The subtalar extra-articular arthrodeses performed at the Texas Scottish Rite Hospital for Crippled Children in Dallas during the five-year period from 1955 through 1959 were reviewed. Of the 112 procedures done on paralytic valgus feet, forty-two feet (37.5 per cent) were judged to have unsatisfactory results.

The chief complication was late varus deformity, which required one or more subsequent surgical procedures for correction. This complication has, to our knowledge, not been emphasized in any of the previously reported series.

The cause of this complication was not the bone-block procedure itself but the combination of subtalar extra-articular arthrodesis with the simultaneous transposition of both peroneal muscles. This combination causes muscle imbalance with excessive inversion power which leads to progressive, severe, disabling, late varus deformity resistant to subsequent surgical correction.

Therefore, we should like to emphasize that, certainly in younger children, both peroneal tendons should not be transplanted at the time of the subtalar extra-articular arthrodesis for paralytic valgus feet regardless of the existing inversion-eversion imbalance.

Function of the peroneus longus should be retained to preserve active pronation and abduction of the fore part of the foot after the hind part has been stabilized by the arthrodesis.