Growth disturbance following metaphyseal bending fractures of the proximal tibia--an experimental study in the mini pig.

Based on our clinical experience, we postulate that the unilateral "posttraumatic genu valgum" develops on the grounds of an unreduced primary valgus deformity. This induces a disturbance of the consolidation on the medial aspect of the fracture. Subsequently, a partial medial stimulation of the epiphyseal plate develops resulting in a secondary valgus deformity. We succeeded in proving experimentally this postulate using the Mini Pig as an experimental model. We investigated 33 tibiae of 17 Mini Pigs. With radiological follow-up studies we were able to show that the operatively created primary valgus deformity induces an increased valgus deformity of functional significance. This is a model of the unreduced fracture in men. However, the transection of the pes anserinus and the periost per se did not provoke a significant valgus formation. Based on these experimental results and our clinical findings we postulate the following treatment for the metaphyseal bending fractures of the proximal tibia in men: 1. Accurate, usually conservative, reduction of any primary valgus malposition of the fracture. 2. Retention of the corrected position of the tibia in a plaster cast. 3. Compression of the medial aspect of the fracture to prevent disturbance of consolidation and subsequent development of valgus deformity.