Modular megaprostheses yield high any-type failure rate but acceptable infection control rate in patients with chronic hip and knee periprosthetic joint infection and severe bone loss: a single-center experience

Chronic periprosthetic joint infections (PJIs) complicated by severe bone loss are challenging cases that require complex and specialized treatment approaches. Megaprosthetic replacement has gained in popularity in the setting of chronic hip and knee PJI; however, only a limited number of studies reporting on its utility are available. Thus, we aimed to review our cohort of patients with this specific condition who received modular megaprosthesis (MMP) as a limb salvage option in order to assess the failure rates, infection control, and implant longevity. We retrospectively reviewed electronic medical records of 61 patients who received MMPs for chronic hip and knee PJI between 2012 and 2024. The mean follow-up was <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>6.6</mml:mn> <mml:mo>±</mml:mo> <mml:mn>3.5</mml:mn></mml:mrow> </mml:math> years. Failures were classified according to the Henderson classification. Kaplan-Meier survival curves were used to assess failure-free, infection-free, and overall implant survival. Cox regression analysis was performed to identify variables associated with MMP failure. Among the 61 patients, 37.7 % experienced any type of MMP failure, with infection recurrence being the most common reason for failure (60.9 %), followed by structural failure of the implant (17.4 %). At the 5-year follow-up, failure-free survival, infection-free survival, and revision-free survival were 65.8 %, 80.0 %, and 70.5 %, respectively. McPherson host grade C was significantly associated with implant failure (hazard ratio (HR) 3.1; 95 % confidence interval 1.4-7.6; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>P</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.024</mml:mn></mml:mrow> </mml:math> ). Conclusively, MMPs represent a valuable treatment option for patients with chronic hip and knee PJI and large bone defects. While infection control is acceptable, the rates of any-type failure are high. These findings should be considered during preoperative patient counseling.