Loss of knee range of motion in leg lengthening.

STUDY DESIGN: Prospective longitudinal study. OBJECTIVE: To determine factors predictive of loss of movement in a cohort of patients undergoing femoral lengthening. BACKGROUND: Loss of joint movement due to poor adaptation of the muscle is a major problem during limb lengthening but remains poorly documented in the literature. METHODS AND MATERIALS: A validated technique using a modified goniometer was used to measure knee motion. Measurements were taken before surgery, prelengthening, during lengthening, and at 6 and 12 months post frame removal. The subjects were 35 patients with a mean age of 22 years (+/-12.8 years), 23 men and 12 women, undergoing femoral lengthening by the Ilizarov method. RESULTS: The pattern of recovery of knee range of movement that was observed showed that 88% of knee flexion was regained by 6 months, 92% of patients regained their knee flexion by 12 months, and 97% by 18 months. Significant loss of knee flexion occurred in the latent period prior to lengthening, mean loss 79 degrees (+/-22.8 degrees). All patients regained full knee extension by the end of lengthening, but 2 patients who had fixed flexion deformities of > 40 degrees developed posterior subluxation of the knee. CONCLUSIONS: The unexpected loss of movement observed in the prelengthening period indicates that physical therapy efforts must be directed to this phase in order to accelerate the recovery of joint range and reduce the muscle-related complications that can occur during limb lengthening.