A comparison of minimally invasive posterior cervical decompression and open anterior cervical decompression and instrumented fusion in the surgical management of degenerative cervical myelopathy.

OBJECTIVE Minimally invasive posterior cervical decompression (miPCD) has been described in several case series with promising preliminary results. The object of the current study was to compare the clinical outcomes between patients undergoing miPCD with anterior cervical discectomy and instrumented fusion (ACDFi). METHODS A retrospective study of 74 patients undergoing surgery (45 using miPCD and 29 using ACDFi) for myelopathy was performed. Outcomes were categorized into short-term, intermediate, and long-term follow-up, corresponding to averages of 1.7, 7.7, and 30.9 months, respectively. Mean scores for the Neck Disability Index (NDI), neck visual analog scale (VAS) score, SF-12 Physical Component Summary (PCS), and SF-12 Mental Component Summary (MCS) were compared for each follow-up period. The percentage of patients meeting substantial clinical benefit (SCB) was also compared for each outcome measure. RESULTS Baseline patient characteristics were well-matched, with the exception that patients undergoing miPCD were older (mean age 57.6 ± 10.0 years [miPCD] vs 51.1 ± 9.2 years [ACDFi]; p = 0.006) and underwent surgery at more levels (mean 2.8 ± 0.9 levels [miPCD] vs 1.5 ± 0.7 levels [ACDFi]; p < 0.0001) while the ACDFi patients reported higher preoperative neck VAS scores (mean 3.8 ± 3.0 [miPCD] vs 5.4 ± 2.6 [ACDFi]; p = 0.047). The mean PCS, NDI, neck VAS, and MCS scores were not significantly different with the exception of the MCS score at the short-term follow-up period (mean 46.8 ± 10.6 [miPCD] vs 41.3 ± 10.7 [ACDFi]; p = 0.033). The percentage of patients reporting SCB based on thresholds derived for PCS, NDI, neck VAS, and MCS scores were not significantly different, with the exception of the PCS score at the intermediate follow-up period (52% [miPCD] vs 80% [ACDFi]; p = 0.011). CONCLUSIONS The current report suggests that the optimal surgical strategy in patients requiring dorsal surgery may be enhanced by the adoption of a minimally invasive surgical approach that appears to result in similar clinical outcomes when compared with a well-accepted strategy of ventral decompression and instrumented fusion. The current results suggest that future comparative effectiveness studies are warranted as the miPCD technique avoids instrumented fusion.

The effect of minimally invasive dorsal cervical decompression for myelopathy on spinal alignment and range of motion.

OBJECTIVE: Minimally invasive dorsal cervical decompression (miDCD) has been reported as a novel alternative to open dorsal decompression techniques such as laminectomy, laminoplasty, or laminectomy and fusion. Only limited data have been presented regarding the effects of a minimally invasive approach on cervical motion and alignment. The object of the current study is to provide a more comprehensive analysis of radiographic outcomes following miDCD. PATIENTS AND METHODS: Thirty-five patients who had undergone miDCD for myelopathy were included. Exclusion criteria included prior cervical spine surgery, prior cervical spine fracture, fusion of the cervical spine during miDCD, and/or acute spinal cord injury. Analysis of x-rays included the following data elements: degrees of flexion, degrees of extension, and total range of motion; C2-C7 angle as a measure of cervical lordosis; C2-C7 sagittal vertical axis; effective lordosis; and C7 slope. Patient reported outcome measures included neck Visual Analog Score (VAS), Neck Disability Index (NDI), SF-12 Physical Component Score (PCS), SF-12 Mental Component Score (MCS), Nurick score, and modified Japanese Orthopedic Association Myelopathy scale (mJOA). RESULTS: Pre-operative to post-operative comparisons of all radiographic parameters - including total range of motion, C2-C7 Cobb angle, C2-C7 sagittal vertical axis, effective lordosis, and C7 slope angle - remained stable. Several clinical outcomes demonstrated statistical improvement, namely neck VAS, Nurick score, mJOA, NDI, and SF-12 PCS. CONCLUSIONS: miDCD can maintain cervical range of motion and alignment better than traditional laminectomy or laminoplasty techniques.

The effect of length of follow-up on substantial clinical benefit thresholds in patients undergoing surgery for cervical degenerative myelopathy.

Patient-reported outcome measures are increasingly used to access pain, disability, physical function, and mental status to quantify effectiveness of surgical intervention in cervical myelopathy, yet each score has little meaning without established thresholds linked to clinical benefit. We set out to develop thresholds for substantial clinical benefit (SCB) in patients undergoing surgery for cervical myelopathy and to evaluate the effect of length of follow-up on SCB thresholds. Thirty-five patients undergoing spinal surgery for progressive cervical myelopathy were tracked from 2005 to 2015. Observations were categorized into three groups: short-term, intermediate, and long-term, corresponding to average follow-up intervals of 3.8, 9.2, and 29.0 months. SCB thresholds were calculated for neck visual analog score (VAS), Neck Disability Index (NDI), Short Form-12 physical (PCS), SF-12 mental component scores (MCS), and modified Japanese Orthopedic Association score (mJOA) using receiver operating curve analysis with a 5-level patient satisfaction index as the anchor. SCB thresholds for each outcome measure were obtained with a range of areas under the curve indicating varying degrees of discriminatory ability, reported with increasing length of follow-up. NDI and PCS were most discriminatory of SCB at any time period. Stratification of thresholds by length of time revealed a significant effect of follow-up time with NDI but not PCS. NDI and PCS thresholds have significantly strong discriminatory value in identifying patients receiving substantial clinical benefit with regard to cervical myelopathy. When NDI is used to predict outcome, choosing thresholds calibrated for follow-up time is recommended to maximize predictive power.