Comparison of Heterotopic Ossification After Fixed- and Mobile-Core Cervical Disc Arthroplasty.

OBJECTIVE: To compare the heterotopic ossification (HO) between cervical disc arthroplasty (CDA) with fixed- and mobile-core prosthesis and to compare the clinical and radiographic outcomes.

METHODS: This was a retrospective analysis of patients who underwent CDA in our institute. Patients were divided into a fixed-core group (Prodisc-C and Discover disc) and mobile-core group (Bryan and Prestige-LP disc). HO was assessed based on the McAfee classification. The visual analogue scale, Neck Disability Index, and Japanese Orthopaedic Association scores were used to evaluate clinical outcomes. In addition, radiographic assessments included cervical sagittal alignment (C2-C7 angle), segmental angle, and range of motion of the index level.

RESULTS: A total of 218 patients were included with a minimal follow-up of 24 months. There were 137 patients in mobile-core group (Prestige-LP, 102; Bryan, 35) and 81 patients in the fixed-core group (Discover, 43; and Prodisc-C, 38). The mean follow-up time was 46.8 months. At the final follow-up, the overall incidence of HO was 39.9%. The incidence of HO in the fixed-core group was significantly greater than that in the mobile-core group (50.6% vs. 33.6%, P = 0.013). However, there were no significant differences in visual analogue scale, Neck Disability Index, or Japanese Orthopaedic Association scores, C2-C7 angle, segmental angle, or range of motion of the index level between the 2 groups.

CONCLUSIONS: The fixed-core prosthesis had a greater incidence of HO than mobile-core prosthesis after CDA. However, both CDA with fixed- and mobile-core prostheses obtained good clinical outcomes and maintained cervical sagittal alignment.