Lessons of 30 years of total hip arthroplasty.

The following are lessons of 30 years of total hip arthroplasty (THA): Prosthetic components should allow for easy preoperative graphic planning with one or two templates only. Polyethylene is the weak link in THA and ought to be replaced by perfectly concentric metallic sockets and femoral heads of casted Cr/Co/Mo alloys. The operating technique should guarantee large exposure, suitable orientation of both components, and adequate fixation. Loosening is correlated with loss of bone stock and changes of the position of the implants. In case of progressive bone loss, one should reoperate already in presence of slight clinical symptoms to prevent more difficult and dangerous revisions. To evaluate objectively the outcome of THA, a combined data and roentgenographic documentation system with standardized terms and scales is necessary.