What Are the Long-term Results of MUTARS® Modular Endoprostheses for Reconstruction of Tumor Resection of the Distal Femur and Proximal Tibia?

Abstract

BackgroundModular 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 nonmechanical complications? (3) What are the implant failure rates at 5, 10, and 15 years? (4) How often is limb salvage achieved using this prosthesis?MethodsBetween 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 followup, leaving 110 reconstructions in 101 patients for review. The reverse Kaplan-Meier method was used to calculate median followup, which was equal to 8.9 years (95% confidence 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.ResultsComplications 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 difference in loosening between revision (five of 17 [29%]) and primary reconstructions (eight of 61 [13%]) (hazard ratio [HR], 1.72; 95% CI, 0.55–5.38; p = 0.354). Hydroxyapatite-coated uncemented implants had a lower risk of loosening (two of 42 [5%]) than uncoated uncemented implants (11 of 36 [31%]) (HR, 0.23; 95% CI, 0.05–1.06; p = 0.060). Structural complications occurred in 15 reconstructions (15 of 110 [14%]). Infections occurred in 14 reconstructions (14 of 110 [13%]). Ten patients had a local recurrence (10 of 101 [10%]). With failure for mechanical reasons as the endpoint, the cumulative incidences of implant failure at 5, 10, and 15 years were 16.9% (95% CI, 9.6–24.2), 20.7% (95% CI, 12.5–28.8%), and 37.9% (95% CI, 16.1–59.7), respectively. We were able to salvage some of the f...

CORR Insights®: What Are the Long-term Results of MUTARS® Modular Endoprostheses for Reconstruction of Tumor Resection of the Distal Femur and Proximal Tibia?

“…The data provided by Bus et al [3] indicates that the MUTARS 1 system appears comparable to other systems in terms of implant survival. Owing to heterogeneity among tumor patients in terms of tumor biology, demographic parameters or extent of the defect, there is a need for large series with standardized description of the these parameters.…”

“…The study by Bus et al [3] focuses on both the complication and long-term performance of the modular MUTARS 1 prosthetic implant design. The study also describes the applicability and reliability of this implant design.…”

Structural Failure of a Modern Knee Tumor Megaendoprosthesis

“…Structural failures were observed in 7% of the cases including prosthesis breakage, periprosthetic fractures, and articular hinge or polyethylene liner failures. Bus et al reported a 14% structural failure rate of MUTARS® knee prostheses after a mean of three years, consisting of fractures and unlocking of the locking mechanism, instances of wear, fractures of the femoral component, and stem fractures [6]. Ilyas et al reported about one femoral stem fracture of a HMRS prosthesis three years after surgery [9].…”

Biological Reconstruction in Bone Sarcomas: Lessons from Three Decades of Experience

“…Patients should be alerted to this possibility so that if they do have any bacterial infection they can receive suitable treatment in a timely manner, thus avoiding contamination of the allograft. With learning such measures through experience, we have been able to reduce the number of complications. Another consideration regarding infection is sterility of the allograft.…”