Muscular function and bone mass after knee arthroplasty.

We report a study of 28 women with severe primary gonarthrosis followed for 1 year. Variations in bone mineral density and in functional behaviour of knee extensors and flexors were studied before and after implantation of uncemented total knee prosthesis. A functional deficit was noted in the extensor apparatus, which increased in the first 6 months following surgery. This strength was not improved 1 year following the arthroplasty, but it was more efficient as shown by the reduction of muscle fatigue. Flexor strength was conserved and a pathological muscle balance was maintained, reaching maximum efficiency over a smaller joint range.