Muscle function after femoral shortening osteotomies at the subtrochanteric and mid-diaphyseal level. A follow-up study.

Relative femoral shortening length at the subtrochanteric (ST) and mid-diaphyseal (MD) level was compared with isokinetic muscle strength more than 2 years postoperatively. For the ST level no upper limit for shortening length could be detected. For MD osteotomies the relative shortening length was negatively correlated to muscle strength. There was a significant difference at the MD level between those shortened more or less than 10%, indicating an upper limit of 10% of the femoral length for regaining normal muscle strength. For correction of leg length inequality and for shortening of unaccepted tallness, these results should be taken into account when choosing the level for osteotomy.