Postoperative rotational instability after tibial plateau-leveling osteotomy is associated with acute cranial cruciate ligament rupture and meniscal injury.

OBJECTIVE: To determine the prevalence and associated risk factors of postoperative rotational instability following tibial plateau-leveling osteotomy (TPLO) in dogs with cranial cruciate ligament (CrCL) rupture. METHODS: A retrospective analysis of medical records was performed for dogs undergoing TPLO for CrCL rupture at a single referral institution from 2018 through 2025. Rotational instability was defined as persistence of a positive tibial pivot test (TPT) after TPLO requiring placement of an antirotational suture. Signalment, clinical findings, radiographic variables, and intraoperative data were compared between rotationally unstable and stable stifles. Variables associated with instability in univariable analysis were included in a multivariable logistic regression model. RESULTS: A total of 312 stifles met inclusion criteria. Postoperative rotational instability was identified in 77 of 312 stifles (24.6%). In multivariable analysis, chronic presentation was associated with lower odds of instability (OR, 0.41; 95% CI, 0.20 to 0.85). Increasing lameness severity (OR, 1.54/grade increase; 95% CI, 1.07 to 2.24), complete CrCL rupture (OR, 23.48; 95% CI, 6.50 to 152.25), and meniscal tear (OR, 2.68; 95% CI, 1.26 to 5.88) were associated with higher odds of instability. Age, body weight, osteoarthritis score, and preoperative tibial plateau angle were not independently associated with instability after adjustment. CONCLUSIONS: Rotational instability following TPLO is relatively common and is primarily associated with lesion severity and acute presentation. CLINICAL RELEVANCE: Recognition of these risk factors may prompt more careful intraoperative assessment for rotational instability using the tibial compression pivot test, thereby helping identify dogs that may benefit from adjunctive antirotational stabilization.