Periprosthetic Fractures of the Acetabulum: A Rare, but Serious Complication of Total Hip Arthroplasty

BACKGROUND: Periprosthetic acetabular fractures in the postoperative period are a relatively rare complication of total hip arthroplasty (THA). There are limited data describing this patient population, their treatment, and outcomes. METHODS: A retrospective review was conducted using a prospectively gathered database of 3,595 revision THA procedures from 1990 to 2024. Of these, 54 periprosthetic acetabular fractures were identified. The review was performed to determine patient demographics, implant survivorship, mortality, and functional outcomes. RESULTS: A total of 54 periprosthetic fractures of the acetabulum were identified in patients who had a mean age of 74 years, an American Society of Anesthesiologists class of 3.1, and a follow-up of 22 months (range, one to 121). Pelvic discontinuity was present in 59.3%. Osteolysis contributed to the fracture in 51.9% and was the principal cause in 33.3%. Treatment was with a cup-cage construct (51.9%), a cage alone (22.2%), or a trabecular metal cup alone (25.9%). The overall complication rate was 37.0%, with 60.0% of these requiring reoperations (22.2% overall). The most common complications included infection (18.5%), sciatic nerve injury (5.6%), and fracture (3.7%). The 30-day mortality was 3.7%. Survivorship due to all-cause failure was 82.1% at one year, 70.5% at two years, and 51.4% at three years. Survivorship due to failure excluding infection was 95.2% at one year, 84.7% at two years, and 84.7% at three years. At the last follow-up, 88.1% were ambulatory, with 45.9% using a walker, 24.3% a cane, and 29.7% without aids. CONCLUSIONS: Periprosthetic acetabular fractures are a rare, but challenging complication of THA. Complication rates are high, and early revision of periacetabular osteolysis may help prevent the development of major fractures. To our knowledge, this is the largest series described in the literature, providing key prognostic information. Further prospective studies are needed to optimize treatment of these challenging fractures.