Effect of the Centre of Rotation in Tibial Plateau Levelling Osteotomy on Quadriceps Tensile Force: An Ex Vivo Study in Canine Cadavers.

Objective The aim of this study was to determine the effect of the centre of rotation in tibial plateau levelling osteotomy (TPLO) on the tensile force of the quadriceps. Materials and Methods Tibial plateau levelling osteotomy was performed on the left pelvic limbs from 20 normal adult Beagle cadavers. To replicate the tensile force of the quadriceps, gastrocnemius and stifle flexor muscles, these muscles were replaced with wires. The tensile force of each wire, cranial tibial displacement and internal tibial rotation were measured under the following conditions: intact cranial cruciate ligament, transected cranial cruciate ligament, ideally centred osteotomy TPLO (ICO group) and distally centred osteotomy TPLO (DCO group). The ratios of the tensile forces for the wires divided by the vertical force were used for analyses. Results The mean intact and post-TPLO tibial plateau angles (TPA) in the ICO group were 30.3 degrees +/- 1.9 degrees and 6.1 degrees +/- 1.6 degrees, respectively, and those in the DCO group were 29.8 degrees +/- 2.4 degrees and 6.8 degrees +/- 0.9 degrees, respectively. The mean quadriceps tensile force after TPLO was significantly greater in the DCO group (3.9 +/- 0.3) than the ICO group (3.3 +/- 0.4) (P = 0.006). Both groups exhibited tibial caudal displacement after TPLO.