological risk factors for progression of ossification of posterior longitudinal ligament following laminoplasty

BACKGROUND CONTEXT

Research shows the progression of ossification of the posterior longitudinal ligament (OPLL) following decompressive surgery for cervical myelopathy, particularly in cases presenting with continuous or mixed radiographic types. To date, no study has investigated OPLL progression within each motion segment.

PURPOSE

To evaluate progression of cervical OPLL in each motion segment using a novel system of classification, and to identify risk factors for OPLL progression following laminoplasty.

STUDY DESIGN/SETTING

Retrospective case series.

PATIENT SAMPLE

This study included 34 patients (86 segments) with cervical myelopathy secondary to OPLL.

OUTCOME MEASURES

Clinical and radiological data (plain radiographs and computed tomography [CT]) were obtained.

METHODS

Clinical data from 34 patients (86 segments) with cervical myelopathy secondary to OPLL were evaluated retrospectively. All subjects had undergone laminoplasty at a single center. Sagittal reconstructive CT images were used to measure OPLL thickness in each segment. Ossified masses were classified into four types according to the degree of disc space involvement: type 1 (no involvement); type 2 (involving disc space but not crossing); type 3 (crossing disc space but not fused); and type 4 (complete bridging). Range of motion (ROM) for each segment was measured using dynamic radiographs. Statistical analyses were performed to determine the degree of OPLL progression according to the four disc space involvement types and ROM.

RESULTS

Mean OPLL progression was significantly higher in types 2 (1.3 mm) and 3 (1.5 mm) than in type 1 (0.5 mm) (p<.001). Severe progression (change in thickness >2 mm) was more frequent in types 2 (8 of 29) and 3 (7 of 16) than in types 1 (1 of 35) or 4 (0 of 6) (p=.002). In types 2 or 3, ROM>5° was correlated with severe OPLL progression (52% vs. 8%; p=.035).

CONCLUSIONS

Type 2 or 3 disc involvement and segmental ROM>5° were risk factors for OPLL progression. Classification of cervical OPLL according to disc involvement may help predict OPLL progression following laminoplasty. Close follow-up is warranted in cases of type 2 or 3 with greater segmental motion.

The K-line in the cervical ossification of the posterior longitudinal ligament is different on plain radiographs and CT images

BACKGROUND

The K-line, which is a virtual line between the midpoints of the antero-posterior canal diameter at C2 and C7, can be useful for determination of surgical procedures for cervical ossification of the posterior longitudinal ligament (OPLL). Although K-line is originally measured with plain radiogram, computed tomography multiplanar reconstruction (CT-MPR) is applied for K-line measurement by several surgeons. The purpose of the present study was to analyze whether there is a difference in K-lines obtained from radiographs of standing patients and those obtained from CT-MPR images of supine patients.

METHODS

The present study included 65 patients with cervical OPLL underwent surgical treatment. We investigated the K-line (+ or -) before surgery, measured from lateral cervical spine radiographs taken in standing patients in a neutral position (X-P-based K-line) and CT-MPR mid-sagittal images obtained in supine patients (CT-based K-line). The X-P-based and CT-based K-lines were compared and differences between them were assessed.

RESULTS

The-X-P-based K-line was found to be (+) in 35 patients and (-) in 30 patients. Four of 35 patients with an X-P-based K-line (11%) showed a change from K-line (+) to (-) in CT-based K-line measurements. One of 30 patients with an X-P-based K-line (3%) showed a change from (-) to (+) in CT-based measurements.

CONCLUSIONS

The K-line should be measured with plain radiogram of standing patients because X-P-based K-line and CT-based K-line can be different.

A novel anterior decompression technique (vertebral body sliding osteotomy) for ossification of posterior longitudinal ligament of the cervical spine

BACKGROUND CONTEXT

Conventional anterior decompression surgery for cervical myelopathy, including anterior corpectomy and fusion, is technically demanding and is known to be associated with a higher incidence of surgery-related complications, including cerebrospinal fluid (CSF) leakage, neurologic deterioration, and graft failure compared with posterior surgery.

PURPOSE

We introduce a novel anterior decompression technique (vertebral body sliding osteotomy [VBSO]) for cervical myelopathy caused by ossification of posterior longitudinal ligament (OPLL) and evaluate the efficacy and safety of this procedure.

STUDY DESIGN

This is a case series for novel surgical technique.

PATIENT SAMPLE

Fourteen patients (M:F=11:3, mean age 56.9±10) with cervical myelopathy caused by OPLL who underwent VBSO by a single surgeon were included.

OUTCOME MEASURES

The surgical outcome was evaluated according to the Japanese Orthopaedic Association score for cervical myelopathy (C-JOA score), and the recovery rate of the C-JOA score was calculated. Patients were also evaluated radiographically with plain and dynamic cervical spine radiographs and pre- and postoperative computed tomography images.

METHODS

Fourteen patients were followed up for more than 24 months, and operation time, estimated blood loss, neurologic outcomes, and surgery-related complications were investigated. Radiological measurements were also performed to analyze the following parameters: (1) canal-occupying ratio and postoperative canal widening, and (2) pre- and postoperative sagittal alignment.

RESULTS

The mean recovery rate of C-JOA score at the final follow-up was 68.65±17.8%. There were no perioperative complications, including neurologic deterioration, vertebral artery injury, esophageal injury, graft dislodgement, and CSF leaks, after surgery except for pseudarthrosis in one case. An average spinal canal compromised ratio by OPLL decreased from 61.5±8.1% preoperatively to 16.5±11.2% postoperatively. An average postoperative canal widening was 5.15±1.39 mm, and improvement of cervical alignment was observed in all patients, with average recovery angle of 7.3±6.1° postoperatively.

CONCLUSIONS

The VBSO allows sufficient decompression of spinal cord and provides excellent neurologic outcomes. Because surgeons do not need to manipulate the OPLL mass directly, this technique could significantly decrease surgery-related complications. Furthermore, as VBSO is based on the multilevel discectomy and fusion technique, it would be more helpful to restore a physiological lordosis.

Distribution of ossified spinal lesions in patients with severe ossification of the posterior longitudinal ligament and prediction of ossification at each segment based on the cervical OP index classification: a multicenter study (JOSL CT study)

Background

In patients with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine, it is well known that the thoracic ossified lesions often coexist with the cervical lesions and can cause severe myelopathy. However, the prevalence of OPLL at each level of the thoracic and lumbar spinal segments is unknown. The aims of this study were to investigate how often OPLL occurs at each level in the thoracolumbar spine in patients with a radiological diagnosis of cervical OPLL and to identify the spinal levels most likely to develop ossification.

Methods

Data were collected from 20 institutions in Japan. Three hundred and twenty-two patients with a diagnosis of cervical OPLL were included. The OPLL index (OP index), defined as the sum of the vertebral body and intervertebral disc levels where OPLL is present, was used to determine disease severity. An OP index ≥20 was defined as severe OPLL. The prevalence of OPLL at each level of the thoracic and lumbar spinal segments was calculated.

Results

Women were more likely to have ossified lesions in the thoracolumbar spine than men. Severe OPLL was significantly more common in women than in men (20% vs. 4.5%). For thoracic vertebral OPLL, the most frequently affected was the T1 segment in both men and women, followed by the T1/2 and T3/4 intervertebral levels in men and women, respectively. Ossified lesions were frequently seen at the intervertebral and vertebral levels around the cervicothoracic and thoracolumbar junctions in men with severe OPLL, whereas OPLL was more diffusely distributed in the thoracic spine in women with severe OPLL.

Conclusion

Thoracolumbar OPLL occurred most often at T1 in men and at T3/4 in women. In severe OPLL cases, although ossified lesions were frequently seen at the intervertebral and vertebral levels around the cervicothoracic and thoracolumbar junctions in men, OPLL could be observed more diffusely in the thoracic spine in women.

Geographic variations in clinical presentation and outcomes of decompressive surgery in patients with symptomatic degenerative cervical myelopathy: analysis of a prospective, international multicenter cohort study of 757 patients

BACKGROUND CONTEXT

Degenerative cervical myelopathy (DCM) is a progressive degenerative spine disease and the most common cause of spinal cord impairment in adults worldwide. Few studies have reported on regional variations in demographics, clinical presentation, disease causation, and surgical effectiveness.

PURPOSE

The objective of this study was to evaluate differences in demographics, causative pathology, management strategies, surgical outcomes, length of hospital stay, and complications across four geographic regions.

STUDY DESIGN/SETTING

This is a multicenter international prospective cohort study.

PATIENT SAMPLE

This study includes a total of 757 symptomatic patients with DCM undergoing surgical decompression of the cervical spine.

OUTCOME MEASURES

The outcome measures are the Neck Disability Index (NDI), the Short Form 36 version 2 (SF-36v2), the modified Japanese Orthopaedic Association (mJOA) scale, and the Nurick grade.

MATERIALS AND METHODS

The baseline characteristics, disease causation, surgical approaches, and outcomes at 12 and 24 months were compared among four regions: Europe, Asia Pacific, Latin America, and North America.

RESULTS

Patients from Europe and North America were, on average, older than those from Latin America and Asia Pacific (p=.0055). Patients from Latin America had a significantly longer duration of symptoms than those from the other three regions (p<.0001). The most frequent causes of myelopathy were spondylosis and disc herniation. Ossification of the posterior longitudinal ligament was most prevalent in Asia Pacific (35.33%) and in Europe (31.75%), and hypertrophy of the ligamentum flavum was most prevalent in Latin America (61.25%). Surgical approaches varied by region; the majority of cases in Europe (71.43%), Asia Pacific (60.67%), and North America (59.10%) were managed anteriorly, whereas the posterior approach was more common in Latin America (66.25%). At the 24-month follow-up, patients from North America and Asia Pacific exhibited greater improvements in mJOA and Nurick scores than those from Europe and Latin America. Patients from Asia Pacific and Latin America demonstrated the most improvement on the NDI and SF-36v2 PCS. The longest duration of hospital stay was in Asia Pacific (14.16 days), and the highest rate of complications (34.9%) was reported in Europe.

CONCLUSIONS

Regional differences in demographics, causation, and surgical approaches are significant for patients with DCM. Despite these variations, surgical decompression for DCM appears effective in all regions. Observed differences in the extent of postoperative improvements among the regions should encourage the standardization of care across centers and the development of international guidelines for the management of DCM.

Cervical Kyphotic Deformity after Laminoplasty in Patients with Cervical Ossification of Posterior Longitudinal Ligament with Normal Sagittal Spinal Alignment

Background

Preoperative cervico-thoracic kyphosis and cervical regional positive imbalance are the risk factors for postoperative cervical kyphosis after expansive laminoplasty (ELAP). However, the relationship between preoperative global sagittal spinal alignment and postoperative cervical kyphosis in patients with cervical ossification of the posterior longitudinal ligament (OPLL) is unclear. The purpose of this study was to investigate the relationship between the onset of postoperative cervical kyphosis after ELAP and the preoperative global spinal sagittal alignment in patients with OPLL with normal sagittal spinal alignment.

Methods

Sixty-nine consecutive patients without preoperative cervical kyphosis who underwent ELAP for OPLL and cervical spondylotic myelopathy (CSM) were enrolled. The global sagittal alignment radiography preoperatively and 1 year postoperatively were examined. The subjects were divided into a postoperative cervical lordosis group (LG) or a kyphosis group (KG) at 1 year postoperatively. The preoperative global sagittal spinal alignment between LG and KG in CSM and OPLL was compared.

Results

The occurrence of cervical kyphosis after ELAP was 7 of 27 cases (25.9%) in OPLL and 13 of 42 cases (31.0%) in CSM. In patients with CSM in the KG, C7 the sagittal vertical axis (SVA) was smaller than in the LG. In patients with cervical OPLL in the KG, C2-C7 angle, C2-C7 SVA, and thoracic kyphosis (TK) were smaller than those in the LG. In OPLL, the age of the KG was younger than that of LG; however, this was not a significant difference in CSM.

Conclusion

In patients with cervical OPLL without preoperative global spinal sagittal imbalance, preoperative small C2-C7 angle, C2-C7 SVA, TK, and younger age were typical characteristics of postoperative cervical kyphosis after ELAP.

Analysis of Factors Contributing to Repeat Surgery in Multi-Segments Cervical Ossification of Posterior Longitudinal Ligament

OBJECTIVE

Cervical ossification of the posterior longitudinal ligament (OPLL) can be treated via anterior or posterior approach, or both. The optimal approach depends on the characteristics of OPLL and cervical curvature. Although most patients can be successfully treated by a single surgery with the proper approach, renewed or newly developed neurological deterioration often requires repeat surgery.

METHODS

Twenty-seven patients with renewed or newly developed neurological deterioration requiring salvage surgery for multi-segment cervical OPLL were enrolled. Ten patients (group AP) underwent anterior approach, and 17 patients (group PA) underwent posterior approach at the initial surgery. Clinical and radiological data from initial and repeat surgeries were obtained and analyzed retrospectively.

RESULTS

The intervals between the initial and repeat surgeries were 102.80±60.08 months (group AP) and 61.00±8.16 months (group PA) (p<0.05). In group AP, the main OPLL lesions were removed during the initial surgery. There was a tendency that the site of main OPLL lesions causing renewed or newly developed neurological deterioration were different from that of the initial surgery (8/10, p<0.05). Repeat surgery was performed for progressed OPLL lesions at another segment as the main pathology. In group PA, the main OPLL lesions at the initial surgery continued as the main pathology for repeat surgery. Progression of kyphosis in the cervical curvature (Cobb's angle on C2-7 and segmental angle on the main OPLL lesion) was noted between the initial and repeat surgeries. Group PA showed more kyphotic cervical curvature compared to group AP at the time of repeat surgery (p<0.05).

CONCLUSION

The reasons for repeat surgery depend on the type of initial surgery. The main factors leading to repeat surgery are progression of remnant OPLL at a different segment in group AP and kyphotic change of the cervical curvature in group PA.

Potential risk factors for poor outcome after anterior surgery for patients with cervical ossification of the posterior longitudinal ligament

Objective

Our purpose here was to identify risk factors of poor outcome after anterior operation in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

This study retrospectively reviewed 98 patients who underwent anterior surgery for improving neurological symptoms. The Japanese Orthopedic Association (JOA) recovery rate <50% was defined as poor surgical outcome. We investigated the relationship between various predictors and outcome by logistic regression analysis and receiver operating characteristic curves. To explore the cause of cerebrospinal fluid (CSF) leakage, we used the Mann–Whitney U-test, χ² test, or independent t-test.

Results

Multivariate logistic regression analysis showed that age (odds ratio [OR] =1.1, 95% confidence interval [CI] =1.03–1.18, P=0.005), occupying ratio of OPLL (OR =1.08, 95% CI =1.03–1.12, P=0.001), and residual ratio of OPLL (OR =1.07, 95% CI =1.02–1.13, P=0.008) were independently associated with poor outcome. The cutoffs of the above risk factors were set at 63.5 years, 39.65%, and 25.165%, respectively. Predictors for CSF leakage were occupying ratio of OPLL, the K-line, and shape of the ossified lesion (P<0.001, P=0.019, and P=0.003).

Conclusion

These findings suggest that advanced age, high occupying ratio of OPLL, and high residual ratio of OPLL were risk factors for postoperative poor outcome in patients with OPLL. In addition, the high occupying ratio of OPLL, the K-line (−), and hill-shape ossification were potential causes of CSF leakage.