Risk factors for tibial tuberosity fracture after tibial plateau leveling osteotomy in dogs

Objective-To evaluate factors that predispose to tibial tuberosity (TT) fracture after tibial plateau leveling osteotomy (TPLO) in dogs. Study Design-Retrospective study. Animals-Dogs (n = 182) with cranial cruciate ligament (CCL) rupture undergoing 213 TPLO surgeries. Methods-Medical records and radiographs of 2 groups of dogs that had TPLO surgery (2000-2001, 2004-2005) were evaluated to determine the effect of operative technique and surgeon experience on TT fracture. Results-TT fracture was diagnosed in 8 dogs (9 TPLO, 4.2% of surgical procedures). Four fractures occurred after unilateral TPLO in 167 dogs (2.4%), 4 fractures occurred after simultaneous bilateral TPLO in 5 dogs (40%), and 1 fracture occurred after staged bilateral TPLO in 36 dogs (2.8%). Simultaneous bilateral TPLO resulted in a 12.4 times higher odds of TT fracture versus unilateral TPLO (P = .046). The mean absolute thickness of the TT after TPLO was less in dogs sustaining TT fractures (7.2 +/- 2.2 mm) than those that did not (10.8 +/- 2.7 mm, P < .0001). The odds of fracture decreased by 37% when the absolute TT width postosteotomy increased by 1 mm (P < .0001). An increase in tibial plateau angle at follow-up versus immediately postoperative was associated with TT fracture (P = .025). Surgeon experience was not associated with TT fracture. Conclusion-A combination of surgical decision-making and surgical technique play a role in the occurrence of TT fracture after TPLO. Simultaneous bilateral TPLO was associated with a high percentage of TT fracture. Clinical Relevance-Careful planning of osteotomy positioning is advised while performing TPLO surgery. (C) Copyright 2008 by The American College of Veterinary Surgeons.