Cervical orthosis does not improve postoperative pain following posterior cervical fusion: a randomized controlled trial.

Purpose: To determine whether postoperative neck pain in the first 4 weeks following multi-level posterior cervical fusion (PCF) with orthosis is equivalent to multi-level PCF without orthosis.

Methods: Patients were randomly assigned in a 1:1 ratio to postoperative orthosis (CO) for 6 weeks or no orthosis (NO). Randomization was stratified by indication (traumatic vs. degenerative), and preoperative opioid use. A model of longitudinal regression for repeated measures was used. The two-sided 95% confidence interval (CI) was used to test equivalence. If the CI lay between the pre-determined margin of equivalence (-2.0 to + 2.0 pain score) the two groups were considered equivalent. A multiple imputation procedure was used to replace missing data.

Results: Thirty-one patients were enrolled in each group. At baseline, the CO group had more neck pain (5.3 vs. 3.2, p = 0.013). The Four week post-operative neck pain intensity score was 4.6 ± 0.3 for the CO group vs. 4.9 ± 0.3 for the NO group. The 95% confidence interval (-1.2 to 0.6) was within the pre-determined equivalence margin. Neck Disability Index, quality-of-life scores, and arm pain were similar. Eleven patients in the CO group and 12 patients in the NO group had an adverse event. The CO group had reduced range of motion at 6 weeks.

Conclusion: Pain scores over the first 4 weeks after surgery were equivalent for patients undergoing multi-level PCF treated with or without a cervical orthosis. Our findings do not support the routine use of a postoperative cervical orthosis for postoperative pain control. Clinical Trials Registration Number NCT04308122, April 22, 2020.