Comparison of Tibial Plateau Angle Changes after Tibial Plateau Leveling Osteotomy Fixation with Conventional or Locking Screw Technology

Objective To compare the effects of locking and conventional screws on postoperative tibial plateau angle (TPA), osteotomy healing, and complication rate after tibial plateau leveling osteotomy (TPLO) in dogs treated for naturally occurring cranial cruciate ligament (CCL) rupture. Study Design Prospective clinical study. Study Population Dogs (n=118) with CCL rupture. Methods Dogs (>= 20 kg) with unilateral CCL rupture and sufficient bone stock for TPLO and use of a 3.5-mm-broad or -narrow TPLO plate were sequentially allocated to have plate fixation with locking or conventional screws. Data analyzed included breed, age, sex, body weight, body condition score, limb operated, implants used, meniscal status, operative time, and days to recheck. Preoperative, immediate postoperative, and 8-week recheck mediolateral radiographs were reviewed, and TPA, complications, and healing status were evaluated. Results Stifles in the locking screw group had significantly less change in postoperative TPA than stifles in the conventional screw group. Locking screw fixation also had significantly higher grades of osteotomy healing, assessed on a mediolateral radiographic view. Conclusions TPLO plates secured with locking screws are acceptable when compared with those secured with conventional screws; osteotomy healing is improved and TPA better conserved when using locking screws. Clinical Relevance Locking screw fixation serves to increase stabilization of TPA during TPLO healing and provides improved radiographic evidence of osteotomy healing.