Complications and functional evaluation of 17 saddle prostheses for resection of periacetabular tumors

Seventeen saddle prostheses were inserted between 1988 and 1997 after resection of periacetabular tumors. The tumors involved the zones II and III of Enneking classification in 13 patients, the zones I and II in 2 patients, and the zone II in 2 patients. The tumors included 11 chondrosarcomas, 3 Ewing sarcomas, 2 giant cells tumors, and 1 metastasis of renal carcinoma. The tumoral resection was wide "en bloc" in 14 cases, marginal in 2 cases, and intratumoral in 1 case. The mean follow-up period of the patients is 42 months ranging from 8 to 84 months. Local recurrences occurred in five cases and metastases in four cases. Five patients died of tumoral disease and one of intercurrent disease. Complications were observed in 11 cases (65%) including nerve damages (3 cases), deep infections (3 cases), upward migrations of the saddle (4 cases), saddle dislocations (3 cases), sacroiliac subluxations (2 cases), and mechanical failures (2 cases). The modified Musculoskeletal Tumor Society Score (MSTS) and the Toronto Extremity Salvage Score (TESS) were used for functional analysis. Functional results were available for only nine patients of the series with a mean MSTS of 17 points ranging from 11 to 23 points and a mean TESS of 58 points ranging from 39 to 95 points. The saddle prosthesis provided in all cases of this series an early painfree weight-bearing reconstruction with minimal limb shortening, but the functional results remained fair in most patients due to a limited range of motion and a poor abductor strength.