A large collar increases neck resorption in total hip replacement:204 hips evaluated during 5 years

We evaluated the effect of a prosthetic collar on the proximal femoral bone in 204 hips without any signs of loosening after 5 years. The patients were operated on at 5 centers, using different prosthetic designs, but the same cementing technique. Resorption was more often found in cases with a true and large collar (Lubinus, HD2, Scanhip) than in cases with a flanged or tapered stem (Charnley, Exeter). The resorption was also more pronounced with the former designs. It was concluded that, in spite of theoretical advantages, a large collar is not only unnecessary but may also have negative long-term effects.