5-10-year results with the straight-shaft Müller prosthesis

Abstract

103 patients with 106 Müller straight stem prostheses could be evaluated clinically and radiologically after an average follow-up period of 6.8 years (range 5 to 10 ys.). Although until now no revision for aseptic loosening has become necessary 3 p.c. of the stems and 11 p.c. of the acetabular components showed radiological loosening. The clinical results were rated as satisfactory. After surgery 67 p.c. of the patients were completely painfree, 28 p.c. still had slight pain, 4 p.c. moderate and 1 p.c. severe pain. The investigation concentrated particularly on radiographic changes of the interface of the femur. Whereas radiolucency typically was non-progressive and located in the proximal part of the femur we found an increasing atrophy of the cortical bone on the calcar. Moreover, we found a continuous and increasing subsidence of the stem during the whole period of observation. At the time of follow up 56 p.c. of the straight stems had subsided about 2 mm and more. Calcar atrophy and radiolucency were significantly less present in femurs with a tapered medullary canal than in those with a cylindrical shape.