LONG-TERM BONE REMODELING AROUND THE CHARNLEY FEMORAL PROSTHESES

Femoral bone remodeling after total hip replacement was studied by fol lowing patients who received 326 Charnley femoral prostheses for 10 to 20 years (mean, 13.3 years), The radiographic state of bone remodelin g was visually assessed and measured with a digitizer, Demineralizatio n that started proximally and then progressed distally caused cortical thinning, ,which correlated with widening of the intramedullary canal , not with changes that developed in the periosteal width, and occurre d in the medial femoral neck, around the proximal half of the stem, an d around the distal half in 87%, 33%, and 10%, respectively, Cortical thinning around the distal half of the stem was always accompanied by proximal thinning, and extensive cortical thinning (both proximal and distal) correlated with both lower clinical scores and radiologic loos ening of the femoral prosthesis, A low canal flare index of Noble, a l arge canal width, and a patient age of 60 years or more were risk fact ors for extensive cortical thinning, Accelerated polyethylene wear was related to resorption of the medial femoral neck but not to cortical thinning or radiological loosening, Cortical thickening occurred only around the distal half of the stem in 29%, These findings establish a basis for the performance of cemented femoral prostheses, and allow co mparison of bone remodeling when evaluating other femoral prostheses.