Abstract
Introduction
The current investigation includes a retrospective review of the experience of five Institutions with distal femur megaprostheses for tumor over a twenty year period, to analyze the incidence and etiology of failure, using a new classification system based upon the failure modes.
Methods
Between 1974 and 2008, 2174 patients underwent primary limb preservation for a benign or malignant extremity tumor using a metallic megaprosthesis at five Institutions, 951 (43.7%) were distal femur replacements. Retrospective analysis of complications according to the Letson and Ruggieri Classification was performed and Kaplan-Meier curves of implant survival were defined.
Segmental megaprosthetic reconstruction failures were categorized as mechanical and non-mechanical failures.
Results
A total of 951 skeletally mature patients received a segmental endoprosthesis for the treatment of an oncologic condition. Overall 261 (27%) of the primary procedures were considered failures. There were 137 mechanical failures (14.4%): 12 (1.3%) Type 1 (soft tissue failure), 65 (6.8%) Type 2 (aseptic loosening), and 60 (6.3%) Type 3 (structural failure). Non-mechanical causes accounted for 124 failures (13%): 45 (4.7%)Type 4 (tumor progression) and 79 (8.3%) Type 5 (infection). The overall implant survival to all modes of failure was 77% at 10 years and 73% at 20 years. The implant survival to aseptic loosening was over 90% at 10 years.
Conclusion
Most frequent cause of failure was infection followed by aseptic loosening and structural failure. The implant survival at long term was quite satisfactory.
