Page 182 - Reconstructive Techniques in Musculoskeletal Tumor Surgery

Chapter 9
Abstract
Background: Modular endoprostheses are commonly used to reconstruct defects of the distal femur and proximal tibia after bone tumor resection. Because limb salvage surgery for bone sarcomas is relatively new, becoming more frequently used since the 1980s, studies focusing on the long-term results of such prostheses in treatment of primary tumors are scarce.
Questions / purposes: (1) What proportion of patients experience a mechanical complication with the MUTARS modular endoprosthesis when used for tumor reconstruction around the knee, and what factors may be associated with mechanical failure? (2) What are the non-mechanical complications? (3) What are the implant failure rates at ve, ten, and 15 years? (4) How often is limb salvage achieved using this prosthesis?
Methods: Between 1995 and 2010, endoprostheses were the preferred method of reconstruction after resection of the knee in adolescents and adults in our centers. During that period, we performed 114 MUTARS knee replacements in 105 patients; no other endoprosthetic systems were used. Four patients (four of 105 [4%]) were lost to follow-up, leaving 110 reconstructions in 101 patients for review. The reverse Kaplan-Meier method was used to calculate median follow-up, which was equal to 8.9 years (95% con dence interval [CI], 8.0 – 9.7). Mean age at surgery was 36 years (range, 13 – 82 years). Predominant diagnoses were osteosarcoma (n = 56 [55%]), leiomyosarcoma of bone (n = 10 [10%]), and chondrosarcoma (n = 9 [9%]). In the early period of our study, we routinely used uncemented uncoated implants for primary reconstructions. Later, hydroxyapatite (HA)-coated implants were the standard. Eighty-nine reconstructions (89 of 110 [81%]) were distal femoral replacements (78 uncemented [78 of 89 {88%}, 42 of which were HA- coated [42 of 78, 54%]) and 21 (21 of 110 [19%]) were proximal tibial replacements. In 26 reconstructions (26 of 110 [24%]), the reconstruction was performed for a failed previous reconstruction. We used a competing risk model to estimate the cumulative incidence of implant failure.
Results: Complications of soft tissue or instability occurred in seven reconstructions (seven of 110 [6%]). With the numbers we had, for uncemented distal femoral replacements, we could not detect a di erence in loosening between revision
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