Orthogonal Evaluation of Changes in Tibial Plateau Angles After Tibial Plateau Leveling Osteotomy in The Cranial Cruciate Ligament Defitient Stifle of Dogs. A Ten-Year Review.

VECCHIO NE; VECCHIO LE; HOSGOOD G; TOBIAS T

Bologna

Congreso; World Veterinary Orthopaedic Congress; 2010

World Veterinary Orthopaedic Society

Introduction Cranial cruciate ligament (CCL) rupture in dogs is a common orthopedic condition. Several procedures were described for stifle reconstruction. Techniques may be divided into intracapsular, extracapsular, and techniques aimed at changing the geometry and biomechanics of the stifle regardless of the integrity of the CCL. Tibial plateau leveling osteotomy (TPLO) utilizes a curved osteotomy around the tibial plateau with realignment of tibial plateau at a smaller angle relative to the long axis of the tibia. The tibial plateau angle (TPA) measured from both pre- and post-operative radiographs, as described by Slocum1, is used by the surgeon to calculate the amount of rotation needed and to evaluate the angular reduction respectively2. Leveling the tibial plateau neutralizes cranial tibial thrust during the stance fase of normal gait 3. For neutralization to take place, the TPA should be reduced to 5 to 6.5o. A more recent report showed that TPAs up to 14o allow clinical results comparable to those achieved with TPA in the 5 to 6.5 o range4. We reviewed our ten-year experience with the TPLO procedure recording postoperative changes in the TPA in orthogonal radiographic views. Host factors, implant characteristics and TPLO technique features were also recorded. Materials & methods Medical records from January 1st 1999 to December 31st 2008 were reviewed. Information recorded included the dog?s age, sex, breed, and body weight, the pre-, postoperative and recheck TPA measured in medio-lateral (mTPA) and caudo-cranial (cTPA) radiographs, time of recheck, tibial tuberosity pin placement (placed through the tibial tuberosity at the insertion of the patellar tendon and across the osteotomy), type of implants used, diameter of the osteotomy blade, and use (yes/no) of the alignment jig during surgery. All radiographs met the standards described for measurement of the TPA1 and all TPAs were measured by the same author. All numerical data was summarized as mean and SD and quartiles. All categorical data was summarized as frequencies and proportions. Each stifle was assumed an independent event. For the purpose of statistical analysis, the differences in the mTPA from post mTPA - pre mTPA and from recheck mTPA - post mTPA were calculated. The differences in the cTPA were calculated similarly. The effect of plate type, screw size, sex, weight, age (years), jig use (y/n), cranial pin use (y/n) were explored for an effect on mTPA difference and cTPA difference using regression analysis. Age was rounded down to the nearest year. Weight was categorized in 10 kg increments. Stepwise selection was used with the effect variables included at p