Aims: determine risk factors associated with component loosening so that measures can be implemented to improve component durability. Methods: The þrst 300 patients with Wright Medical Conserve Plusª metal-on-metal hip resurfacings were analyzed radiographically for radiolucencies and failed components were analyzed histologically after the components were sectioned. The group average age was 48 years, 75% were male, and most were operated for OA. At an average of 3 years, 7 hips required revision for femoral loosening, none for acetabular loosening. These included 4 of the þrst 100 cases, 1 in the 2nd 100, 2 in the 3rd 100. Radiographic lucencies were found in 9 of the 1st 100, and 3 in each of the of the 2nd and third 100. Results: The etiology of femoral loosening was found to be multifac-torial and risk factors included: substandard bone preparation, presence of large cysts or bone defects, cement technique, and patient activity.

The short metaphyseal stem serves as a useful Ç barometer È for þxation and impending loosening. Conclusions: Femoral loosening can be minimized by better patient selection and by excellent bone preparation and cement technique. Patients with compromised bone stock may still be successfully resurfaced if the extent of the defects is not excessive and/or the stem is cemented in.

Aims: Examine the short term failures of the Wright Medical Conserve Plusª metal-on-metal hip resurfacing to determine risk factors, so that measures could be implemented to prevent future failures. Methods: Two hundred and ninety six Conserve Plus hip resurfacings were performed in an FDA IDE multi-center trial. 9 femoral neck fractures occurred in 3 of the 9 centers. The time to failure ranged from less than 1 week to 21 weeks. The revised resurfaced heads were sectioned and examined by micro-radiography and histology, along with pre and post-operative radiographs and clinical histories that were discussed with the surgeons. Results: Several risk factors were identiþed including poor bone quality large or multiple cysts in the femoral head or neck, leaving reamed bone uncovered, improper implant placement and incorrect patient selection. Lessons learned from this analysis resulted in no further neck fractures to date in 369 additional Conserve Plus components that have now been implanted. Conclusions: Osteoarthritic femoral necks rarely fracture and neck fracture in resurfaced femoral heads can be largely prevented by better patient selection, improved surgical technique to prevent neck notching and better implant placement.