Muscular strength after callotasis limb lengthening.

Seven patients (average age, 9.2 years; range, 7.6-10.6 years) underwent collotasis lengthening of a congenital short femur. The isometric voluntary contraction strength of the knee extensor muscles was measured for each leg immediately before and at 6-month intervals for 2 years, starting from 2 months after the fixator was removed. The normal side was always stronger, even when strength was standardized for an anthropometric estimate of the thigh muscle and bone cross-sectional areas. The increase in strength was correlated with the increase in limb size, both in the normal and in the lengthened limb. Although leg length discrepancy was equalized by the end of the procedure, the functional characteristics of the lengthened limb remained impaired for a significant time.