High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years followup.

Background: Currently, the two most commonly used options for the revision of femoral components in North America are: cylindrical, nonmodular, cobalt-chromium stems and tapered, fluted, modular, titanium (TFMT) stems. Previous reports have cited high failure rates with cylindrical cobalt chrome stems in large femoral defects but the longer term survival of the fluted stems is unknown.

Questions/purposes: We examined the 5- to 10-year survival of TFMT stems implanted for severe femoral defects.

Methods: We reviewed all 65 patients with severe proximal bone defects revised with the TMFT stem between January 2000 and 2006. Ten were lost to followup and seven were dead, leaving 48 patients for followup at 5 to 10 years (mean, 84 months; range, 60-120 months). All patients completed five quality-of-life (QOL) questionnaires. Radiographs were evaluated for loosening, subsidence, and preservation of proximal host bone stock.

Results: Implant survivorship was 90%. No patient underwent revision for either subsidence or loosening. Subsidence occurred in seven patients (average, 12.3 mm) but all achieved secondary stability. Five patients underwent revision as a result of fracture of the stem and all had the original standard stem design, which has since been modified. All five implant fractures occurred at the modular stem junction. Mean QOL outcomes were: WOMAC = 81 (pain), Oxford = 75, SF-12 = 54 (mental) and 38 (physical), UCLA Activity = 4, and satisfaction overall = 73.

Conclusions: Midterm survivorship of modular titanium stems in large femoral defects is high; however, ongoing surveillance of stem junctional fatigue life is required.

Level Of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.