Reduction of Excessive Tibial Plateau Angle Using a Hinged Fixator and Distraction Osteogenesis

Introduction: A 24-week-old, spayed female, Rhodesian Ridgeback was referred for premature eccentric closure of the caudal aspect of the proximal tibial physis resulting in an excessive tibial plateau angle (TPA) after sustaining comminuted diaphyseal fractures of the left femur, tibia, and fibula.

Materials and Methods: Surgery was performed to reduce the TPA of 50° using a hinged circular external fixator (IMEX Veterinary, Inc., Longview, TX) and institute distraction osteogenesis for limb lengthening.

Results: Distraction was initiated the day following surgery at a rate of ~1 mm per day as measured along the caudal cortex of the tibia with a rhythm of three distractions daily. At 19 days, postoperatively, there was 17 mm of distraction along the caudal cortex. 7 weeks following surgery, the dog sustained a fracture of the osteopenic tuber calcaneus which was stabilized with orthogonal plates. 12 months after surgery, the dog had a mild weight-bearing lameness at a trot with the limb held in slight abduction and external rotation at rest. Radiographs revealed mild valgus, recurvatum of the left tibial diaphysis, and a TPA of 3°.

Discussion/Conclusion: The magnitude of the crural deformity, excessive TPA, and limb length discrepancy did not offer a favorable outcome for a companion animal. The hinged circular fixator allowed for improvement of lameness, restoration of an acceptable TPA, resultant limb lengthening, and partial correction of angular deformity in this dog.

Acknowledgment: There was no proprietary interest or funding provided for this project.