The Survival Rate and Its Influencing Factors of Modular Endoprosthetic Replacement With Uncemented Stem for the Proximal Femur After Primary Tumor Resection.

Objective: Durable and biologically integrated fixation is critical for long-term implant survival in patients with primary bone tumors. However, limited evidence exists regarding the long-term outcomes of uncemented stem designs in this population. Specifically, we investigated: (1) the long-term patient and implant survivorship rates; (2) the influence of factors such as resection length and patient age on implant survival; and (3) the incidence and types of complications, particularly those requiring implant removal or revision.

Methods: We retrospectively reviewed 76 patients (49 males, 27 females; mean age 41 years, range 14-78 years) who underwent proximal femoral replacement with a modular uncemented endoprosthesis between 2015 and 2022. The mean follow-up was 63.4 months (median: 60.5 months; range: 12-104 months). Functional outcomes were assessed using the Musculoskeletal Tumor Society (MSTS) score, while complications were classified based on the Henderson et al. system. Survivorship analyses were conducted using Kaplan-Meier methods.

Results: The 5-year patient survival rate was 88.0%, and the 5-year implant survival rate was 90.4%. The mean MSTS score at final follow-up was 25.6 (range 16-30), with 87.7% of patients achieving good to excellent functional outcomes. Younger patients (< 30 years) exhibited poorer implant survival, while resection length did not significantly impact outcomes. Complications occurred in 18.4% of cases, categorized into type 1 (soft tissue-related, n = 3), type 2 (aseptic loosening, n = 2), type 3 (structural failure, n = 0), type 4 (infection, n = 3), type 5 (tumor recurrence, n = 3), and three cases of acetabular failure.

Conclusions: Modular uncemented endoprostheses for proximal femoral replacement demonstrated promising survivorship and functional outcomes in patients with primary bone tumors. The low rate of aseptic loosening highlights the benefits of uncemented stem designs. However, younger age remains a risk factor for reduced implant longevity.