The characteristics and predictors of mortality in periprosthetic fractures around the knee.

Aims: Periprosthetic fractures (PPFs) around the knee are challenging injuries. This study aims to describe the characteristics of knee PPFs and the impact of patient demographics, fracture types, and management modalities on in-hospital mortality. Methods: Using a multicentre study design, independent of registry data, we included adult patients sustaining a PPF around a knee arthroplasty between 1 January 2010 and 31 December 2019. Univariate, then multivariable, logistic regression analyses were performed to study the impact of patient, fracture, and treatment on mortality. Results: Out of a total of 1,667 patients in the PPF study database, 420 patients were included. The in-hospital mortality rate was 6.4%. Multivariable analyses suggested that American Society of Anesthesiologists (ASA) grade, history of peripheral vascular disease (PVD), history of rheumatic disease, fracture around a loose implant, and cerebrovascular accident (CVA) during hospital stay were each independently associated with mortality. Each point increase in ASA grade independently correlated with a four-fold greater mortality risk (odds ratio (OR) 4.1 (95% confidence interval (CI) 1.19 to 14.06); p = 0.026). Patients with PVD have a nine-fold increase in mortality risk (OR 9.1 (95% CI 1.25 to 66.47); p = 0.030) and patients with rheumatic disease have a 6.8-fold increase in mortality risk (OR 6.8 (95% CI 1.32 to 34.68); p = 0.022). Patients with a fracture around a loose implant (Unified Classification System (UCS) B2) have a 20-fold increase in mortality, compared to UCS A1 (OR 20.9 (95% CI 1.61 to 271.38); p = 0.020). Mode of management was not a significant predictor of mortality. Patients managed with revision arthroplasty had a significantly longer length of stay (median 16 days; p = 0.029) and higher rates of return to theatre, compared to patients treated nonoperatively or with fixation. Conclusion: The mortality rate in PPFs around the knee is similar to that for native distal femur and neck of femur fragility fractures. Patients with certain modifiable risk factors should be optimized. A national PPF database and standardized management guidelines are currently required to understand these complex injuries and to improve patient outcomes.

Characteristics and risk factors of UCS fracture subtypes in periprosthetic fractures around the hip.

Aims: Periprosthetic fractures (PPFs) following hip arthroplasty are complex injuries. This study evaluates patient demographic characteristics, management, outcomes, and risk factors associated with PPF subtypes over a decade. Methods: Using a multicentre collaborative study design, independent of registry data, we identified adults from 29 centres with PPFs around the hip between January 2010 and December 2019. Radiographs were assessed for the Unified Classification System (UCS) grade. Patient and injury characteristics, management, and outcomes were compared between UCS grades. A multinomial logistic regression was performed to estimate relative risk ratios (RRR) of variables on UCS grade. Results: A total of 1,104 patients were included. The majority were female (57.9%; n = 639), ethnically white (88.5%; n = 977), used mobility aids (67%; n = 743), and had a median age of 82 years (interquartile range (IQR) 74 to 87). A total of 77 (7%) had pain prior to the PPF. The most common UCS grade was B2 (33%; n = 368). UCS type D fractures had the longest length of stay (median 19 days (IQR 11 to 26)), highest readmission to hospital (21%; n = 9), and highest rate of discharge to step-down care (52%; n = 23). Multinomial regression suggests that uncemented femoral stems are associated with a reduced risk of UCS C (RRR 0.36 (95% confidence interval (CI) 0.2 to 0.7); p = 0.002) and increased risk of UCS A (RRR 3.3 (95% CI 1.9 to 5.7); p < 0.001), compared to UCS B fracture. Conclusion: The most common PPF type in elderly frail patients is UCS B2. Uncemented stems have a lower risk of UCS C fractures compared to cemented stems. A national PPF database is needed to further identify correlation between implants and fracture subtypes.