Can persistent drop foot after calf muscle lengthening be predicted preoperatively?

UNLABELLED: Calf muscle lengthening usually corrects equinus gait satisfactorily in stance. While in swing, the foot remains in drop foot in approximately half the limbs. The aim of this study was to evaluate if any preoperative clinical findings or kinematic and kinetic data could predict the outcome regarding drop foot. The study included 34 children with cerebral palsy. The average age was 9.3 years. Only children with preoperative maximum ankle dorsiflexion in stance and maximum ankle dorsiflexion in swing more than 2 standard deviations below the normal mean were included. The children underwent preoperative and postoperative clinical examination and gait analysis. Forty calf muscle lengthenings were performed (26 tendo-achilles lengthenings, 14 gastrocnemius recessions). Nineteen of 40 limbs remained in drop foot despite satisfactory correction in stance. There was a significant association between postoperative drop foot and increased preoperative maximum plantar flexion in initial swing (P = .004; odds ratio, 0.906). A limited number of tests of preoperative selective motor control of dorsiflexion of the ankle indicated that normal function is strongly indicative of postoperative normal swing phase. There were no significant associations between postoperative drop foot and preoperative clinical findings, gait function, type of gait pattern, type of cerebral palsy, and type of operation. Preoperative maximum plantar flexion in an initial swing of less than -42 degrees and a preoperative normal selective motor control of dorsiflexion of the ankle are strongly indicative of postoperative normal swing phase. A lower selective motor control score rather than normal function is not predictive of either normal swing or drop foot. LEVEL OF EVIDENCE: 2.