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

BACKGROUND: 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. METHODS: 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. - RESULTS: 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. CONCLUSIONS: 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.