Force Plate Gait Analysis and Clinical Results after Tibial Plateau Levelling Osteotomy for Cranial Cruciate Ligament Rupture in Small Breed Dogs.

OBJECTIVE: The aim of this study was to evaluate objective limb function using force plate gait analysis after tibial plateau levelling osteotomy (TPLO) in small breed dogs with cranial cruciate ligament rupture (CCLR). MATERIALS AND METHODS: Small breed dogs (15 kg or less) with unilateral CCLR treated with TPLO were evaluated using symmetry index (SI) of peak vertical force (PVF), vertical impulse and vector magnitude at PVF performed preoperatively and at 1, 2, 4 and 6 months postoperatively after routine TPLO surgery. RESULTS: Twelve dogs met the inclusion criteria. Hindlimb function was markedly improved after TPLO, with all three postoperative SI significantly higher after a month than preoperative values (p < 0.01). At 2 months after surgery, the SI was nearly normalized to 1.0 (preoperative SI: 0.50 ± 0.20, 0.44 ± 0.19 and 0.51 ± 0.19, and 2 months postoperative SI: 0.92 ± 0.16, 0.90 ± 0.18 and 0.92 ± 0.16 respectively). Complications were noted in two dogs (fibular fracture and a partial implant failure), neither of which required a revision surgery for acceptable functional recovery. CONCLUSION: The objective limb function of the affected hindlimb improved continuously after surgery and reached a near normal value at 6 months after surgery. It was suggested that TPLO for small breed dogs had good outcomes based on force plate gait analysis.

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° ± 1.9° and 6.1° ± 1.6°, respectively, and those in the DCO group were 29.8° ± 2.4° and 6.8° ± 0.9°, 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. CLINICAL RELEVANCE: The tensile force of the quadriceps muscles changed in accordance with the centre of the osteotomy in TPLO. The DCO group had increased tensile force, which may cause patellar ligament thickening after TPLO. Setting the postoperative TPA at 6° may cause excessive rotation in patients with a normal tensile force of the stifle flexor muscles.