Incidence and risk factors for heterotopic ossification after total hip arthroplasty: a meta-analysis

This study aims to quantitatively summarize risk factors associated with heterotopic ossification after total hip arthroplasty. The computerized and additional manual searches were performed in Medline, Embase, CNKI, and Cochrane central database (all through March 2014) for potential studies. Studies eligible had to meet the quality assessment criteria by Newcastle-Ottawa Scale and to evaluate the risk factors for heterotopic ossification after total hip arthroplasty. Two reviewers independently extracted the relevant data and any disagreement was solved by consensus. Stata11.0 was used to perform all the statistical analyses. Fourteen studies involving 6468 cases with total hip arthroplasty and 1939 heterotopic ossification (HOs) (30.0 %) were eligible and included in this meta-analysis. Our meta-analysis identified the significant increased risk factors for HO were male gender [odds ratio (OR) 2.11; 95 % confidence interval (CI) 1.80-2.48)], cemented implant (OR 1.48; 95 % CI 1.00-2.17), bilateral operations (OR 1.74; 95 % CI 1.24-2.45), ankylosing spondylitis (OR 1.90; 95 % CI 1.07-3.37) and ankylosed hip (OR 9.85; 95 % CI 2.61-37.24). Rheumatoid arthritis was protective for the development of HO (OR 0.51; 95 % CI 0.33-0.80). The other variables including age, use of NSAIDs, femoral neck fracture, previous hip fracture, hypertrophic osteoarthritis and osteophytes were identified not as the risk factors for development of HO (P > 0.05). Patients involved with the above-mentioned medical conditions should be carefully paid close attention by surgeons to reduce HO after total hip arthroplasty. Level II, meta-analysis.