Early loosening of the femoral stem in cemented segmental prostheses with distal femur replacement (DFR): a multicenter observational study

BACKGROUND: With the increasing prevalence of knee arthroplasty (TKA), the utilization of segmental prostheses with distal femur replacement (DFR) has expanded, particularly in revision surgeries. Concerns regarding early loosening of cemented femoral stems in these prostheses persist. QUESTIONS/PURPOSES: This study aimed to analyze the rate of early femoral component loosening and associated factors in DFR prostheses. PATIENTS AND METHODS: A retrospective multicenter study was conducted, including patients who underwent DFR with cemented stems between 2015 and 2019. Epidemiological variables and outcomes, including femoral component loosening and prosthetic replacement, were analyzed. Statistical methods included survival analysis and subgroup comparisons. RESULTS: Seventy patients were included, with a femoral component loosening rate of 15.7% within two years. Women exhibited a lower risk of loosening (OR 0.258, 95% CI 0.068-0.098, p = 0.038). Survival analysis showed no significant age-related differences (p = 0.064), but better survival was observed in women (p = 0.045). Previous canal cementation did not significantly affect loosening rates (p = 0.82). Reoperation rates were 24.3%, primarily for mechanical causes. CONCLUSIONS: Early loosening of cemented femoral stems in DFR prostheses is notable, emphasizing the need for enhanced fixation strategies, especially in patients with a history of femoral canal cementation. This study provides valuable insights into optimizing stem fixation systems and addressing concerns related to prosthetic survival.