Time to surgery and other risk factors for mortality and complication rates in patients with periprosthetic femoral fractures at the knee.

Background: There is a high level of evidence that a short time to surgery (TTS) improves the outcome for patients with hip fractures. Accordingly, recommendations for timely treatment have been included in national guidelines. As patient characteristics appear to be similar, it seems reasonable that these guidelines are applicable to other fracture entities, such as knee periprosthetic femoral fracture (PPF). This monocentric retrospective study aimed to investigate outcome-related risk factors, particularly TTS, for knee PPF.

Methods: In total, 141 consecutive patients with knee PPF in a maximum-care arthroplasty and trauma centre, treated between 2006 and 2020, were retrospectively evaluated. Primary outcome variables were operative and general complications as well as mortalities within 1 year. Outcome-related risk factors were identified based on regression analysis using SPSS. For analysis of TTS, the cases were divided into two groups using a TTS of 24 h as the cutoff value.

Results: The 1-year mortality was 8.3 %. Associated risk factors were age (HR 1.2; p = 0.010) and Charlson score (HR 2.1; p = 0.001). Both, surgical and general complications occurred in 20.6 % of the cases. Age (OR 1.07, p = 0.025) and a TTS > 24 h (OR 3.06, p = 0.020) were identified as risk factors for general complications. The TTS ≤ 24 h (n = 75) and TTS > 24 h (n = 66) groups were comparable in terms of baseline characteristics. Revision arthroplasty was performed more frequently in the TTS > 24 h group (p < 0.001).

Conclusion: 1-year mortality after knee PPF was 8.3 %. With a high complication rate in the treatment of knee PPF, TTS was identified as a risk factor for general complications. Early treatment appears to be beneficial for patients with knee PPF.