Unrestricted weightbearing and ability to achieve postoperative ambulation after distal femur fracture fixation in elderly patients is not associated with decreased mortality

Purpose: The purpose of this study is to evaluate the association between 1) early postoperative mobilization on 30-day and 1-year mortality in patients ≥ 65 years who underwent fixation of distal femur fractures and 2) postoperative weightbearing instructions and early postoperative mobilization in this patient population. Methods: A multicentre, retrospective review of all patients ≥ 65 years of age who underwent operative fixation of a distal femur fracture between August 2012 and June 2023 at two academic level 1 trauma centres and one academic level 2 trauma centre was conducted. Univariate comparisons and binary logistic regression analyses were performed to identify factors associated with postoperative weightbearing instruction, postoperative mobilization, and mortality. Results: Three hundred and forty-seven patients were included in final analyses, with 347 patients included in the all-comer group and 274 patients included in the isolated distal femur fracture group. After adjusting for demographics and modified 5-factor frailty index (mFI-5) score, unrestricted postoperative weightbearing was associated with achievement of early postoperative mobilization in both the all-comer (p = 0.005, OR = 3.159 [95% CI 1.412–7.067]) and isolated fracture groups (p = 0.001, OR = 4.735 [95% CI 1.869–11.992]). Thirty-day mortality occurred in only 10 patients, therefore, analyses were not independently performed for this time point. After adjusting for demographics, mFI-5 score, and postoperative weightbearing instruction, postoperative mobilization was not associated with survival at one year in neither the all-comer (p = 0.281, OR = 0.589 [95% CI 0.225–1.542] nor isolated fracture groups (p = 0.432, OR = 0.664 [95% CI 0.240–1.841). Conclusion: Patients with unrestricted postoperative weightbearing instructions were more likely to achieve early postoperative mobilization; however, early mobilization after fixation of distal femur fractures in patients ≥ 65 years does not appear to correlate with 1-year mortality.