Rotational-guided growth

Abstract

Background: Rotational deformities of the femur and tibia are some of the most common orthopedic alignment problems in the lower extremity. In-toeing and out-toeing are common complaints seen by pediatric orthopedic surgeons as well. The idea of guided growth to correct axial rotation deformities in children is appealing. The purpose of this study was to investigate this concept and to test it in a large animal model taking advantage of the human like dimensions and biomechanics. Method: To generate axial-rotational growth we tether the growth plate on both sides at a fixed inclined angle on each side a cable with two screws. This construct was called the Percutaneous Progressive Derotator (PPD). Eight calves, two-month old, four male (50%) and the other four female, were used as models. The PPD device was implanted at the distal physis of the right metacarpal in an external rotation configuration, leaving the left side as control. The PPD device was left in for 3 months and was then removed. The total followed up was 2 years and 3 months. Results: The hypothesis that guided growth was possible in large animals has been confirmed. Rotation of 24° average were achieved in the right metacarpus of the growing cattle (P < 0.001), using the torque generated in the growth plate by the PPD.