Sagittal Alignment After Laminectomy Without Fusion as Treatment for Cervical Spondylotic Myelopathy: Follow-up of Minimum 4 Years Postoperatively

Cervical kyphosis after posterior cervical laminectomy with and without fusion

BACKGROUND

Cervical posterior instrumentation and fusion is often performed to avoid post-laminectomy kyphosis. However, larger comparative analyses of cervical laminectomy with or without fusion are sparse.

METHODS

A retrospective, two-center, comparative cohort study included patients after stand-alone dorsal laminectomy with (n = 91) or without (n = 46) additional fusion for degenerative cervical myelopathy with a median follow-up of 59 (interquartile range (IQR) 52) months. The primary outcome was the C2-7 Cobb angle and secondary outcomes were Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA) scale, revision rates, T1 slope and C2-7 sagittal vertical axis (C2-7 SVA) at final follow-up. Logistic regression analysis adjusted for potential confounders (i.e. age, operated levels, and follow-up).

RESULTS

Preoperative C2-7 Cobb angle and T1 slope were higher in the laminectomy group, while the C2-7 SVA was similar. The decrease in C2-7 Cobb angle from pre- to postoperatively was more pronounced in the laminectomy group (- 6° (IQR 20) versus -1° (IQR 7), p = 0.002). When adjusting for confounders, the decrease in C2-7 Cobb angle remained higher in the laminectomy group (coefficient - 12 (95% confidence interval (CI) -18 to -5), p = 0.001). However, there were no adjusted differences for postoperative NDI (- 11 (- 23 to 2), p = 0.10), mJOA, revision rates, T1 slope and C2-7 SVA.

CONCLUSION

Posterior cervical laminectomy without fusion is associated with mild loss of cervical lordosis of around 6° in the mid-term after approximately five years, however without any clinical relevance regarding NDI or mJOA in well-selected patients (particularly in shorter segment laminectomies of < 3 levels).

MRI-based measurements of spondylolisthesis and kyphosis in degenerative cervical myelopathy

BACKGROUND

To provide normative data and to determine accuracy and reliability of preoperative measurements of spondylolisthesis and kyphosis on supine static magnetic resonance imaging (MRI) of patients with degenerative cervical myelopathy.

METHODS

T2-weighted midsagittal images of the cervical spine were in 100 cases reviewed twice by one junior observer, with an interval of 3 months, and once by a senior observer. The spondylolisthesis slip (SSlip, mm) and the modified K-line interval (mK-line INT, mm) were assessed for accuracy with the standard error of measurement (SEm) and the minimum detectable change (MDC). Intraobserver and interobserver reliability levels were determined using the intraclass correlation coefficient (ICC).

RESULTS

The SEm was 0.5 mm (95% CI 0.4-0.6) for spondylolisthesis and 0.6 mm (95% CI 0.5-0.7) for kyphosis. The MDC, i.e., the smallest difference between two examinations that can be detected with statistical certainty, was 1.5 mm (95% CI 1.2-1.8) for spondylolisthesis and 1.6 mm (95% CI 1.3-1.8) for kyphosis. The highest reliability levels were seen between the second observation of the junior examiner and the senior observer (ICC = 0.80 [95% CI 0.70-0.87] and ICC = 0.96 [95% CI 0.94-0.98] for SSlip and mK-line INT, respectively).

CONCLUSIONS

This study provides normative values of alignment measurements of spondylolisthesis and kyphosis in DCM patients. It further shows the importance of taking measurement errors into account when defining cut-off values for cervical deformity parameters and their potential clinical application in surgical decision-making.

Cervical alignment and clinical outcome of open-door laminoplasty vs. laminectomy and instrumentation in kyphotic multilevel cervical degenerative myelopathy

INTRODUCTION

The aim of this study was to determine whether the sagittal lordotic alignment, clinical outcomes and axial symptoms (AS) could be improved by kyphotic correction through the posterior approach for the treatment of multilevel cervical degenerative myelopathy (CDM) and to further analyze the changes of cervical spinal alignment parameters after correction of kyphosis. The hypothesis was that correction of kyphosis can improve the severity of AS and neurological recovery.

MATERIALS AND METHODS

We retrospectively reviewed 109 patients who suffered from multilevel CDM combined with kyphosis. The patients had undergone open-door laminoplasty (Group LP, 53 patients) and laminectomy with instrumentation (Group LI, 56 patients) between January 2014 and December 2018. Cervical spinal alignment parameters, including curvature index (CI), T1 slope, C2-7 Cobb angle, C2-7 SVA, were measured on the pre- and postoperative lateral radiographs. The recovery rate was calculated based on the Japanese Orthopedic Association (JOA) score. AS severity was quantified using Neck Disability Index (NDI). A P value less than 0.05 was considered to be significant.

RESULTS

Analyses of postoperative follow-up data showed significant differences (P < 0.001) in CI, correction of CI, C2-7 Cobb angle, T1 slope, C2-7 SVA and NDI between Group LP and LI, but no significant differences in JOA score (P = 0.23) and recovery rate (P = 0.13). There were significant differences (P < 0.001) in CI, T1 slope, C2-7 Cobb angle, C2-7 SVA, JOA score, and NDI between pre- and postoperative follow-up in both groups. Correction of CI showed negative correlation with AS severity (r = -0.51, P < 0.001), and no association with recovery rate (r = 0.14, P = 0.15).

CONCLUSIONS

Satisfied neurological improvement was achieved by LP and LI for multilevel CDM combined with kyphosis. Cervical kyphotic correction produced significant improvement of AS and increase of T1 slope and C2-7 SVA. However, the kyphotic correction may not be associated with better neurological recovery in the short-term postoperative period.

Long-Term Follow-Up After Cervical Laminectomy without Fusion for Cervical Spondylotic Myelopathy

OBJECTIVE

The objectives were to study the effect of cervical laminectomy without fusion on the incidence of further cervical surgeries, the risk for cervical misalignment, and current functional status.

METHODS

We retrospectively analyzed the clinical data of 340 patients who had undergone simple laminectomy for cervical spondylotic myelopathy (CSM) at Helsinki University Hospital between 2000 and 2011.

RESULTS

Forty-one patients (12.1%) had later undergone another cervical surgery during the follow-up of a mean of 8.5 years (maximum, 17.5 years). The most common indication for further surgery was residual stenosis at adjacent or other cervical levels (34%). Five patients (1%) required further surgery for correction of a sagittal balance problem. The mean Neck Disability Index was 28% at a median of 9.0 years after laminectomy. The mean EQ-5D (EuroQol 5 Dimension 3 Level) index score was 58.8 for patients and 77.2 for age-matched and gender-matched general population controls (P = 0.000), indicating patients' reduced health-related quality of life. Worse preoperative condition in the Nurick score was related to a lower (i.e., worse) EQ-5D score. In an additional arm of the study with radiographic imaging (40 patients), the mean change in sagittal alignment was 4.0° toward lordotic, and a newly developed kyphosis was found in 7.5% of patients.

CONCLUSIONS

Because CSM is a serious degenerative progressive condition resulting in decreased health-related quality of life even after surgical treatment, the low rate of corrective surgery needed for alignment issues per se indicates that simple laminectomy can be a viable treatment option in treating multilevel CSM.

Effectiveness of laminectomy with fusion and laminectomy alone in degenerative cervical myelopathy

PURPOSE

The effectiveness of laminectomy with fusion and laminectomy alone in degenerative cervical myelopathy was compared.

METHODS

Individuals treated with laminectomy with fusion or laminectomy alone at or below the second cervical vertebra were identified in the Swedish spine registry. 66 individuals treated with laminectomy and instrumented fusion were age matched to 132 individuals treated with laminectomy alone. The European Myelopathy Scale (EMS), the Neck Disability Index (NDI), the Numeric Rating Scale (NRS) for neck pain and the EQ-5D index were available at baseline, and at 1 and 2 year follow-ups. Statistical analyses were performed with Mann-Whitney U tests and paired T tests. Effect sizes were described with Cohen's D.

RESULTS

Data at baseline did not differ significantly between the groups with the exception of a longer laminectomy in the fusion group (4.2 vs 3.4 vertebras; p < 0.001). Both groups improved EMS, NDI, NRS and EQ-5D from baseline to 1 year (p ≤ 0.011), with no additional improvement between 1 and 2 years (all p ≥ 0.09). Effect sizes for change from baseline were small to medium in both groups. At 2 years the laminectomy with fusion group and the laminectomy alone group had a median (25th;75th percentile) EMS of 13 (11;13) and 13 (11;15) (p = 0.77), NDI of 39 (24;54) and 27 (10;41) (p = 0.045), NRS of 4 (1;2) and 2 (0;5) (p = 0.048), and EQ-5D index of 0.67 (0.25;0.73) and 0.66 (0.17;0.76) (p = 0.96).

CONCLUSION

The results of this study suggest similar effectiveness of laminectomy with instrumented fusion and laminectomy alone in degenerative cervical myelopathy.

LEVEL OF EVIDENCE

III.

Comparative outcome analysis of lateral mass fixation and trans-facet fixation with posterior decompression in the management of cervical spondylotic myelopathy: An institutional experience

Aims and Objectives

Posterior subaxial cervical fusion with lateral mass screw and rod instrumentation is a well-established fixation technique. Subaxial transarticular facet fixation is a lesser known fusion technique that has been shown to be biomechanically equivalent to lateral mass screws. The aim of this study was to evaluate the outcome of cervical decompressive laminectomy with lateral mass fixation compared with decompressive laminectomy with trans-facet fixation.

Materials and Methods:

The study was conducted with 20 patients operated for cervical decompressive laminectomy with lateral mass fixation compared with 20 patients operated with trans-facet fixation. The modified Japanese orthopedic association score (mJOA) scale, Nurick's functional grading and neurological recovery rate (NRR) was used as the functional outcome measurement. The clinical follow-up period was 6 months.

Results:

In Group I, the mean preoperative and postoperative mJOA scores in Group I and II were 8.2 ± 2.1 and 12.7 ± 2.8 and 9.3 ± 1.9 and 13.5 ± 1.88, respectively, were statistically significant (P < 0.05). Postoperative NRR at the end of the follow-up period was satisfactory (excellent and good) 55% in Group I and 60% in Group II. Fusion was documented in all 40 patients. No patients experienced neural or vascular injury as a result of screw position.

Conclusions:

Both trans-facet and lateral mass fixation techniques are simple, safe, and effective procedures in achieving relief and improvement in patients with multilevel cervical spondylotic myelopathy. Trans-facetal fixation can provide a reasonable alternative to lateral mass fixation.

Association between pre-operative sagittal alignment and radiographic measures of decompression following cervical laminectomy: a retrospective cohort study

Background

The primary purpose of this study was to determine the association between pre-operative cervical sagittal alignment and the extent of cord decompression in the form of increased spinal cord width and cerebrospinal fluid (CSF) space in front of and behind the cord in patients undergoing laminectomy for cervical spondylotic myelopathy (CSM). Secondary objectives included an assessment of the correlation between increasing numbers of levels decompressed and the post-operative cervical spine sagittal alignment, the effect of laminectomy on the change in alignment, as well as effect of laminectomy on pre-existing spinal cord signal abnormality.

Methods

This retrospective cohort study included patients who underwent cervical laminectomies, without fusion, between 2015 and 2020. Chart review was used to collect baseline variables. Cervical sagittal alignment, width of the spinal cord, and the CSF space in-front and behind the cord was measured pre-operatively and post-operatively using magnetic resonance imaging (MRI) scans for each patient. The correlation between change in measured parameters and pre-operative cervical sagittal alignment was assessed using Spearman's correlation.

Results

Thirty-five patients were included. Average age was 65.29±10.98 years old. The majority of patients (80%) underwent laminectomies at 3-4 levels. Average pre-operative sagittal alignment determined by the Cobb angle was 6.05°±14.17°, while the average post-operative Cobb angle was 3.15°±16.64°. The change in Cobb angle was not statistically significant (P=0.998). Eleven patients (32%) had pre-operative kyphotic sagittal alignment. The average time from surgery to post-operative MRI scan was 20.44±13.18 months (range, 3-39; median, 18.5; IQR, 23.5). There was no statistically significant association between increasing levels of decompression and change in alignment (P=0.546). Cord signal abnormality persisted after decompression. There was a moderate correlation between lordotic pre-operative cervical sagittal alignment and change in space in-front of the cord (correlation coefficient 0.337, P=0.048) and change in cord width (correlation coefficient 0.388, P=0.021).

Conclusions

Severity of pre-operative kyphotic sagittal alignment is associated with decreased spinal cord drift and extent of decompression. The pre-operative sagittal alignment is not significantly associated with the change in post-operative alignment. Increasing number of levels decompressed does not worsen a kyphotic cervical spine sagittal alignment.