Correlation of prosthetic femoral head size and/or design with longevity of total hip arthroplasty.

Sixty-seven Mueller and 84 Charnley total hip arthroplasties were followed up for a minimum of seven years; pain, radiographic radiolucency, and prosthetic component loosening were evaluated. The patients who had Mueller total hip prostheses had significantly more pain at five (p less than 0.021) and seven years (p less than 0.001). No statistical differences were found between the two prosthetic groups in regard to incomplete or complete radiolucency or loosening of the femoral component, or incomplete or complete nonprogressive radiolucency of the acetabular component. The Mueller acetabular cup was loose in 15%, as compared with 4% for the Charnley group (p less than 0.032). A survival analysis at five and seven years revealed that the success rate for Charnley total hip arthroplasties was 94% and 86%, respectively, as compared with 87% and 70%, respectively, for Mueller total hip arthroplasties (p less than 0.003). This difference possibly is due to the large Mueller femoral head; if so, resurfaced hips would also experience earlier acetabular loosening.