RM isoelastic total hip arthroplasty. A review of 34 cases

Thirty-four cases of RM isoelastic total hip arthroplasty were followed for an average period of 42 months after surgery. Eleven (32%) were revised because of purely mechanical loosening of the femoral stem. Of the remaining cases, 16 (69%) had poor Mayo hip scores and only 2 (9%) had good results. Radiologic evidence of loosening of the uncemented femoral stem, as exemplified by radiopaque lines within radiolucent zones, the so-called "pedestal sign" of increased density at the stem tip, and proximal bony overgrowth around the collar were present in all 11 cases that were revised. Marked stem shift and localized cortical hypertrophy were noted in nine revised cases. Radiopaque lines were observed in 11 nonrevised cases, all with poor Mayo hip scores.