BACKGROUND

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in the world. The optimal surgical approach for treating CSM is not known. For over 60 years, there has been active debate advocating either ventral or dorsal surgical approaches for treating CSM. Most agree that decompression of the spinal cord and fusion of the spinal column results in clinical improvement; however, clinical improvement does not occur in up to 30% of treated patients. Furthermore, complications of surgery are common and differ among the various surgical approaches. There is global variation in how cervical myelopathy is treated. From a clinical effectiveness and safety perspective, there is an urgent need to determine which procedure (ie, ventral or dorsal) is more effective and in which type of patient with cervical myelopathy.

OBJECTIVES

The Cervical Spondylotic Myelopathy–Surgical (CSM-S) trial was a randomized prospective study conducted to compare the effectiveness of a ventral vs dorsal approach to surgery for patients with multilevel CSM. Another goal of the study was to compare dorsal laminoplasty (DL) with ventral fusion (VF) and dorsal fusion (DF) strategies in a nonrandomized comparison. The trial consisted of 3 specific aims to test the following: 1a.. Whether ventral surgery is associated with superior Physical Component Summary (PCS) scores of the Short-Form Health Survey-36 (SF-36) at 1-year follow-up compared with dorsal (DF or DL) surgery. 1b.. Compared with preoperative baseline status, whether both ventral and dorsal surgery for CSM improve symptoms of spinal cord dysfunction using the modified Japanese Orthopaedic Association (mJOA) score. 2.. From a patient perspective, whether health resource use (out-of-pocket expenses and loss of productivity) for VF, DF, and DL surgery are different. 3.. Whether cervical sagittal balance postoperatively is a significant predictor of SF-36 PCS score outcome.

METHODS

We conducted a multicenter prospective randomized controlled trial with patients aged 45 to 80 years with multilevel CSM. Patients were screened and enrolled over a 4-year period (2014-2018) from 16 sites. Patients were randomly assigned to ventral or dorsal surgery (2:3 randomization); the dorsal surgical approach (DF or DL) was at the discretion of surgeon and patient (ie, not randomly assigned). The primary outcome measure was the SF-36 PCS score. A clinically meaningful difference in SF-36 PCS scores is defined as 5 points. Secondary outcome assessments (Neck Disability Index [NDI], mJOA, and EuroQol-5 Dimension [EQ-5D]), along with patient work status, were obtained preoperatively, 3 months, 6 months, and 1 year postoperatively. Complications were assessed by an independent study coordinator, who was blinded to other outcome data at 1 month and at 1 year postoperatively. Health resource use was measured using patient health diaries.

RESULTS

A total of 16 sites randomly assigned 163 patients: 63 (38.7%) were randomly assigned to ventral surgery and 100 (61.3%) to dorsal. Average age was 62 years and 49% were male. Baseline characteristics were comparable between ventral and dorsal groups. After random assignment there was a 3.1% crossover rate. A total of 155 (95%) patients provided 1-year follow-up. There were 2.8 levels of spinal canal stenosis in patients enrolled in the study with no significant differences at baseline among the groups. Analysis as randomized demonstrated no difference in improvement in SF-36 PCS score at 1 year between ventral and dorsal surgery (5.90 ventral vs 6.22 dorsal; mean difference = 0.32; 95% CI, −2.62 to 3.26; = .8372). We conducted a planned analysis of patients as treated. Sixty-six patients ultimately underwent VF and 97 underwent dorsal surgery (69 DF and 28 DL). Regardless of strategy, patients demonstrated significant change from baseline in NDI (14.6 VF, 10.4 DF, 17.7 DL), mJOA (2.2 VF, 1.9 DF, 2.4 DL), and EQ-5D scores (0.14 VF, 0.12 DF, 0.19 DL) over a 1-year period postoperatively. DL had a superior primary outcome, the SF-36 PCS score (9.78), compared with VF (5.74; mean difference = 4.04; 95% CI, 0.13-7.95, = .043) and DF (4.99; mean difference = 4.78; 95% CI, 0.13-9.44; = .044). Patients undergoing VF and DF surgeries experienced a greater number of complications at 1 month postoperatively than did patients undergoing DL (42.4% VF vs 27.5% DF vs 10.7% DL; = .007). At 1 year, the proportion of patients working before surgery (68/163) who returned to work was similar among the 3 groups (85.2% VF vs 75.9% DF vs 90.9% DL).

CONCLUSIONS

Overall, patients with CSM randomly assigned to a ventral vs dorsal approach had similar 1-year outcomes. Compared with patients who had VF (n = 66) or DF (n = 69), the subgroup of patients, who at the discretion of the surgeon had DL (n = 28), experienced greater improvement in health-related quality of life, fewer complications, and less ongoing outpatient physical therapy and opioid usage at 1 year.

LIMITATIONS

The comparison of laminoplasty with DF or VF is limited by the potential for confounding by indication. Although baseline characteristics, including levels of spinal cord compression, were similar among all 3 surgical cohorts, there might have been anatomical features that influenced the choice of surgical approach (DF vs DL) that also influenced study outcomes independently of whether dorsal patients had laminoplasty or laminectomy with fusion (confounding by indication).