Long-term results after expansive open-door laminoplasty for the segmental-type of ossification of the posterior longitudinal ligament of the cervical spine: a comparison with nonsegmental-type lesions

Anterior decompression and posterior total laminectomy with fusion for ossification of the cervical posterior longitudinal ligament

Aims

Surgical approaches to cervical ossification of the posterior longitudinal ligament (OPLL) remain controversial. The purpose of the present study was to analyze and compare the long-term neurological recovery following anterior decompression with fusion (ADF) and posterior laminectomy and fusion with bone graft and internal fixation (PLF) based on > ten-year follow-up outcomes in a single centre.

Methods

Included in this retrospective cohort study were 48 patients (12 females; mean age 55.79 years (SD 8.94)) who were diagnosed with cervical OPLL, received treatment in our centre, and were followed up for 10.22 to 15.25 years. Of them, 24 patients (six females; mean age 52.88 years (SD 8.79)) received ADF, and the other 24 patients (five females; mean age 56.25 years (SD 9.44)) received PLF. Clinical data including age, sex, and the OPLL canal-occupying ratio were analyzed and compared. The primary outcome was Japanese Orthopaedic Association (JOA) score, and the secondary outcome was visual analogue scale neck pain.

Results

Compared with the baseline, neurological function improved significantly after surgery in all patients of both groups (p < 0.001). The JOA recovery rate in the ADF group was significantly higher than that in the PLF group (p < 0.001). There was no significant difference in postoperative cervical pain between the two groups (p = 0.387). The operating time was longer and intraoperative blood loss was greater in the PLF group than the ADF group. More complications were observed in the ADF group than in the PLF group, although the difference was not statistically significant.

Conclusion

Long-term neurological function improved significantly after surgery in both groups, with the improvement more pronounced in the ADF group. There was no significant difference in postoperative neck pain between the two groups. The operating time was shorter and intraoperative blood loss was lower in the ADF group; however, the incidence of perioperative complications was higher.

Does the presence of preoperative neck pain impact clinical outcomes after posterior decompression in patients with cervical ossification of the posterior longitudinal ligament?: Retrospective multicenter cohort study

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVES

To evaluate how preoperative neck pain influences clinical outcomes following posterior decompression for cervical ossification of the posterior longitudinal ligament (OPLL).

SETTING

Fourteen medical institutions in Japan.

METHODS

We enrolled 90 patients with cervical OPLL who underwent posterior decompression and were followed for a minimum of two years. We collected demographic data, medical history, and imaging findings. Patients were divided into two groups based on preoperative neck pain presence (Pre-op. neck pain (-) and (+) groups), and their outcomes were compared.

RESULTS

There were no significant differences in patient demographics between the Pre-op. neck pain (-) and (+) groups. Both groups showed similar distributions of ossification types and K-line positivity. Perioperative complications were comparable between the two groups. Radiographic analysis revealed no significant differences in C2-7 angles or cervical range of motion, pre- and postoperatively. Both groups demonstrated significant improvement in postoperative Japanese orthopedic association (JOA) scores, but there were no significant differences in scores or recovery rates. In the Pre-op. neck pain (-) group, factors associated with appearance of postoperative neck pain included pre- and postoperative lower JOA scores and larger C2-7 angles in neutral and extension positions.

CONCLUSIONS

It emerges that lower pre- and postoperative JOA scores or larger C2-7 angles in neutral and extension positions predispose to postoperative neck pain even in those patients without preoperative neck pain. Therefore, this is worth discussing at the time of consenting patients for surgical decompression and fixation.

Impact of C3 laminectomy on cervical sagittal alignment in cervical laminoplasty: a prospective, randomized controlled trial comparing clinical and radiological outcomes between C3 laminectomy with C4-C6 laminoplasty and C3-C6 laminoplasty

BACKGROUND CONTEXT

C3 laminectomy in cervical laminoplasty is a modified laminoplasty technique that can preserve the semispinalis cervicis muscle attached to the C2 spinous process. Several previous studies have shown that this technique can lead to better outcomes of postoperative axial neck pain and C2-C3 range of motion (ROM) than conventional cervical laminoplasty. However, there is still a lack of understanding of total and proportional postoperative cervical sagittal alignment outcomes.

PURPOSE

To assess the effects of C3 laminectomy in cervical laminoplasty on postoperative cervical alignment and clinical outcomes.

DESIGN

A single-center, patient-blinded, randomized controlled trial.

PATIENT SAMPLE

We included consecutive 126 patients diagnosed with cervical spondylotic myelopathy (CSM) or ossification of posterior longitudinal ligament (OPLL) who were scheduled for cervical laminoplasty from March 2017 to January 2020.

OUTCOME MEASURES

The primary outcome measures were C2-C7 Cobb angle (CA) and neck disability index (NDI). Secondary outcomes measures included other clinical outcomes and radiographic parameters including segmental Cobb angle and presence of C2-C3 interlaminar fusion.

METHODS

Patients were randomly allocated to either the C3 laminectomy with C4-C6 laminoplasty group (LN group) or the C3-C6 laminoplasty group (LP group) at a 1:1 ratio. Laminoplasty was performed using a unilateral open-door technique and stabilized with titanium mini plates. A linear mixed model analysis was employed to examine the longitudinal data from postoperative 1-year through 3-year. Additional analysis between three types of cervical sagittal alignment morphology was done.

RESULTS

Among 122 patients who were randomly allocated to one of two groups (LN group, n=61; LP group, n=61), modified intent-to-treat analysis was done for 109 patients (LN group, n=51, LP group, n=58) who had available at least a year of postoperative data. Postoperative C2-C7 CA was not significantly different between the two groups. However, NDI was significantly different between the two groups (12.8±1.0 in the LN group vs 8.6±1.0 in LP group, p=.005), which exceeded the minimum clinically important difference (MCID). The postoperative C2-C3 CA was significantly greater in the LN group (7.1±0.5° in LN group vs 3.2±0.5° in LP group, p<.001) while C4-C7 CA was significantly smaller in the LN group (3.9±0.8° in LN group vs 7.7±0.7° in LP group, p<.001) with greater cSVA in the LN group (31.6±1.4 mm in LN group vs 25.5±1.3 mm in LP group at postoperative 3-year, p=.002). Postoperative Euro-Quality of Life-5 Dimension (EQ-5D), numerical rating scores for neck pain (NRS-N) were significantly better in the LP group than in the LN group (all p<.05) and only EQ-5D surpassed the MCID. The C2-C3 fusion rate was significantly different between the LN group (9.8%) and the LP group (44.8%) (p<.001). The LN group showed a higher prevalence of a specific cervical alignment morphology characterized by a sigmoid shape with proximal lordosis and distal kyphosis (S curve). This S curve demonstrated significantly unfavorable outcomes across multiple outcome variables.

CONCLUSION

The impact of C3 laminectomy in cervical laminoplasty on postoperative kyphosis among patients with CSM or OPLL did not significantly differ from that of C3-C6 laminoplasty. However, C3 laminectomy in cervical laminoplasty might result in an unfavorable clinical outcome with an unbalanced cervical sagittal alignment characterized by a sigmoid shape with proximal lordosis and distal kyphosis.

Comparison of Clinical Outcomes of Cervical Laminoplasty for Cervical Spondylotic Myelopathy: Double-Door With Lamina Staple, Single-Door With Miniplate, and Double-Door With Spacer-A 2-Year Follow-Up Study

BACKGROUND

There were few studies to compare the outcomes of different types of cervical laminoplasties.

OBJECTIVE

To compare the clinical outcomes of double-door cervical laminoplasty with lamina staple (double-door staple), single-door cervical laminoplasty with miniplate (single-door miniplate), and double-door cervical laminoplasty with spacer (double-door spacer).

METHODS

The study involved 166 patients with cervical spondylotic myelopathy (CSM). Fifty-two patients underwent double-door staple, 63 patients underwent single-door miniplate, and 51 patients underwent double-door spacer. The clinical outcomes were measured.

RESULTS

There was no significant difference in Japanese Orthopedic Association score among the 3 groups ( P > .05). The operation time was significantly shorter in double-door staple and single-door miniplate groups than in the double-door spacer group ( P < .005). The estimated blood loss was significantly more in the single-door miniplate group than in double-door staple and double-door spacer groups ( P < .005). The expansion ratio of cervical intraspinal cross-sectional area decreased in the order of double-door staple > double-door spacer > single-door miniplate. There were no significant differences in the expansion ratio of dural sac cross-sectional area among the 3 groups.

CONCLUSION

Double-door staple, double-door spacer, and single-door miniplate can achieve favorable clinical outcomes for CSM. The blood loss of double-door staple is less than that of single-door miniplate, and the operation time of double-door staple is shorter than that of double-door spacer. The mean expansion ratio of cervical intraspinal cross-sectional area decreased in the order of double-door staple > double-door spacer > single-door miniplate. Overall, double-door staple is a safe and innovative alternative choice for treatment of CSM.

Accuracy of the trough position in expansive open-door cervical laminoplasty using computer navigation techniques: a single-centre retrospective study

PURPOSE

This study aims to assess whether computer navigation can improve the accuracy of the trough position and clinical outcomes of expansive open-door cervical laminoplasty (EOLP).

METHODS

We reviewed a single centre of 28 conventional EOLP and 24 computer navigation EOLP cases. The conventional group had 102 laminae while the navigation group had 88. The distance from the medial cortex to the pedicle on the open-door side (OD) and hinge side (HD) was measured. Furthermore, the area of the spinal canal corresponding to each lamina before and after the surgical procedure was also measured. We then compared the differences in radiographic parameters and clinical outcomes between the two groups.

RESULTS

OD and HD were smaller in the navigation group compared to the conventional group, and the enlarged area of the spinal canal was larger in the navigation group than in the conventional group. The Japanese Orthopaedic Association (JOA) scores one year after the surgical procedure improved in both groups compared to the pre-operative period, and the JOA recovery rate was higher in the navigation group. The incidence of hinge fracture was lower in the navigation group, and the incidence of C5 palsy and axial pain was not statistically different between the two groups.

CONCLUSION

The use of computer navigation techniques has the potential to significantly improve the accuracy of EOLP compared to conventional procedures. It has been shown to more fully expand the spinal canal and contribute to clinical efficacy.

Incidence and risk factors of postoperative symptomatic spinal epidural hematoma in cervical spine surgery: a single center, retrospective study of 18,220 patients

PURPOSE

The goal of this research is to explore the incidence and risk factors of symptomatic spinal epidural hematoma (SSEH) following cervical spine surgery.

METHODS

Patients with SSEH from January 2009 to February 2019 were identified as hematoma group. Two control subjects without SSEH were randomly selected for each patient in SSEH group as control group. We collected gender, age, body mass index (BMI), ossification of the posterior ligament (OPLL), comorbidities, anti-platelet or anti-coagulate treatment, coagulation function, segments, instrumental fixation, surgical approach, surgical procedure, duration of surgery and estimated blood loss, which might affect the occurrence of symptomatic epidural hematoma. T-test and Chi-square test were used to univariable test. Multifactor logistic regression analysis was used to investigate the correlation with symptomatic epidural hematoma, furthermore its causes were explored.

RESULTS

Among 18,220 patients, 43 subjects developed SSEH, the incidence was 0.24%. The median time from the end of index surgery to SSEH was 150  min (25 and 75 percentile: 85  min to 290  min). The neurologic function before evacuation by modified Frankel scale is grade B in 5 patients, C in 32 patients, grade D in 6 patients. All patients' symptoms relieved partially or completely after evacuation. All patients with neurologic deficit worse than grade C pre-evacuation had at least one-grade improvement except for one patient. Multifactor logistic regression revealed OPLL involved segments are significantly correlated to the incidence of postoperative symptomatic epidural hematoma (P < 0.05), with a cut-off value of 1.5 levels.

CONCLUSION

OPLL involved segments are significantly correlated to the incidence of postoperative symptomatic epidural hematoma.

Significance of Vertebral Body Sliding Osteotomy as a Surgical Strategy for the Treatment of Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Vertebral body sliding osteotomy (VBSO) has previously been reported as a technique to decompress ossification of the posterior longitudinal ligament (OPLL) by translating the vertebral body anteriorly. This study aimed to evaluate the radiological and clinical efficacies of VBSO and clarify the surgical indications of VBSO for treating myelopathy caused by OPLL.

METHODS

Ninety-seven patients with symptomatic OPLL-induced cervical myelopathy treated with VBSO or laminoplasty who were followed up for more than 2 years were retrospectively reviewed. Cervical alignment, range of motion, fusion, modified K-line (mK-line) status, and minimum interval between ossified mass and mK-line (INT_(min)), and the Japanese Orthopaedic Association (JOA) score were assessed. Patients in the VBSO group were compared with those who underwent laminoplasty.

RESULTS

Cervical lordosis and INT_(min) significantly increased in the VBSO group. All patients in the VBSO group assessed as mK-line (-) preoperatively were assessed as mK-line (+) postoperatively. However, in the LMP group, the mK-line status changed from (+) preoperatively to (-) postoperatively in 3 patients. Final JOA score (p = 0.02) and JOA score improvement (p = 0.01) were significantly higher in the VBSO group. JOA recovery ratio (p = 0.03) and proportion of patients with a recovery rate ≥50% were significantly higher in the VBSO group (p < 0.01).

CONCLUSIONS

VBSO is an effective surgical option for OPLL-induced myelopathy, demonstrating favorable neurological recovery and lordosis restoration with low complication rates. It is best indicated for kyphotic alignment, OPLL with a high space-occupying ratio, and OPLL involving ≤3 segments.

Severity of Myelopathy is Closely Associated With Advanced Age and Signal Intensity Change in Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Nationwide Investigation

STUDY DESIGN

Prospective, nationwide case series.

OBJECTIVE

To identify preoperative factors associated with myelopathy and neurological impairment in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

Various studies have reported clinical outcomes following the surgical treatment of OPLL. However, there has been no large-scale study of preoperative clinical features in patients with cervical OPLL.

MATERIALS AND METHODS

Data were prospectively collected from 28 institutions nationwide in Japan. In total, 512 patients with neurological impairment caused by cervical OPLL requiring surgery were enrolled. Basic demographic and clinical data, including age, sex, diabetes status, body mass index, smoking history, and disease duration were collected. C2-7 lordotic angle, canal narrowing ratio, range of motion in flexion-extension at C2-7, and type of OPLL were evaluated on lateral radiographs to identify factors influencing the clinical features of patients with OPLL in whom surgery was planned.

RESULTS

Complete documentation was available for 490 patients (362 male, 128 female). In total, 34 patients had the localized type, 181 had the segmental type, 64 had the continuous type, and 211 had the mixed type. Although there were no significant differences in age, body mass index, disease duration, Japanese Orthopedic Association (JOA) score, and lordotic angle at C2-7 according to the type of OPLL, significant differences were observed in a range of motion at C2-7 and the canal narrowing ratio among the 4 types. Multiple regression analysis revealed that the JOA score was significantly associated with age and signal intensity change on magnetic resonance imaging.

CONCLUSIONS

This is the first large-scale, prospective, multicenter case series study to investigate factors influencing preoperative neurological status in patients with OPLL. Age and signal intensity change on magnetic resonance images were significantly associated with JOA score in patients requiring surgery.

LEVEL OF EVIDENCE

Level II.

Comparison of laminoplasty and posterior fusion surgery for cervical ossification of posterior longitudinal ligament

This prospective multicenter study, established by the Japanese Ministry of Health, Labour and Welfare and involving 27 institutions, aimed to compare postoperative outcomes between laminoplasty (LM) and posterior fusion (PF) for cervical ossification of the posterior longitudinal ligament (OPLL), in order to address the controversy surrounding the role of instrumented fusion in cases of posterior surgical decompression for OPLL. 478 patients were considered for participation in the study; from among them, 189 (137 and 52 patients with LM and PF, respectively) were included and evaluated using the Japanese Orthopaedic Association (JOA) scores, the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and radiographical measurements. Basic demographic and radiographical data were reviewed, and the propensity to choose a surgical procedure was calculated. Preoperatively, there were no significant differences among the participants in terms of patient backgrounds, radiographical measurements (K-line or cervical alignment on X-ray, OPLL occupation ratio on computed tomography, increased signal intensity change on magnetic resonance imaging), or clinical status (JOA score and JOACMEQ) after adjustments. The overall risk of perioperative complications was found to be lower with LM (odds ratio [OR] 0.40, p = 0.006), and the rate of C5 palsy occurrence was significantly lower with LM (OR 0.11, p = 0.0002) than with PF. The range of motion (20.91° ± 1.05° and 9.38° ± 1.24°, p < 0.0001) in patients who had PF was significantly smaller than in those who had LM. However, multivariable logistic regression analysis showed no significant difference among the participants in JOA score, JOA recovery rate, or JOACMEQ improvement at two years. In contrast, OPLL progression was greater in the LM group than in the PF group (OR 2.73, p = 0.0002). Both LM and PF for cervical myelopathy due to OPLL had resulted in comparable postoperative outcomes at 2 years after surgery.

Laminectomy with instrumented fusion vs. laminoplasty in the surgical treatment of cervical ossification of the posterior longitudinal ligament: A multicenter retrospective study

Laminectomy with instrumented fusion (LF) has demonstrated better prevention of ossification of posterior longitudinal ligament (OPLL) growth compared to laminoplasty (LP). There remains uncertainty, however, as to which surgical approach is more beneficial with respect to clinical outcomes and complications. We retrospectively reviewed 273 cervical OPLL patients of more than 3 levels, from the two institutions' databases, who underwent LF or LP between January 1998 and January 2016. Each 273 patient (85 with LF, 188 with LP) was assessed for postoperative neurologic and radiologic outcomes, complications and reoperations. The mean length of follow-up was 40.11 months. There were baseline differences between cohorts. Overall, postoperative JOA recovery rate at last follow up was significantly better in the LP group with similar improvement in visual analog neck score. Postoperative C2-7 Cobb angle was decreased compared to baseline for both LF and LP cohorts, but there was no significant difference between groups. Complications occurred in 19 (22.35%) LF patients, and 11 (5.85%) LP patients, with higher incidence of C5 palsy and instrumentation failure in the LF group. Four LF patients (4.71%) and five LP patients (2.66%) underwent reoperation during the follow up period.

Prognostic factors for neurological outcome after anterior decompression and fusion for proximal-type cervical spondylotic amyotrophy - A retrospective analysis of 77 cases

BACKGROUND

Decompression through an anterior approach is theoretically effective for the surgical treatment of cervical spondylotic amyotrophy (CSA), because the pathology usually locates at the anterior side. However, most previous studies investigated posterior surgery or a mix of anterior surgery and posterior surgery in their investigation. Only a few small case series have investigated the surgical outcomes of anterior decompression and fusion (ADF). Therefore, we conducted a multicenter retrospective study that included patients who underwent ADF for proximal-type CSA.

METHODS

We analyzed the outcomes of 77 consecutive spinal surgeries performed on proximal-type CSA patients who underwent ADF. Preoperative and postoperative manual muscle tests (MMT) and the patients' backgrounds, radiological findings, and complications were reviewed. We divided the cases into two groups, good-outcome group (MMT improvement ≧ 2 or improved to MMT 5) and poor-outcome group (others) and evaluated the prognostic factors for outcomes.

RESULTS

Of the 77 patients, 48 (62%) showed good neurological outcome. Multiple compressive lesions at anterior horn (AH) and/or ventral nerve roots (VNRs) were detected in 66 patients (85.7%) on the magnetic resonance images. The patients with a single compressive lesion at VNR or AH tended to show good neurological recovery when compare to those with multiple lesions. Age and duration of symptoms were related to the poor outcome in univariate analysis. Duration of symptoms was an independent factor associated with postoperative neurological outcome. The cut-off value for poor outcome was 7.0 months for the symptom duration (sensitivity: 79%, specificity: 54%, area under the curve: 0.69).

CONCLUSIONS

Patients with proximal-CSA were more likely to have multiple compressive lesions at an AH and/or a VNR. The prognostic factor for poor neurological outcome was duration of symptoms of ≥7 months.

Consensus statement on diagnosis and treatment of cervical ossification of posterior longitudinal ligament from Asia Pacific Spine Society (APSS) 2020

PURPOSE

The study aimed to develop an evidence-based expert consensus statement on diagnosis and treatment of cervical ossification posterior longitudinal ligament (OPLL).

METHOD

Delphi method was used to perform such survey, and the panel members from Asia Pacific Spine Society (APSS) 2020 were invited to answer the open-ended questions in rounds 1 and 2. Then the results were summarized and developed into a Likert-style questionnaire for voting in round 3, and the level of agreement was defined as 80%. In the whole process, we conducted a systematic literature search on evidence for each statement.

RESULTS

Cervical OPLL can cause various degrees of neurological symptoms, an it's thought to be more common in Asia population. CT reconstruction is an important imaging examination to assist diagnosis and guide surgical choice. Segmental, continuous, mixed, and focal type is the most widely used classification system. The non-surgical treatment is recommended for patients with no or mild clinical symptoms, or irreversible neurological damage, or failed surgical decompression, or condition cannot tolerant surgery, or refusing surgery. As OPLL may continue to develop gradually, surgical treatment would be considered in their course inevitably. The surgical choice should depend on various conditions, such as involved levels, thickness, and type of OPLL, skill-experiences of surgeons, which are listed and discussed in the article.

CONCLUSION

In this statement, we describe the clinical features, classifications, and diagnostic criteria of cervical OPLL, and review various surgical methods (such as their indications, complications), and provide a guideline on their choice strategy.

Expansion of Spinal Canal with Lift-Open Laminoplasty: A New Method for Compression Cervical Myelopathy

OBJECTIVE

This study is to introduce lift-open laminoplasty and verify the increase of the spinal canal area following this surgical technique according to the preoperative anatomical measurement.

METHODS

There are 82 patients (43 male and 39 female) analyzed in our study from January 2019 to December 2020. The average age was 63.2 ± 3.21 years (from 41 to 84 years). All of them were treated with open-door laminoplasty, with a decompression segment range from C3 to C6. The increase of the spinal canal area after open-door laminoplasty was measured on postoperative CT images of the patients, and the distances between both lamina-facet junctions and lamina length was measured on preoperative CT images. Using the Pythagorean theorem for the equation of calculation area after the expansile open-door laminoplasty. Based on previous measurement parameters, spinous process length, lateral mass width, distance between osteotomy line and lamina-facet junctions line were additionally measured on preoperative CT images. Pythagorean theorem was used for calculating the area after the expansile lift-open laminoplasty. The results were recorded and a statistical analysis was undertaken. Then, there were six patients (five male and one female) treated with lift-open laminoplasty on C6, open-door on C3-C5, who suffer from cervical spondylotic myelopathy from December 2020 to January 2021. The average age was 60.3 ± 1.7 years (from 56 to 71 years). Operation time, blood loss, and Japanese Orthopaedic Association (JOA) score recovery rate were recorded. Intraoperative and postoperative complications were observed.

RESULTS

The increase of the spinal canal area after open-door laminoplasty measured on postoperative CT images was 123.01 ± 17.06 mm² and the calculation of the increase of the spinal canal areausing the Pythagorean theorem after open-door laminoplasty was 122.86 ± 15.86 mm² . A comparison of the actual value with calculative value showed no significant difference (T value = 0.057, P value = 0.955). The calculation of the increase of the spinal canal area after lift-open laminoplasty was 183.57 ± 62.99 mm² , which was larger than that after open-door laminoplasty (T value = 8.462, P value < 0.001). Mean operation time was 153.3 min and operative blood loss was 600 mL of the six patients treated with lift-open laminoplasty. At 1 month follow-up, all patients had recovered well. JOA score recovery rate was 37.6% and no intraoperative and postoperative complications occurred.

CONCLUSION

Lift-open laminoplasty could preserve nearly 100% of extensor muscle, avoid damaging C7 paraspinal muscles and C6-7 posterior muscle-ligament complex, reconstruct the spinous process firmly in the midline, and expand adequate spinal canal area after operation. These advantages could reduce the incidence rate of complications and bring better clinical results than traditional laminoplasty.

"Only Spinal Fixation" as Surgical Treatment of Cervical Myelopathy Related to Ossified Posterior Longitudinal Ligament: Review of 52 Cases

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) is a hyperostotic condition resulting in a progressive narrowing of the spinal canal and subsequent neurologic deficits. Although systemic and local factors in combination with genetic abnormality have been considered in its etiopathogenesis, OPLL remains a poorly understood pathology. Surgical management of OPLL and the choice of the most appropriate treatment are still controversial issues. Here the authors report a series of OPLL-affected patients treated by "only-fixation" technique.

METHODS

Between June 2012 and June 2019, 52 patients having OPLL were treated by a surgical strategy involving only spinal fixation without any form of bone or soft tissue decompression. Facetal fixation for both the atlantoaxial and subaxial spine formed the basis of the surgical treatment. Clinical parameters, analysis of video recordings before and after surgery, and patient self-assessment were included in the analysis of outcome.

RESULTS

During the mean follow-up period there was an immediate postoperative and progressive recovery in symptoms in 51 patients. Of 14 patients who were wheelchair bound before surgery, 12 walked independently on follow-up assessment of 6 months. All patients had successful arthrodesis in the surgically treated segments. There were no infective- or implant-related complications.

CONCLUSIONS

Decision making in the surgical management of cervical OPLL is still controversial. The concept of spinal instability has been shown to be a nodal point in the pathogenesis of OPLL, and "only-spinal fixation" can be considered a rationale for an appropriate surgical treatment.

The Severity of Cervical Disc Degeneration Does Not Impact 2-year Postoperative Outcomes in Patients With Cervical Spondylotic Myelopathy Who Underwent Laminoplasty

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to evaluate the impact of cervical disc degeneration (CDD) severity on 2-year postoperative outcomes following laminoplasty.

SUMMARY OF BACKGROUND DATA

The impact of CDD on postoperative outcomes of cervical laminoplasty has not been well established.

METHODS

A total of 144 patients who underwent open-door laminoplasty for cervical spondylotic myelopathy (CSM) were enrolled. Six cervical discs were independently analyzed for degeneration severity using a previously reported grading system (grade 0: none, grade 3: severest). The relationship between the segmental range of motion (ROM) and the severity of CDD was evaluated. Subsequently, after dividing overall patients into mild and severe CDD groups by the average of CDD scores, the mixed-effect model was applied to assess 2-year postoperative outcomes, including physician-assessed myelopathy scores, patient-reported outcomes, and preoperative radiographic parameters. Finally, as additional analysis, the severe CDD group was further divided into two groups: group 1 included patients with a grade 3 CDD change in their most stenotic level and group 2 included the others. The 2-year postoperative myelopathy score was compared between groups 1 and 2.

RESULTS

The cervical segments with grade 3 CDD showed significantly smaller ROM compared with those with grade 0, 1, or 2 CDD (P < 0.01). There were no significant differences in postoperative improvements in myelopathy, pain, patient-reported physical and mental status, and radiographic parameters, except for quality of life (QOL) scores between CDD groups. A significant (P = 0.02) postoperative improvement in QOL scores was noted in the severe CDD group. In an additional analysis, myelopathy score at 2 years postoperatively was significantly higher in group 1 than group 2 (P = 0.041).

CONCLUSION

The severity of CDD did not negatively impact 2-year postoperative laminoplasty outcomes. The postulated reason is that the decreased segmental instability in the level with severe CDD may affect surgical outcomes positively.

LEVEL OF EVIDENCE

3.

Ten-Year Surgical Outcomes and Prognostic Factors for French-Door Laminoplasty in the Treatment of Multilevel Cervical Spondylotic Myelopathy

Objective

To analyze the ten-year surgical outcomes and postoperative complications of French-Door laminoplasty (FDL) in the management of multilevel cervical spondylotic myelopathy (MCSM) and analyze the prognostic factors for FDL in treating MCSM.

Methods

64 patients with MCSM, who were operated by FDL, were included in this study and followed up for at least 10 years. Clinical assessments including modified Japanese Orthopaedic Association (mJOA) score, age at surgery, preoperative symptom duration, operative time, blood loss and postoperative complications, radiological assessments including Cobb angle, cervical range of motion (ROM), intramedullary signal intensity on T2W MRI, canal narrowing ratio (CNR), and maximum spinal cord compression (MSCC). mJOA score, Cobb angle, cervical ROM, intramedullary signal intensity on T2W MRI, and CNR were assessed before surgery and at the final follow-up.

Results

The average mJOA score was significantly improved from preoperative 10.32 ± 1.63 points to 15.10 ± 0.62 points at the final follow-up (p < 0.05). The average RR of the mJOA score at the final follow-up was 69.10 ± 7.32%. The cervical Cobb angle and ROM decreased significantly at the final follow-up. Patients with high intramedullary signal intensity of T2W MRI or CNR more than 50% showed a lower RR of the mJOA score. Correlation analysis revealed that preoperative symptom duration and intramedullary signal intensity of T2W MRI, CNR, MSCC, and blood loss were significantly correlated with the RR of the mJOA score. Gender, operative method, and age at surgery were significantly correlated with the preservation rate of ROM. Operative time was significantly correlated with the incidence of axial symptoms.

Conclusions

The ten-year clinical outcomes of FDL were satisfactory. Higher intramedullary signal intensity of T2W MRI and a greater CNR predicted poorer prognoses.

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.

How Does Ossification of Posterior Longitudinal Ligament Progress in Conservatively Managed Patients?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to elucidate the progression of ossification of the posterior longitudinal ligament (OPLL) in conservatively managed patients and determine its risk factors SUMMARY OF BACKGROUND DATA.: Although several studies have demonstrated how OPLL progresses after laminoplasty or fusion, its progression in conservatively managed patients remains unclear.

METHODS

The vertical length of the ossified mass and its thickness at each segment were evaluated on sagittal computed tomography images. Patients with vertical growth >2 mm were included in the vertical progression group. Segments with a thickness progression >1 mm were classified as thickness progressed segments, and patients who had at least one progressed segment were included in the thickness progression group. Based on the characteristics at each disc level, the ossified mass at each segment was classified into four types: type 1, no disc space involvement; type 2, involving the disc space, but not crossing; type 3, crossing the disc space, but not fused; and type 4, completely fused.

RESULTS

The progression of ossified mass was observed in younger patients (P < 0.01) and in C2-C3 involvement (P < 0.01) cases. Moreover, progression in both directions was observed more frequently in the mixed-type OPLL (P < 0.01). Progression occurred most often in type 3 segments (72.0%, P < 0.01). In type 3 segments, thickness progression was found more frequently in segments with segmental range of motion (ROM) ≥5° (55.6% vs. 27.8%, P = 0.04). The proportion of segments whose initial thickness was >5 mm was significantly higher among progressed segments (60.0% vs. 35.2%, P = 0.03).

CONCLUSION

Young age, C2-C3 involvement, and mixed-type OPLL are risk factors for OPLL progression. Segments with morphology of crossing the segment, but without fusion (type 3), segmental ROM ≥5°, and initial thickness >5 mm need special attention.

LEVEL OF EVIDENCE

3.

A Systematic Review of Definitions for Neurological Complications and Disease Progression in Patients Treated Surgically for Degenerative Cervical Myelopathy

STUDY DESIGN

Systematic review.

OBJECTIVE

This review aims to (1) outline how neurological complications and disease progression are defined in the literature and (2) evaluate the quality of definitions using a novel four-point rating system.

SUMMARY OF BACKGROUND DATA

Degenerative cervical myelopathy (DCM) is a progressive, degenerative spine disease that is often treated surgically. Although uncommon, surgical decompression can be associated with neurological complications, such as C5 nerve root palsy, perioperative worsening of myelopathy, and longer-term deterioration. Unfortunately, important questions surrounding these complications cannot be fully addressed due to the heterogeneity in definitions used across studies. Given this variability, there is a pressing need to develop guidelines for the reporting of surgical complications in order to accurately evaluate the safety of surgical procedures.

METHODS

An electronic database search was conducted in MEDLINE, MEDLINE in Process, EMBASE and Cochrane Central Register of Controlled Trials for studies that reported on complications related to DCM surgery and included at least 10 surgically treated patients. Data extracted included study design, surgical details, as well as definitions and rates of surgical complications. A four-point rating scale was developed to assess definition quality for each complication.

RESULTS

Our search yielded 2673 unique citations, 42 of which met eligibility criteria and were summarized in this review. Defined complications included neurological deterioration, late onset deterioration, perioperative worsening of myelopathy, C5 palsy, nerve root or upper limb palsy or radiculopathy, surgery failure, inadequate decompression and progression of ossified lesions. Reported rates of these complications varied substantially, especially those for neurological deterioration (0.2%-33.3%) and progression of ossified lesions (0.0%-86.7%).

CONCLUSION

Reported incidences of various complications vary widely in DCM surgery, especially for neurological deterioration and progression of ossified lesions. This summary serves as a first step for standardizing definitions and developing guidelines for accurately reporting surgical complications.

LEVEL OF EVIDENCE

2.

Cervical Spinal Cord Injury Associated With Neck Flexion in Posterior Cervical Decompression

STUDY DESIGN

A retrospective analysis of prospectively collected data of 179 consecutive patients who underwent intraoperative neurophysiological monitoring during posterior cervical spine surgery for compression myelopathy.

OBJECTIVE

To evaluate preoperative factors in patients with deteriorating spinal cord function due to flexion of the neck during posterior cervical spine surgery by observing changes in waveforms on intraoperative monitoring.

SUMMARY OF BACKGROUND DATA

We encountered several cases of intraoperative monitoring warning alerts because of neck flexion during posterior cervical spine surgery. We investigated the incidence rate and intraoperative predictors of deteriorating spinal cord function caused by neck flexion based on waveform changes.

MATERIALS AND METHODS

Subjects were 179 patients who underwent posterior cervical decompression for spinal cord compression. When warning alarms were set off by amplitude changes in the period between skin incision and exposure of the lamina, the neck position was changed from flexion to neutral, and patients whose electrical potentials recovered following cervical repositioning were placed in the flexion-induced potential reduction group. We then analyzed and extracted risk factors for flexion-induced reduction in electrical potentials.

RESULTS

In total, 156 patients were analyzed in this study. Monitoring alarms went off intraoperatively for 7 patients (4.5%) at the time of posterior cervical spine exposure. With regard to the most compressed level, the occupancy ratio of the anterior compression component, the kyphotic angle in flexion, and range of motion in the neutral position to flexion were significantly associated with flexion-induced reduction in electrical potentials. Furthermore, logistic regression analysis extracted the occupancy ratio of the anterior compression component at the most compressed level and the kyphotic angle of the most compressed level in flexion.

CONCLUSIONS

Our findings suggest that a large anterior compression component and large kyphotic angle in neck flexion at the most compressed level are risk factors for intraoperative spinal cord injury during posterior cervical spine surgery.

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.

Combined Laminoplasty and Posterior Fusion for Cervical Spondylotic Myelopathy Treatment: A Literature Review

Study Design

A literature review.

Purpose

To explore the utility of laminoplasty in combination with instrumented fusion, with a focus on neurological outcomes and changes in kyphotic deformity.

Overview of Literature

Management of cervical spondylotic myelopathy (CSM) to reduce morbidity within the neurosurgical population.

Methods

A US National Library of Medicine PubMed search was conducted for manuscripts pertaining to cervical laminoplasty and fusion for the management of CSM. Several relevant studies were shortlisted for review, and the bibliographies of the articles were searched for additional references. The search was limited to human studies, English-language literature, and reports on more than one patient.

Results

Combined laminoplasty and fusion was found to provide at least comparable, if not superior, neurological outcomes in specific patient populations with CSM. The Japanese Orthopedic Association scores, local kyphosis, and C2–C7 angle have been reviewed in several manuscripts, and improvement in each of these categories was found with laminoplasty and fusion.

Conclusions

The treatment of CSM necessitates an individualized approach based on the pathoanatomical variation. Laminoplasty and fusion can be appropriately used for patients with CSM in a setting of local kyphotic deformity, ossification of the posterior longitudinal ligament, associated segmental instability, and the need for strong stabilization.

Increased stress and strain on the spinal cord due to ossification of the posterior longitudinal ligament in the cervical spine under flexion after laminectomy

Myelopathy in the cervical spine due to cervical ossification of the posterior longitudinal ligament could be induced by static compression and/or dynamic factors. It has been suggested that dynamic factors need to be considered when planning and performing the decompression surgery on patients with the ossification of the posterior longitudinal ligament. A finite element model of the C2-C7 cervical spine in the neutral position was developed and used to generate flexion and extension of the cervical spine. The segmental ossification of the posterior longitudinal ligament on the C5 was assumed, and laminectomy was performed on C4-C6 according to a conventional surgical technique. For various occupying ratios of the ossified ligament between 20% and 60%, von-Mises stresses, maximum principal strains in the spinal cord, and cross-sectional area of the cord were investigated in the pre-operative and laminectomy models under flexion, neutral position, and extension. The results were consistent with previous experimental and computational studies in terms of stress, strain, and cross-sectional area. Flexion leads to higher stresses and strains in the cord than the neutral position and extension, even after decompression surgery. These higher stresses and strains might be generated by residual compression occurring at the segment with the ossification of the posterior longitudinal ligament. This study provides fundamental information under different neck positions regarding biomechanical characteristics of the spinal cord in cervical ossification of the posterior longitudinal ligament.

Correlation between preoperative physical signs and functional outcomes after laminoplasty for ossification of the posterior longitudinal ligament

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) can cause myelopathy that is often managed surgically. Knowledge of predictors of surgical outcomes can provide decision support to surgeons. The aims of this study were to investigate the relationships between preoperative physical signs and postoperative functional outcomes in patients with OPLL and to clarify whether physical signs could predict functional outcomes.

METHODS

Fifty-five patients with OPLL who had undergone cervical laminoplasty were included in this study. Six physical signs including hyperreflexia, Babinski sign, sensory disturbance, grip strength, 10-s grip and release test, and bladder dysfunction, and four other factors including age, duration of symptoms, history of minor trauma and preoperative Japanese Orthopaedic Association (JOA) score were investigated as potential predictive prognostic factors using both univariate and multivariate analyses.

RESULTS

The mean recovery rate of JOA score was 62.5 ± 32.5%. The neurological recovery rate was negatively associated with age (P = 0.002), the duration of symptoms (P = 0.002) and Babinski sign (P = 0.007), whereas it was positively correlated with grip strength (P = 0.011). Multiple logistic regression analyses revealed that age (Odds ratio: 0.89, 95% CI: 0.81-0.99) and Babinski sign (Odds ratio: 0.18, 95% CI: 0.04-0.89) were factors associated with functional outcomes.

CONCLUSIONS

Satisfactory functional outcomes could be expected for patients who are young and do not exhibit the Babinski sign, showing that the Babinski sign could be useful as an indicator of the window of opportunity for achieving satisfactory functional outcomes.

Intraoperative evaluation using mobile computed tomography in anterior cervical decompression with floating method for massive ossification of the posterior longitudinal ligament

Background

An anterior decompression and fusion (ADF) with the floating method is an effective procedure for treating ossification of the posterior longitudinal ligament (OPLL), allowing a direct decompressive effect on the spinal cord. However, the procedure is skill-intensive, particularly in cases of OPLL with a high canal-occupying ratio. In such cases, there are potential risks for insufficient decompression due to the incomplete floating of the OPLL. Here, we introduce an anterior decompression procedure for massive OPLL, using an intraoperative computed tomography (CT) with a mobile scanner gantry for the intraoperative evaluation of the decompression. We further evaluated the outcomes of ADF using mobile CT in comparison with a historical control of ADF without intraoperative CT evaluation.

Methods

Fifty OPLL patients who underwent ADF with the floating method were evaluated in this study: 25 patients with intraoperative CT (CT group) and 25 patients without CT (non-CT group). In the CT group, intraoperative CT scanning was performed before freeing the ossification from the surrounding bone tissues. The reconstructed images were reviewed to evaluate the extent of bone decompression and thinning of the OPLL. After review of the images, further thinning of the OPLL or removal of surrounding bone was performed as deemed necessary, to complete the floating of the OPLL.

Results

Patients’ background was similar between the CT and non-CT group. Operating time tended to be shorter for the CT group. On the postoperative CT, incomplete OPLL floating due to “impingement” between the OPLL and the medial aspect of the pedicle or uncovertebral joint was observed for four patients (16.0%) in the non-CT group, whereas insufficient decompression was not observed in the CT group.

Conclusions

Intraoperative CT imaging was effective to avoid insufficient decompression following ADF with the floating method for massive OPLL. We also consider that the intraoperative three-dimensional imaging is helpful for providing informative feedback to surgeons to improve performance in skill-intensive surgeries such as ADF with the floating method.

540° Cervical Realignment Procedure for Extensive Cervical OPLL With Kyphotic Deformity

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to present a novel, two-stage [posterior and anterior-posterior (P-AP) 540°] procedure for extensive cervical ossification of the longitudinal ligament (OPLL) with kyphotic deformity.

SUMMARY OF BACKGROUND DATA

The optimal surgical strategy for extensive cervical OPLL remains a controversial issue. Neurological injury and dural defect are complications of anterior surgery, while a posterior surgery can lead to poor clinical outcomes related to incomplete decompression.

METHODS

We analyzed consecutive cases of patients who underwent procedure described herein, which consists of two stages: the first (P: laminectomy and facet release with segmental screw fixations without rod assembly) and the second 1 week later (AP: multilevel anterior cervical discectomy with fusions (ACDFs) at the apex of the deformity without decompression, placement of lordotic grafts, and posterior fusion). To assess the radiographic parameters, extent of OPLL, maximal canal occupying ratio (%), the distances from the maximal compression to the K-line, and C2-7 angle were analyzed. Clinically, we analyzed visual analog scale of neck and arm pain, neck disability index (NDI), Japanese Orthopedic Association (JOA) score, and complications.

RESULTS

A total of 18 patients were enrolled (M:F = 15:3, mean age 64.5 yrs, mean follow-up was 30 months). The mean extent of the OPLL was 3.8 vertebral body levels. Posterior fusion was performed on a mean 4.5 segments and anterior fusion was on a mean 2.4 segments. The mean C2-7 Cobb angle was improved from 10.5° to -12.2° at follow-up. The K-line distance to the maximal compression and canal occupying ratio were improved from -3.3 mm, 73.5% to 3.8 mm, 38.4%, respectively. Preoperative NDI and JOA scores were significantly improved (18.5 to 9.4 and 8.2 to 14.8) at the last follow-up.

CONCLUSION

The 540° P-AP procedure could provide safe decompression, cervical realignment, and favorable outcomes without the disadvantages of the conventional anterior and/or posterior surgery for extensive cervical OPLL with kyphotic deformity.

LEVEL OF EVIDENCE

4.

Can C3 Laminectomy Reduce Interlaminar Bony Fusion and Preserve the Range of Motion After Cervical Laminoplasty?

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To investigate whether the resection of C3 lamina during cervical laminoplasty can prevent C2-C4 interlaminar bony fusion and preserve the range of motion (ROM) postoperatively.

SUMMARY OF BACKGROUND DATA

Interlaminar bony fusion is a common complication after cervical laminoplasty, especially in the C2-C4. Laminectomy, rather than laminoplasty, of C3 has been recently introduced. Its advantages include minimizing muscle detachment at C2 and reducing postoperative neck pain.

METHODS

A total of 59 patients with cervical spondylotic myelopathy that involved three or more levels, including C3, were consecutively treated with laminoplasty and followed up for more than 3 years after surgery. The first 45 patients underwent open-door laminoplasty at C3 (Lp group) and the subsequent 14 patients underwent laminectomy at C3 rather than laminoplasty (Ln group). The Lp group was further divided into two subgroups based on the development of interlaminar bony fusion at C2-C3 and/or C3-C4: Lp-NF (nonfusion) and Lp-F (fusion) groups. Clinical outcomes and radiographic parameters were assessed pre- and postoperatively.

RESULTS

Nineteen out of 45 patients who underwent laminoplasty demonstrated fusion at 3-year follow up. Fusion developed more commonly in those patients who had a smaller preoperative ROM at C2-C4 segments (Lp-F 14.3° ± 6.9° vs. Lp-NF 21.4° ± 5.3°, P = 0.013). The neck disability index (range, 13.4 ± 7.3 to 6.3 ± 5.2, P < 0.001), visual analog scale for neck pain (range, 2.5 ± 1.7 to 0.9 ± 1.3, P = 0.027), Japanese Orthopedic Association (JOA) score (range, 14.3 ± 1.9 to 16.0 ± 2.4, P < 0.001), and JOA recovery rate (63.4 ± 19.8%) in the Ln group improved postoperatively; however, there was no significant difference in the improvement of these clinical outcomes among all three groups. Postoperative cervical ROM was significantly reduced in all groups; however, the extent of reduction was significantly smaller in the Ln group (10.5°; range, 44.2° ± 9.1° to 33.7 ± 6.0°) than in the Lp-NF (15.1°; range, 45.4° ± 8.5° to 30.3° ± 7.4°) or Lp-F (18.2°; range, 39.6° ± 9.3° to 21.4° ± 10.3°) groups (P < 0.05).

CONCLUSION

C3 laminectomy with laminoplasty can prevent interlaminar bony fusion at C2-C4 and, ultimately, result in better preservation of cervical ROM than C3 laminoplasty. Furthermore, it yields similar clinical outcomes when compared with C3 laminoplasty.

LEVEL OF EVIDENCE

3.

A Comparison of Implants Used in Double Door Laminoplasty : Allogeneic Bone Spacer versus Hydroxyapatite Spacer

Objective

The aim of this study was to compare the clinical and radiological outcomes associated with the use of hydroxyapatite (HA) spacer and allogeneic bone (AB) spacer in laminoplasty.

Methods

From January 2006 to July 2014, 79 patients with cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament underwent cervical laminoplasty. The radiologic parameters were obtained from plain radiography and three-dimensional computed tomography. All images were taken before and after surgery. Cervical lordosis, spinal canal dimension, fusion between lamina and spacer, and resorption of spacer were checked. Clinical outcomes were assessed using visual analog scale and Japanese Orthopedic Association.

Results

Double-door laminoplasty was performed on 280 levels : 182 in the HA group and 98 in the AB group. The mean follow-up was 23.1 months (range : 4–69 months). Similar fusion rates were found in these groups (p=0.3). The resorption rate between lamina and spacer was lower in the HA group (p<0.001). During the immediate postoperative period, the canal dimension of both groups increased compared with the results in the preoperative period. However, the canal dimension of the AB group decreased over time compared with that of the HA group (p<0.001).

Conclusion

Double-door laminoplasty improved the clinical outcomes of both groups. However, the spinal canal dimension in the AB group showed a greater degree of reduction than in the HA group at the final postoperative follow-up. Therefore, we suggest that surgeons consider the use of larger-sized AB spacers in double-door laminoplasties.

Anterior decompression with fusion versus posterior decompression with fusion for massive cervical ossification of the posterior longitudinal ligament with a ≥50% canal occupying ratio: a multicenter retrospective study

BACKGROUND CONTEXT

Previous studies have shown that compared with laminoplasty, anterior decompression with fusion (ADF) is superior for postoperative neurologic improvement in patients with massive cervical ossification of the posterior longitudinal ligament (OPLL) with a ≥50% canal occupying ratio. However, it is unknown which method, ADF or posterior decompression with fusion (PDF), is more effective for the treatment of massive OPLL.

PURPOSE

This study aimed to investigate the surgical outcomes of ADF and PDF for the treatment of massive OPLL.

STUDY DESIGN

A multicenter retrospective case-control study was carried out.

PATIENT SAMPLE

A total of 61 OPLL patients with a ≥50% canal occupying ratio were included in this study. The mean age of the patients was 60.9 years (49 males and 12 females); 39 patients (31 males and 8 females, average age 61.1 years) underwent ADF, and 22 patients underwent PDF (18 males and 4 females, average age 60.6 years).

OUTCOME MEASURES

The data collected from both groups included age, gender, neurologic symptoms evaluated based on the Japanese Orthopedic Association score, neck pain assessed using the visual analogue scale, and radiographic parameters, including cervical lordosis and the OPLL canal occupying ratio.

METHODS

Clinical and radiological outcomes were compared between the ADF and PDF groups with a minimum of 2 years follow-up.

RESULTS

There were no significant differences in the postoperative neurologic recovery rate between the two groups. However, in patients with kyphotic alignment (C2-C7 angle <0 degrees), the recovery rate was higher in the ADF group. Postoperative cervical pain was greater in the PDF group. The improvement in cervical alignment at C2-C7 was greater in the ADF group. The operating time was longer in the ADF group, whereas the intraoperative blood loss was greater in the PDF group. Approach-related complications were more frequently observed in the ADF group than in the PDF group.

CONCLUSIONS

The present study demonstrated that the postoperative recovery rate was similar in the ADF and PDF group. In patients with massive OPLL with kyphotic alignment, neurologic recovery rate in the ADF was superior to that in the PDF (in situ fusion). Additionally, postoperative neck pain was less severe in the ADF group. However, the occurrence of perioperative complications was more common in the ADF group.

More Than 20 Years Follow-up After En Bloc Cervical Laminoplasty

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of the study was to evaluate clinical outcomes and to clarify the potential risks of cervical laminoplasty by a long-term follow-up of more than 20 years.

SUMMARY OF BACKGROUND DATA

There is no follow-up report exceeding 20 years after cervical laminoplasty.

METHODS

Two hundred sixteen patients underwent en bloc cervical laminoplasty for the treatment of cervical compressive myelopathy due to cervical spondylosis or ossification of the posterior longitudinal ligament between 1981 and 1994. Of these, 148 patients with a follow-up of more than 20 years were retrospectively studied (68 survived patients and 80 dead patients). The neurological evaluation was graded using Japanese Orthopaedic Association (JOA) score and the recovery rate. Neurological recovery was defined by the increase in JOA score. Radiological examinations were carried out using pre- and postoperative radiographs. As for the dead patients, the cause and age of death were reviewed.

RESULTS

The JOA score and recovery rate increased to 14.2 ± 2.7% and 64.9 ± 28.6%, respectively, at 5 years. The JOA score and recovery rate were maintained at 13.9 ± 3.2% and 61.6 ± 34.6% at 10 years. The JOA score decreased to 11.4 ± 5.1 at the last follow-up. In 32 out of 65 patients (49.2%), the JOA scores worsened mainly due to other spinal lesions. Cervical alignment became kyphotic when comparing preoperatively and at the last follow-up (ossification of the posterior longitudinal ligament: 15.7 ± 12.2° and 6.9 ± 17.8°, cervical spondylosis: 11.0 ± 8.9° and 3.3 ± 9.4°). Range of motion (ROM) decreased and one of the causes of ROM reduction was interlaminar fusion. The mean age at death was 78.2 years. The most frequent cause of death was malignant tumor.

CONCLUSION

Spine surgeons must be aware that patients have a long postoperative lifetime when cervical laminoplasty is performed. A long postoperative follow-up should be carried out after laminoplasty.

LEVEL OF EVIDENCE

4.

The Midterm Surgical Outcome of Modified Expansive Open-Door Laminoplasty

Laminoplasty is a standard technique for treating patients with multilevel cervical spondylotic myelopathy. Modified expansive open-door laminoplasty (MEOLP) preserves the unilateral paraspinal musculature and nuchal ligament and prevents facet joint violation. The purpose of this study was to elucidate the midterm surgical outcomes of this less invasive technique. We retrospectively recruited 65 consecutive patients who underwent MEOLP at our institution in 2011 with at least 4 years of follow-up. Clinical conditions were evaluated by examining neck disability index, Japanese Orthopaedic Association (JOA), Nurick scale, and axial neck pain visual analog scale scores. Sagittal alignment of the cervical spine was assessed using serial lateral static and dynamic radiographs. Clinical and radiographic outcomes revealed significant recovery at the first postoperative year and still exhibited gradual improvement 1–4 years after surgery. The mean JOA recovery rate was 82.3% and 85% range of motion was observed at the final follow-up. None of the patients experienced aggravated or severe neck pain 1 year after surgery or showed complications of temporary C5 nerve palsy and lamina reclosure by the final follow-up. As a less invasive method for reducing surgical dissection by using various modifications, MEOLP yielded satisfactory midterm outcomes.

Comparison of anterior decompression and fusion versus laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament: a systematic review and meta-analysis

Purpose

A meta-analysis was conducted to evaluate the clinical outcomes, complications, reoperation rates, and late neurological deterioration between anterior decompression and fusion (ADF) and laminoplasty (LAMP) in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

All related studies published up to August 2015 were acquired by searching PubMed and EMBASE. Exclusion criteria were case reports, revision surgeries, combined anterior and posterior surgeries, the other posterior approaches including laminectomy or laminectomy and instrumented fusion, non-English studies, and studies with quality assessment scores of <7. The main end points including Japanese Orthopedic Association (JOA) score, recovery rate of JOA, cervical lordosis, complication rate, reoperation rate, and late neurological deterioration were analyzed. All available data was analyzed using RevMan 5.2.0 and Stata 12.0.

Results

A total of seven studies were included in the meta-analysis. The mean surgical level of ADF was 3.1, and the mean preoperative occupation ratios of ADF and LAMP group were 55.9% and 51.9%, respectively. No statistical difference was observed with regard to preoperative occupation ratio and preoperative JOA score. Although LAMP group had a higher preoperative cervical lordosis than ADF group (P<0.05, weighted mean difference [WMD] =−5.73, 95% confidence interval [CI] =−9.67–−1.80), significantly decreased cervical lordosis was observed in LAMP group after operation. ADF group had higher postoperative JOA score (P<0.05, WMD =2.18, 95% CI =0.98–3.38) and neurological recovery rate (P<0.05, WMD =27.22, 95% CI =15.20–39.23). Furthermore, ADF group had a lower late neurological deterioration rate than the LAMP group (P<0.05, risk difference =0.16, 95% CI =0.04–0.73). The complication rates of both groups had no statistical difference. However, LAMP group had a significantly lower reoperation rate than ADF group. The reoperation rate of ADF group (20.5%) was almost six times that of LAMP group (3.5%).

Conclusion

Our meta-analysis suggested that ADF was associated with better postoperative neurological function, neurological recovery rate, and less late neurological deterioration than LAMP in the treatment of multilevel cervical OPLL with a high mean occupation ratio. LAMP was associated with a decreased postoperative cervical lordosis, which might be a cause of late neurological deterioration. The complication rates of both groups showed no statistical difference. However, the reoperation rate was significantly higher in ADF group compared with LAMP group. Benefits and risks should be balanced when ADF or LAMP is selected.

Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy Undergoing Unilateral Open-Door Laminoplasty

Objective

This study aimed to analyze prognostic factors affecting surgical outcomes of expansive laminoplasty for cervical spondylotic myelopathy (CSM).

Methods

Using the Frankel scale and Japanese Orthopaedic Association (JOA) scale, we retrospectively reviewed the outcomes of 45 consecutive patients who underwent modified unilateral open-door laminoplasty using hydroxyapatite spacers and malleable titanium miniplates between June 2008 and May 2014. The patients were assigned to the good and poor clinical outcome groups, with good outcome defined as a JOA recovery rate >75%.

Results

The mean preoperative JOA scale was significantly higher in the good outcome group (14.95±3.21 vs. 10.78±6.07, p<0.001), whereas the preoperative cervical range of motion (ROM) in this group was significantly lower (29.89°±10.11 vs. 44.35°± 8.88, p<0.001). In univariate analysis, a high preoperative JOA scale (odds ratio (OR) 1.271, 95% confidence interval (CI) 1.005-1.607) and low preoperative cervical ROM(OR 0.858, 95% CI 0.786-0.936) were statistically correlated with good outcomes. Furthermore, these factors demonstrated an independent association with clinical outcomes (preoperative JOA scale: OR 1.344, 95% CI 1.019-1.774, p=0.036; preoperative cervical ROM: OR 0.860, 95% CI 0.788-0.940, p=0.001).

Conclusion

In this study, a high preoperative JOA scale was associated with good clinical outcome after laminoplasty, whereas a higher preoperative cervical spine ROM was associated with poor clinical outcome. This may suggests that cervical mobility and preoperative neurological status affect clinical outcomes of laminoplasty.

Significance of Intramedullary High Signal Intensity on Magnetic Resonance Imaging in Patients with Cervical Ossification of the Posterior Longitudinal Ligament

BACKGROUND

The purpose of this study was to analyze the relation between intramedullary high signal intensity (IMHS) on magnetic resonance imaging (MRI), radiographic parameters, and clinical symptoms in cervical ossification of the posterior longitudinal ligament (OPLL) patients.

METHODS

Two hundred forty-one patients, who underwent simple radiography, computed tomography (CT), and MRI were included in the present study. As radiographic parameters, the OPLL occupying ratio and occupying area were measured on CT images. Dynamic factors were assessed by measuring cervical range of motion (ROM) on simple radiographs. Visual analog scale (VAS) for neck and arm pain, and Japanese Orthopaedic Association (JOA) scores were evaluated for clinical analysis. The differences in radiographic and clinical findings were assessed between patients with IMHS on T2-weighted MRI findings (group A) and patients without IMHS (group B).

RESULTS

Eighty-one patients were assigned to group A and 160 patients to group B. The occupying ratios were found to be higher in group A than in group B on both sagittal and axial views (p < 0.01). Group A also showed a higher area occupying ratio (p < 0.01). The length and area of underlying spinal canal on the sagittal and cross-sectional planes were lower in group A than in group B (p < 0.01). No significant difference in ROM was observed (p = 0.63). On the clinical findings, group A had a lower JOA score (p < 0.001), and no intergroup differences in VAS scores were observed.

CONCLUSIONS

In cervical OPLL cases, IMHS on MRI was associated with manifestation of myelopathic symptom. Occupying ratio was associated with high signal intensity on MRI, whereas no association was found with ROM. Occurrence of high signal intensity increased inversely with the length and area of underlying spinal canal.

Influence of sagittal and axial types of ossification of posterior longitudinal ligament on mechanical stress in cervical spinal cord: A finite element analysis

BACKGROUND

There are few studies focusing on the prediction of stress distribution according to the types of ossification of the posterior longitudinal ligament, which can be fundamental information associated with clinical aspects such as the relationship between stress level and neurological symptom severity. In this study, the influence of sagittal and axial types of ossification of the posterior longitudinal ligament on mechanical stress in the cervical spinal cord was investigated.

METHODS

A three-dimensional finite element model of the cervical spine with spinal cord was developed and validated. The von Mises stresses in the cord and the reduction in cross-sectional areas and volume of the cord were investigated for various axial and sagittal types according to the occupying ratio of ossification of the posterior longitudinal ligament in the spinal canal.

FINDINGS

The influence of axial type was less than that of the sagittal type, even though the central type showed higher maximum stresses in the cord, especially for the continuous type. With a 60% occupying ratio of ossification of the posterior longitudinal ligament, the maximum stress was significantly high and the cross-sectional area of the spinal cord was reduced by more than 30% of the intact area regardless of sagittal or axial types. Finally, a higher level of sagittal extension would increase the peak cord tissue stress, which would be related to the neurological dysfunction and tissue damage.

INTERPRETATION

Quantitative investigation of biomechanical characteristics such as mechanical stress may provide fundamental information for pre-operative planning of treatment for ossification of the posterior longitudinal ligament.

Surgical Outcome for Hemodialysis-Related Upper Cervical Lesions

STUDY DESIGN

A retrospective study.

PURPOSE

To investigate the surgical outcome for hemodialysis-related upper cervical lesions.

OVERVIEW OF LITERATURE

Surgical outcome of lower cervical lesions in patients undergoing hemodialysis has been reported. However, surgical outcome for upper cervical lesions in hemodialysis patients is unclear.

METHODS

Upper cervical lesions in nine patients undergoing hemodialysis were surgically treated. Mean age at surgery was 61.6 years (range, 52-68 years), and the mean follow-up period was 45.4 months (range, 2-98 months). Patients had undergone hemodialysis for an average of 25.3 years (range, 16-40 years) at surgery. Seven patients with destructive spondyloarthropathy (DSA) of the upper cervical spine were treated with atlantoaxial or occipitocervical fixation. Two patients with retro-odontoid pseudotumors were treated with C1 posterior arch resection alone. Japanese Orthopedic Association (JOA) scores for cervical myelopathy, postoperative complications, postoperative radiography, and preoperative and postoperative occipital pain were evaluated.

RESULTS

Mean preoperative and postoperative JOA score was 3.7 and 8.1, respectively. The seven patients with DSA had severe preoperative occipital pain that disappeared postoperatively. Postoperative radiography showed solid bone union in DSA cases and no instability in pseudotumor cases.

CONCLUSIONS

Satisfactory surgical outcome was observed for hemodialysis-related upper cervical lesions.

Cervical open-door laminoplasty technique with simple sutures and bone grafts: a single institutional study with 30 consecutive cases

Background

Expansive open-door laminoplasty is widely accepted as a reliable procedure for cervical myelopathy. However, one acknowledged complication is spring-back complication or closure of the door which may result in restenosis of cervical canal and neurologic deterioration. The study aimed for addressing our cervical open-door laminoplasty technique with sutures and bone grafts and subsequently the follow-up outcomes.

Methods

Thirty consecutive patients who underwent open-door laminoplasty with the novel technique were included and followed for minimum 5 years from Jan 2006 to Dec 2007. Anteroposterior diameter (APD) of the vertebral canal of C4 was measured in lateral cervical radiographs. Neurologic scenarios were noted using the Japanese Orthopaedic Association (JOA) scores.

Results

Twenty-five males (83.3%) and five (16.7%) females with an average follow-up of 68 months were enrolled. The preoperative APD was 13.22 mm (±1.15), whereas the postoperative APD increased to 31.23 mm (±2.43) with an expansion ratio of 136.23% (P < 0.05). The JOA score increased from 8.5 preoperatively to 13.45 postoperatively with a recovery rate of 58.2% (P < 0.05). The elevated laminas were maintained open during the follow-up period.

Conclusions

Our technique with sutures and bone graft for laminoplasty is a simple and efficient method for maintaining the decompression of cervical canal and neurologic improvement.

Open-door versus French-door laminoplasty for the treatment of cervical multilevel compressive myelopathy

Open-door laminoplasty (ODL) and French-door laminoplasty (FDL) are used to treat cervical multilevel compressive myelopathy. However, differences in outcome between the approaches remain unknown. To investigate treatment differences, we performed a systematic review and meta-analysis. Four comparative trials were identified and analyzed in the review. The results showed that ODL had a higher postoperative Japanese Orthopaedic Association (JOA) score than FDL (weighted mean difference [WMD]=0.83; 95% confidence interval [CI]: 0.47 to 1.19; p<0.01). There were no significant differences between the two methods in terms of operative time (WMD=-6.76; 95% CI: -21.70 to 8.18; p=0.38), intraoperative blood loss (WMD=41.70; 95% CI: -61.43 to 144.82; p=0.43), total complication rate (OR=2.43, 95% CI: 0.22 to 27.04; p=0.47), postoperative C5 palsy (OR=1.97, 95% CI: 0.46 to 8.39; p=0.36), postoperative cervical lordosis (WMD=-0.60; 95% CI: -0.37 to 1.86; p=0.63) or range of motion (WMD=-4.62; 95% CI: -13.06 to 3.82; p=0.28). These results suggest that neither cervical laminoplasty approach is superior to the other based on the postoperative radiological data and complication rate, although ODL had higher postoperative JOA score than FDL.

The impact of dynamic factors on surgical outcomes after double-door laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine

OBJECT

Laminoplasty is the preferred operation for most patients with cervical myelopathy due to multilevel ossification of the posterior longitudinal ligament (OPLL). Recent studies have demonstrated several significant risk factors for poor clinical outcomes after laminoplasty, including older age, lower preoperative Japanese Orthopaedic Association (JOA) score, postoperative change in cervical alignment, cervical kyphosis, and high occupying ratio of the OPLL (that is, the ratio of the greatest anteroposterior thickness of the OPLL to the anteroposterior diameter of the spinal canal at the same level on a lateral image). However, the impact of dynamic factors on clinical outcomes is unclear. The purpose of this study is to assess the impact of dynamic factors on the clinical outcome after laminoplasty for cervical myelopathy due to OPLL.

METHODS

A consecutive series of patients who underwent laminoplasty for cervical myelopathy due to OPLL between 2003 and 2009 was retrospectively reviewed. The indication for laminoplasty at the authors' hospital included preoperative straight or lordotic alignment of the cervical spine and an occupying ratio of OPLL less than 60%. The JOA score and recovery rate were used to evaluate clinical outcomes. A poor clinical outcome was defined as a recovery rate of less than 50%. Patient factors examined along with outcome included age, preoperative JOA score, preoperative somatosensory evoked potentials, preoperative motor evoked potentials, body mass index, and presence of high intensity on MRI. Radiographic measures included the preoperative C2-7 lordotic angle, preoperative C2-7 range of motion (ROM), preoperative segmental ROM at the level of myelopathy, and the occupying ratio of OPLL.

RESULTS

There were 45 patients (33 males and 12 females). The mean follow-up period was 4 years (range 2-6.8 years). The mean patient age was 66.9 years (range 50-85 years). The mean JOA score significantly increased from 9.1 before surgery to 13.1 at the final follow-up. The mean recovery rate was 51.2%. Nineteen patients (42%) had a recovery rate of less than 50%. Patient factors were not associated with surgical outcomes. Only the preoperative C2-7 ROM was significantly greater in the poor surgical outcome group (23.1° vs 14.1°). Receiver operating characteristic curve analysis showed that the optimal preoperative C2-7 ROM cutoff was 20°. Logistic regression analysis revealed that patients with a preoperative C2-7 ROM of greater than 20° had a 4.6 times higher risk (p = 0.021) of a poor clinical outcome, indicating that dynamic factors may have an impact on the surgical outcome of laminoplasty.

CONCLUSIONS

Fusion surgery may be a useful strategy in patients with preoperative hypermobility of the cervical spine.

Is there a difference in range of motion, neck pain, and outcomes in patients with ossification of posterior longitudinal ligament versus those with cervical spondylosis, treated with plated laminoplasty?

OBJECT

There are little data on the effects of plated, or plate-only, open-door laminoplasty on cervical range of motion (ROM), neck pain, and clinical outcomes. The purpose of this study was to compare ROM after a plated laminoplasty in patients with ossification of posterior longitudinal ligament (OPLL) versus those with cervical spondylotic myelopathy (CSM) and to correlate ROM with postoperative neck pain and neurological outcomes.

METHODS

The authors retrospectively compared patients with a diagnosis of cervical stenosis due to either OPLL or CSM who had been treated with plated laminoplasty in the period from 2007 to 2012 at the University of California, San Francisco. Clinical outcomes were measured using the modified Japanese Orthopaedic Association (mJOA) scale and neck visual analog scale (VAS). Radiographic outcomes included assessment of changes in the C2-7 Cobb angle at flexion and extension, ROM at C2-7, and ROM of proximal and distal segments adjacent to the plated lamina.

RESULTS

Sixty patients (40 men and 20 women) with an average age of 63.1 ± 10.9 years were included in the study. Forty-one patients had degenerative CSM and 19 patients had OPLL. The mean follow-up period was 20.9 ± 13.1 months. The mean mJOA score significantly improved in both the CSM and the OPLL groups (12.8 to 14.5, p < 0.01; and 13.2 to 14.2, respectively; p = 0.04). In the CSM group, the mean VAS neck score significantly improved from 4.2 to 2.6 after surgery (p = 0.01), but this improvement did not reach the minimum clinically important difference (MCID). Neither was there significant improvement in the VAS neck score in the OPLL group (3.6 to 3.1, p = 0.17). In the CSM group, ROM at C2-7 significantly decreased from 32.7° before surgery to 24.4° after surgery (p < 0.01). In the OPLL group, ROM at C2-7 significantly decreased from 34.4° to 20.8° (p < 0.01). In the CSM group, the change in the VAS neck score significantly correlated with the change in the flexion angle (r = - 0.31) and the extension angle (r = - 0.37); however, it did not correlate with the change in ROM at C2-7 (r = - 0.1). In the OPLL group, the change in the VAS neck score did not correlate with the change in the flexion angle (r = 0.03), the extension angle (r = - 0.17), or the ROM at C2-7 (r = - 0.28). The OPLL group had a significantly greater loss of ROM after surgery than did the CSM group (p = 0.04). There was no significant correlation between the change in ROM and the mJOA score in either group.

CONCLUSIONS

Plated laminoplasty in patients with either OPLL or CSM decreases cervical ROM, especially in the extension angle. Among patients who have undergone laminoplasty, those with OPLL lose more ROM than do those with CSM. No correlation was observed between neck pain and ROM in either group. Neither group had a change in neck pain that reached the MCID following laminoplasty. Both groups improved in neurological function and outcomes.

Dynamic changes in spinal cord compression by cervical ossification of the posterior longitudinal ligament evaluated by kinematic computed tomography myelography

STUDY DESIGN

A prospective clinical study.

OBJECTIVE

To investigate the dynamic causative factor in the pathogenesis of myelopathy in patients with cervical ossification of the posterior longitudinal ligament (OPLL) using kinematic computed tomography (CT) myelography.

SUMMARY OF BACKGROUND DATA

Kinematic CT myelography is useful for dynamically evaluating the cervical spine with high-resolution images, particularly in bony compressive lesions. However, no studies have evaluated the dynamic factors in patients with OPLL using kinematic CT myelography.

METHODS

From 2008 to 2013, 51 consecutive patients with OPLL who presented with myelopathy were prospectively enrolled in this study. The patients were examined with kinematic (flexion-extension) CT myelography using a multidetector CT scanner. The range of motion at C2-C7 from flexion to extension was measured in the sagittal view. The segmental range of motion, anterior-posterior diameter and cross-sectional area (CSA) of the spinal cord were measured at the level where the spinal cord was most compressed by OPLL.

RESULTS

The neurological condition of the patients evaluated by Japanese Orthopaedic Association scores were 10.8 ± 2.4 points. The mean range of motion at C2-C7 and at the most compressed segment were 23.1 ± 11.7 and 7.0 ± 4.4°, respectively. Both the anterior-posterior diameter and the CSA at the most compressed levels were significantly decreased during neck extension compared with flexion. Interestingly, the anterior-posterior diameter and the CSA were decreased during neck flexion in 13.7% (7/51) of the patients. All 7 of these patients had massive OPLL with an occupying rate 60% or more. The dynamic change rate of CSA (flexion/extension) was significantly smaller in patients with an OPLL occupying rate 60% or more compared with patients with an occupying rate less than 60%.

CONCLUSION

Although spinal cord compression was increased during neck extension in most of the patients, greater levels of compression could be placed on the spinal cord during neck flexion when the patients had OPLL with a high occupying rate.

LEVEL OF EVIDENCE

4.

Long-term results of cervical myelopathy due to ossification of the posterior longitudinal ligament with an occupying ratio of 60% or more

STUDY DESIGN

Retrospective study.

OBJECTIVE

We sought to determine the long-term outcomes of laminoplasty versus anterior decompression and fusion in the treatment of cervical myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) and to ascertain what factors should be considered in selecting appropriate surgical procedure.

SUMMARY OF BACKGROUND DATA

There are little data about long-term results of cervical myelopathy due to OPLL with an occupying ratio 60% or more.

METHODS

We retrospectively studied 27 patients having OPLL with an occupying ratio 60% or more and a follow-up period of at least 2 years. Clinical outcome was evaluated using Japanese Orthopaedic Association scores and recovery rates (≥75%, excellent; 50%-74%, good; 25%-50%, fair; and <25%, poor).

RESULTS

The mean age and the mean duration of follow-up were 57 years and 10.2 years. The mean Japanese Orthopaedic Association score was 9.3 before surgery and 12.4 at the final follow-up examination. There were 15 patients in the laminoplasty group (LAM group) and 12 patients in the anterior decompression and fusion group (ADF group). The ADF group had a significantly better recovery rate at final evaluation (53% vs. 30%; P = 0.04), a longer duration of surgery (314 vs. 128 min; P < 0.01), and greater blood loss (600 vs. 240 mL; P < 0.01) than did the LAM group. In the LAM group, 4 patients with excellent or good results had a significantly larger degree of cervical lordosis (30°vs. 10°; P = 0.002) than others.

CONCLUSION

The ADF group had a significantly better recovery rate than the LAM group, although the degree of surgical invasiveness was high. ADF is generally recommended for OPLL with an occupying ratio 60% or more.

LEVEL OF EVIDENCE

3.

Predictive factors affecting outcome after cervical laminoplasty

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine whether various preoperative factors affect patient outcome after cervical laminoplasty for cervical spondylotic myelopathy (CSM) and/or ossification of posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty is a procedure designed to decompress the spinal cord by enlarging the spinal canal while preserving the lamina. Prior research has identified a variety of potential predictive factors that might affect outcomes after this procedure.

METHODS

A systematic search of multiple major medical reference databases was conducted to identify studies explicitly designed to evaluate the effect of preoperative factors on patient outcome after cervical laminoplasty for CSM or OPLL. Studies specifically designed to evaluate potential predictive factors and their associations with outcome were included. Only cohort studies that used multivariate analysis, enrolled at least 20 patients, and adjusted for age as a potential confounding variable were included. JOA (Japanese Orthopaedic Association), modified JOA, and JOACMEQ-L (JOA Cervical Myelopathy Evaluation Questionnaire lower extremity function section) scores were the main outcome measures. Clinical recommendations and consensus statements were made through a modified Delphi approach by applying the GRADE (Grading of Recommendation Assessment, Development and Evaluation)/AHRQ (Agency for Healthcare Research and Quality) criteria.

RESULTS

The search strategy yielded 433 citations, of which 1 prospective and 11 retrospective cohort studies met our inclusion criteria. Overall, the strength of evidence from the 12 studies is low or insufficient for most of the predictive factors. Increased age was not associated with poorer JOA outcomes for patients with CSM, but there is insufficient evidence to make a conclusion for patients with OPLL. Increased severity of disease and a longer duration of symptoms might be associated with JOA outcomes for patients with CSM. Hill-shaped lesions might be associated with poorer JOA outcomes for patients with OPLL. There is insufficient evidence to permit conclusions regarding other predictive factors.

CONCLUSION

Overall, the strength of evidence for all of the predictive factors was insufficient or low. Given that cervical myelopathy due to CSM tends to be progressive and that increased severity of myelopathy and duration of symptoms might be associated with poorer outcomes after cervical laminoplasty for CSM, it is preferable to perform laminoplasty in patients with CSM earlier rather than waiting for symptoms to get worse. Further research is needed to more clearly identify predictive factors that affect outcomes after cervical laminoplasty because there were relatively few studies identified that used multivariate analyses to control for confounding factors and many of these studies did not provide a detailed description of the multivariate analyses or the magnitude of effect estimates. EVIDENCE-BASED CLINICAL RECOMMENDATIONS:

RECOMMENDATION 1

For patients with CSM, increased age is not a strong predictor of clinical neurological outcomes after laminoplasty; therefore, age by itself should not preclude cervical laminoplasty for CSM.

OVERALL STRENGTH OF EVIDENCE

Low.

STRENGTH OF RECOMMENDATION

Strong.

RECOMMENDATION 2

For patients with CSM, increased severity of disease and a longer duration of symptoms might be associated with poorer clinical neurological outcomes after laminoplasty; therefore, we recommend that patients be informed about this.

OVERALL STRENGTH OF EVIDENCE

Low.

STRENGTH OF RECOMMENDATION

Strong. SUMMARY STATEMENTS: For patients with OPLL, hill-shaped lesions might be associated with poorer clinical neurological outcomes after laminoplasty; therefore, surgeons might consider potential benefits and risks of alternative or additional surgery.

Long-term outcomes of 2 cervical laminoplasty methods: midline splitting versus unilateral single door

BACKGROUND

Two major current methods are midline splitting laminoplasty (MSL) and unilateral single-door laminoplasty (USDL). Few studies have compared the 2 techniques.

METHODS

We retrospectively analyzed the outcomes of 100 consecutive myelopathy patients who underwent decompressive laminoplasty between January 2004 and June 2008. The mean follow-up duration was 48.2 months.

RESULTS

The mean Japanese Orthopedic Association scores changed from 6.9 to 11.9 in the MSL group and from 6.2 to 12.4 in the USDL group, resulting in mean calculated recovery rates of 55.5% and 63.0%, respectively (P = 0.14). Mean cervical lordosis declined from 12.0 to 10.2 degrees in the MSL group and from 10.3 to 8.5 degrees in the USDL group (P = 0.24). Mean cervical range of motion declined from 27.8 to 25.6 degrees in the MSL group, and from 23.4 to 16.0 degrees in the USDL group (P = 0.38). Bony spinal canal dimension increased from 201.2 to 280.8 mm in the MSL group and from 204.3 to 331.7 mm in the USDL group (P < 0.001). In the USDL group, 6 patients experienced postoperative neck pain, 7 experienced C5 palsy, and 2 experienced cerebrospinal fluid leakage. No such complications occurred in the MSL group (P ≥ 0.05 for both complications).

CONCLUSIONS

MSL and USDL patients had similar long-term clinical and radiologic outcomes, except that bony canal expansion was greater in the latter. We believe that removal of the ligamentum flavum and drilling of the internal bony edge were factors in the favorable clinical outcomes and low rate of complications in the MSL group.