Efficacy of the RIMAG unconventional hip prosthesis in patients with primary bone tumors, metastasis and non-tumor osteoarticular losses

To assess the functional efficacy of the RIMAG unconventional hip prosthesis in cancer and non-cancer patients. Functional analysis of 38 patients with RIMAG arthroplasty, using the Musculoskeletal Tumor Society Scoring System and including the following: functionality versus histologic diagnosis (5 malignancies, 3 metastases, 14 giant cell tumors (GCT), 8 with other benign tumors, and 8 had no tumor), age (40.4 +/- 19.1 years), sex (24 females, 14 males), postoperative follow-up (34.7 +/- 31.3 months). Analysis of intraoperative, immediate and late complications, time to weight bearing, gait and work or social reintegration were also assessed. Global mean of ideal functionality was 65.6 +/- 23.2%. Age was negatively correlated with the functionality rate (r = -0.507, p = 0.001); significant difference with the histologic diagnosis: malignant tumors 54.8, metastasis 58.6, giant cell tumor 25.6, other benign tumors 34.2, non-tumor causes 56.6 (p = 0.001). When functionality means were adjusted for age with a covariance analysis, better percentages were found for benign tumors (79.2 +/- 6.8%) and giant cell tumors (76.4 +/- 6.3%), less functionality for non-tumor causes (45.7 +/- 7.6%), and intermediate percentages for malignant tumors and metastasis (p = 0.03). Intraoperative complications occurred in 4 cases (28.6%), immediate in 3 (7.8%), late in 15 (39.4%); 62.5% of patients started immediate weight bearing, 92.1% resumed their usual activities after surgery. The reconstruction of the proximal femur with RIMAG is a safe and reliable treatment option, with complication rates below the ones reported in the literature. Satisfactory results were obtained, with high functional rates for benign tumors, and low rates in older patients, malignant tumors and metastasis.