Survivorship analysis of 141 modular metallic endoprostheses at early followup

Although our institution historically has been known for its use of osteoarticular allografts in limb salvage surgery for tumors, during the last 8 years there has been an increase in the use of metallic modular endoprostheses. A retrospective review of 141 patients in whom a modular endoprosthesis was implanted in the past 8 years was done, and survival data were compiled using Kaplan-Meier survival analysis, clinical score was determined using a previously described system, and a multivariate regression analysis was done to identify independent risk factors. There were 13 failures (defined as need for revision of the majority of the prosthetic components, excluding cases of local recurrence) yielding an overall implant survival of 91%. Based on Kaplan-Meier estimates, the endoprosthetic survival rate was 88% at 3 years and 76% at 5 years; per location, it was 100% for the proximal humerus, 100% for the proximal femur, 87% for modular knees, and 53% for total femoral implants at 3 years. The clinical scores were good to excellent in 74% of the patients. Multivariate analysis showed that only location and infection were independent risk factors for prosthesis failure. Loosening, infection, and dislocation were independently predictive of a fair or poor clinical score. Age, gender, diagnosis, length of implant, dislocation, nor failed prior allograft had an independent effect on implant survival or clinical outcome. The proximal humeral and proximal femoral implants had greater survival rates than modular knee and total femoral implants. Conversion of failed allografts to modular endoprostheses had a trend for a higher failure rate, but after a multivariate analysis, did not prove to be an independent risk factor for failure. We think that our experience is similar to other endoprosthesis survivorship reports in the literature with short-term followup.