Interscapular Pain after Anterior Cervical Discectomy and Fusion: Does Zygapophyseal Joints over Distraction Play a Role?

Introduction: Anterior cervical discectomy and fusion (ACDF) for cervical disc herniation (CDH) is commonly performed. Specific post-operative complications include dysphagia, dysphonia, cervicalgia, adjacent segment disorder, cage subsidence, and infections. However, interscapular pain is commonly reported by these patients after surgery, although its mechanisms have not been clarified yet. Methods: This retrospective series of 31 patients undergoing ACDF for CDH at a single Academic Hospital. Baseline and post-operative clinical, radiological, and surgical data were analyzed. The linear regression analysis was conducted to identify any factor independently influencing the incidence rate of post-operative interscapular pain. Results: The mean age was 57.6 ± 10.8 years, and the M:F ratio was 2.1. Pre-operative mean VAS-arm was 7.15 ± 0.81 among the 20 patients reporting brachialgia, and mean VAS-neck was 4.36 ± 1.43 among those 9 patients reporting cervicalgia. At 1 month, interscapular pain was still reported by 8 out of the 17 patients who experienced it post-operatively, and it was recovered in all patients after 2 months. The regression analysis showed that interscapular pain was not directly associated with age (p = 0.74), gender (p = 0.46), smoking status (p = 0.44), diabetes (0.42), pre-operative brachialgia (p = 0.21) or cervicalgia (p = 0.48), symptoms duration (p = 0.13), baseline VAS-arm (p = 0.11), VAS-neck (p = 0.93), or mJOA (p = 0.63) scores, or disc height modification (p = 0.90). However, the post-operative increase in the mean zygapophyseal joint rim distance was identified as an independent factor in determining interscapular pain (p = 0.02). Conclusions: Our study revealed that the onset of interscapular pain following ACDF may be determined by over distraction of the zygapophyseal joint rim. Then, proper sizing of prosthetic implants could reduce this painful complication.