Femorotibial kinematics in dogs treated with tibial plateau leveling osteotomy for cranial cruciate ligament insufficiency: An in vivo fluoroscopic analysis during walking

Objective To determine the ability of tibial plateau leveling osteotomy (TPLO) to address abnormal femorotibial kinematics caused by cranial cruciate ligament (CCL) rupture during walking in dogs. Study design Prospective, clinical. Animals Sixteen dogs (20-40 kg) with unilateral complete CCL rupture. Methods Lateral view fluoroscopy was performed during treadmill walking preoperatively and 6 months after TPLO. Digital three-dimensional (3D) models of the femora and tibiae were created from computed tomographic (CT) images. Gait cycles were analyzed by using a 3D-to-2D image registration process. Craniocaudal translation, internal/external rotation, and flexion/extension of the femorotibial joint were compared between preoperative and 6-month postoperative time points for the affected stifle and 6-month postoperative unaffected contralateral (control) stifles. Results In the overall population, CCL rupture resulted in 10 +/- 2.2 mm (mean +/- SD) cranial tibial translation at midstance phase, which was converted to 2.1 +/- 4.3 mm caudal tibial translation after TPLO. However, five of 16 TPLO-treated stifles had 4.1 +/- 0.3 mm of cranial tibial subluxation during mid-to-late stance phase, whereas 10 of 16 TPLO-treated stifles had 4.3 +/- 0.4 mm of caudal tibial subluxation throughout the gait cycle. Overall, postoperative axial rotational and flexion/extension patterns were not different from control, but stifles with caudal tibial subluxation had more external tibial rotation during mid-to-late stance phase compared with stifles with cranial tibial subluxation. Conclusion TPLO mitigated abnormal femorotibial kinematics but did not restore kinematics to control values in 15 of 16 dogs during walking. Clinical significance Tibial plateau leveling osteotomy reduces cranial tibial subluxation during walking, but persistent instability is common.