Validation of a genu valgum model in a rabbit hind limb.

Numerous techniques exist to correct pediatric angular deformity by asymmetrically inhibiting physeal growth. Despite decades of surgical experience, little is known about the determinants of success or failure of temporary hemiepiphysiodesis. We lack a basic understanding of tolerances and kinematics of the surgically restrained physis. Furthermore, little is known about the influence of implant design and placement on efficacy of deformity correction and rebound growth. We have undertaken a pilot research study with the goal of producing genu valgum in New Zealand white rabbits. This report comprises our initial experience and observations in performing hemiepiphysiodesis with staples and 2-hole plate techniques. The experimental hypotheses proposed by this article are as follows: (1) a staple or plate applied to the proximal lateral tibial physis of a rabbit hind limb will reliably create a valgus deformity of the knee; (2) the plate or staple will create this deformity without permanently damaging the proximal tibial physis; and (3) provided the implant remains in situ, there will be no difference between the plate and staple constructs with respect to the magnitude or rate of deformity produced. Further studies will aim to use this model to investigate technical issues related to physeal instrumentation.