We performed CT to investigate how treatment may modify the basic skeletal pathology of congenital club foot. Two homogenous groups of patients treated by one of the authors (EI) or under his supervision were studied. The first included 32 patients with 47 club feet reviewed at a mean age of 25 years and treated by manipulation, application of toe-to-groin plaster casts and an extensive posteromedial release. The second included 32 patients with 49 club feet reviewed at a mean age of 19 years and treated by the Ponseti manipulation technique, application of toe-to-groin plaster casts and a limited posterior release.

At follow-up the shape of the subtalar, talonavicular and calcaneocuboid joints was found to be altered in many feet in both groups. This did not appear to be influenced significantly by the type of treatment performed. Correction of the heel varus and the increased declination angle of the neck of the talus was better in the club feet of the second group, whereas reduction of the medial subluxation of the navicular was better in the first. There was a marked increase in the external ankle torsion angle in the first group and a moderate increase of this angle in the second group, in which medial subluxation of the cuboid on the anterior apophysis of the calcaneum was always corrected. Equinus was corrected in both groups but three-dimensional CT reconstruction of the whole foot showed that cavus, supination and adduction deformities were corrected much better in the second group.

We reviewed the radiographs of 49 patients with Perthes' disease at the stage of fragmentation and also after the end of skeletal growth to assess the value of the lateral pillar classification of Herring. The average age of the patients at diagnosis was 7 years 6 months and the mean follow-up was 24 years. Ten of the 11 Herring group-A hips showed good reconstruction of the femoral head. There were good results in group-B hips when the patients were less than nine years of age at diagnosis. All 11 group-C patients showed hip deformity at follow-up. The Herring classification provides a valid long-term prognosis in Perthes' disease, although age at diagnosis is also an important prognostic factor. The classification is relatively easy to apply, is reliable, and requires only an anteroposterior radiograph taken during the fragmentation stage of the disease.