We assessed the medium-term outcome of three methods of isolated calf lengthening in cerebral palsy by clinical examination, observational gait analysis and, where appropriate, instrumented gait analysis. The procedures used were percutaneous lengthening of tendo Achillis, open Z-lengthening of tendo Achillis and lengthening of the gastrosoleus aponeurosis (Baker’s procedure).

We reviewed 195 procedures in 134 children; 45 had hemiplegia, 65 diplegia and 24 quadriplegia. We established the incidence of calcaneus and recurrent equinus and identified ‘at-risk’ groups for each. At follow-up, 42% had satisfactory calf length, 22% had recurrent equinus and 36% calcaneus. The incidence of calcaneus in girls at follow-up was significantly higher (p = 0.002) while boys had an increased rate of recurrent equinus (p = 0.012).

Children with diplegia who had surgery when aged eight years or younger had a 44% risk of calcaneus, while those over eight years had a 19% risk (p = 0.046). Percutaneous lengthening of tendo Achillis in diplegia was the least predictable, only 38% having a satisfactory outcome compared with 50% in the other procedures.

The incidence of recurrent equinus in hemiplegic patients was 38%. Only 4% developed calcaneus. The type of surgery did not influence the outcome in patients with hemiplegia or quadriplegia.

Severity of involvement, female gender, age at operation of less than eight years and percutaneous lengthening of tendo Achillis were ‘risk factors’ for calcaneus. Hemiplegia, male gender, and an aponeurosis muscle lengthening increased the risk of recurrent equinus.