Incidence of heterotopic ossification in direct anterior vs posterior approach to total hip arthroplasty: a retrospective radiographic review.

PURPOSE: To investigate the prevalence of heterotopic ossification following direct anterior approach total hip arthroplasty compared to posterior approach, performed by a single surgeon at one institution

METHODS: All primary THAs performed by the senior author (JEL) over a 70-month period were reviewed, including 235 DAA and 120 posterior THAs. Brooker's system was used to grade HO at a minimum of six months follow-up.

RESULTS: Patients undergoing DAA were less likely to develop clinically significant HO compared to posterior THA (p = 0.04). The overall incidence of HO following DAA THA was 24.3 % (3 % grade 3 and 0 % grade 4), and following posterior THA was 27.5 % (4.2 % grade 3 and 3.3 % grade 4).

CONCLUSIONS: Lower rates of clinically significant (Brooker grade 3 and 4) HO were observed in DAA THA than in posterior approach THA. This data may be instructive when approaching THA candidates with conditions that predispose them to HO.