Is Gender a Factor Affecting Long-Term Heterotopic Ossification Incidence After Single-Level Cervical Disc Arthroplasty?

Abstract

Cervical disc diseases have been treated by cervical disc arthroplasty (CDA). Nevertheless, some patients will experience a mobility failure in their cervical prostheses over time because of heterotopic ossification. The aim of this study was to investigate the role of gender in long-term outcomes after CDA. A retrospective, single-center study of patients who underwent single-level CDA with a BRYAN Cervical Disc prosthesis was performed, including a narrative review about gender differences in both structural and biomechanical features of the cervical spine. Study patients (14 men, 30 women) had an average follow-up of 9.8 ± 3.2 years. Significant differences emerged between genders for specific items in Neck Disability Index preoperative evaluation, with women reporting worse pain scores (P= 0.05). After stratification by age, we found a higher preoperative overall Neck Disability Index score for female patients <36 years of age (P= 0.03). In an intergender, body mass index-specific comparison, we also found a significant difference in Neck Disability Index preoperative score with normal-weight male patients faring worse than overweight male patients (P= 0.05). At a radiological level, we found a tendency toward a higher heterotopic ossification incidence in male patients (62% in men, 17% in women, P= 0.06). The female cervical spine has distinctive features, including bone structure, muscular action, soft tissue response, and genetic and epigenetic response to osteoarthritis. The incidence of mobility failure in our series of single-level CDA was lower in female patients. Several gender-specific factors both in static and in dynamic features may play a significant role in spinal pathology and CDA long-term radiological outcome.