Spontaneous recovery of experimental valgus deformity in lambs

Introduction: Angular deformity in the growing skeleton of animals, especially in the radius and ulna, is occasionally seen in clinical practice. The mechanism of spontaneous correction of these angular deformities however remains to be elucidated. The purpose of our experiment was to explore the ability of a growth plate to correct an induced valgus deformity, and to study the mechanism of correction. Methods: Before beginning the study, valgus deformity of the distal radius had been induced in lambs by the application of a device that causes asymmetrical compression of the growth plate. The study began after removal of the device and spontaneous correction of the induced deformity was observed weekly for 20 weeks. The angles of the deformity and longitudinal growth on the medial and lateral portions of the growth plate were respectively measured on craniocaudal and mediolateral radiographs. Results and conclusions: Spontaneous correction of the valgus deformity occurred during the first 16 weeks. It resulted from asymmetrical growth characterised by restricted activity of the medial portion of the growth plate (14.8%) in comparison to the lateral portion of the experimental radius, and also in comparison to the medial portion of the control radius.