Prevalence of heterotopic ossification after cervical total disc arthroplasty: a meta-analysis

Heterotopic ossification (HO) is a well-known complication after total hip and knee arthroplasty. But limited studies have focused on prevalence of HO following cervical total disc arthroplasty (CTDA) and the published data show controversial results. The purpose of this review is to investigate the prevalence of HO following CTDA by meta-analysis. The literatures were collected from PubMed, Embase and Cochrane library by using keywords as ([disc or disk] and [arthroplasty or replacement]) and (HO or delayed fusion or spontaneous fusion). The original studies were eligible only if the prevalence of HO and of advanced HO (Grade 3-4 according to McAfee) were investigated. A meta-analysis was then performed on collected data. Statistical heterogeneity across the various trials was tested using Cochran's Q, statistic and in the case of heterogeneity a random effect model was used. Tests of publication bias and sensitivity analysis were also performed. Our data showed that the pooled prevalence of HO was 44.6% (95% confidence interval (CI), 37.2-45.6%) 12 months after CTDA and 58.2% (95% CI, 29.7-86.8%) 24 months after CTDA, while the advanced HO was 11.1% (95% CI, 5.5-16.7%) and 16.7% (95% CI, 4.6-28.9%), respectively. A significant heterogeneity was obtained. There was no publication bias and individual study had no significant effect on the pooled prevalence estimate. Higher prevalence of HO was observed following CTDA, although HO was reported to be unrelated to the clinical improvement. It suggests that cervical disc replacement should be performed cautiously before obtaining long-term supporting evidence. Prognostic level III.