Incidence of heterotopic ossification following total hip arthroplasty by approach: a systematic review.

Background: Heterotopic ossification (HO) formation has been increasingly recognized as a complication of major orthopedic surgeries, particularly total hip arthroplasty (THA). Though, the overall incidence of HO following THA has been well-documented, it is often not reported by severity or by surgical approach.

Questions/purposes: (1) What are the demographics of patients with HO? (2) What is the severity of HO following THA using the Brooker classification? (3) What is the incidence and class of HO following different THA approaches (anterior, posterior, posterolateral, anterolateral, superior, lateral, trans-gluteal)? (4) What are the number and training level of surgeons who performed each procedure?

Methods: The PubMed, Embase, and Web of Science databases were queried, and PRISMA guidelines were followed. Qualitative and quantitative analyses were performed using Microsoft Excel.

Results: We isolated 26 studies evaluating 6512 total hip arthroplasties (THA). The mean HO percentage overall was 28.8%, mostly Class I (54.2%) or Class II (29.6%). The highest percentage of HO was associated with the modified direct lateral (57.2%) and the traditional lateral (34.6%) approaches. The lowest HO percentages were identified following posterolateral (12.8%) and direct superior approaches (1%). Most studies reported a singular senior surgeon operating within the same approach for all patients.

Conclusions: The traditional lateral and modified direct lateral approaches to THA resulted in the highest percentage of HO postoperatively. However, most ossification cases were not clinically significant and did not strongly affect overall patient morbidity. Further studies are warranted to identify an association between severity of ossification and different arthroplasty approaches.