Periprosthetic fractures of hip and knee-A morbidity and mortality analysis

Periprosthetic fractures (PPF) following total knee (TKA) and hip arthroplasty (THA) have become more common over the years. The aim of the present study was to assess morbidity and mortality following surgery for PPF of hip and knee.

Altogether, 124 patients (mean age: 77 years; 77.4% female) with PPF of the hip (n=97) and knee (n=27), treated between 2005 and 2017 at a level-1 trauma centre, were retrospectively included. In order to assess risk factors for postoperative morbidity, Fine and Gray's model was used to compensate for death as the competing event. Risk factors for mortality were estimated with uni- and multivariate Cox-regression models.

Vancouver B2 fractures were most common (n=39; 42.4%), followed by B1 fractures (n=23; 25.0%). Lewis-Rorabeck Type I fractures (n=14; 51.9%) were most frequent in PPF of the knee. Overall complication rates were 44.0% and 29.9% for PPF of the knee and hip, respectively, with three patients having both early and late complications, 25 patients developing early complications and 19 patients undergoing surgery for implant-related, late complications. In the multivariate Fine and Gray model, advanced patient age (HR: 0.956; 95%CI: 0.922-0.991; p=0.014) and prosthesis exchange (vs. ORIF; HR: 0.242, 95%CI: 0.068-0.859; p=0.028) were associated with lower risk of implant-related complications, irrespective of gender (p=0.450) and a surgical delay > 2 days (p=0.411). One- and 5-year overall survival-rates were 97.9% and 93.1%, respectively. Gender, type of fixation (ORIF vs. prosthesis exchange), surgical delay > 2 days, BMI and age at surgery were neither in the univariate, nor multivariate Cox-regression model associated with an increased mortality rate.

Postoperative morbidity caused by implant-related complications is higher in younger patients and those receiving ORIF. With the statistical approach used, potential underestimation of actual complication rates may have been avoided, taking into account death as the competing event. Despite being based on a retrospective, heterogenous patient collective treated at a level-1 trauma centre, our results indicate that careful planning of the surgical procedure beyond 2 days, taking into consideration both patient's age and activity level, has no negative effect on patient outcome.