The incidence of postoperative heterotopic ossification in cervical disc arthroplasty--A systematic review and meta-analysis

Abstract Background: Heterotopic ossification has become a common disease after CDA, which has attracted much attention. Understanding the law of its occurrence and development can provide theoretical basis for the formulation of HO prevention strategies. To acquire the objective data and the change rule of HO incidence, a meta-analysis of all available evidence was performed. Methods: A search of the literature was conducted on Pubmed/MEDLINE, EMBASE, and Web of Science. Relevant studies including incidence-relative data of HO were selected according to eligibility criteria. Results: 52 studies were eligible and finally included and the quality assessment showed a relative high score of them. The results of the analysis reminded us that the incidence of HO increased with the extension of follow-up time, both based on the number of cases and the number of segments, and the increase mainly occurred after 6 years. Grade III-IV HO showed us a positive correlation with follow-up time (R2=0.218), while Grade I-II HO did not change a lot in different follow-up time points. Conclusions: The follow-up time after CDA should be long enough, so as to ensure the true clinical results. HO occurs all the postoperative time and Grade I-II HO will gradually develop into Grade III-IV, while continuous new HO keeps the number of Grade I-II in a dynamic balance. Through this study, we can preliminarily define the relatively objective incidence and change rule of HO, which provides data basis and theoretical basis for the future research of HO prevention strategy.