Validation of an Experimental Testing Apparatus Simulating the Stance Phase of a Canine Pelvic Limb at Trot in the Normal and the Cranial Cruciate-Deficient Stifle: An In Vitro Kinematic Study

To design an experimental testing apparatus simulating a quasi-static model of the stance phase at a trot for a normal and a cranial cruciate ligament (CCL)-deficient stifle under near physiologic conditions. In vitro biomechanical study. Paired pelvic limbs (n=6) from 3 dogs, weighing 29.5-31 kg. With the limbs mounted in a testing apparatus, the stance phase of gait was simulated with a computerized sequence. Two conditions were evaluated: intact stifle and CCL-deficient stifle. Three-dimensional (3D) kinematics was measured with an optoelectronic system. Vertical reaction forces were also measured. Validation consisted of evaluating intra- and interspecimen variability of the 3D kinematic values of the stifle. Amplitude of motion and peak vertical force (PVF) as well as of kinematic values were also compared with in vivo curves reported in the literature. Mean intra- and interspecimen variability were low for all variables measured in both conditions (normal intact CCL, CCL deficient), and comparable to that reported in the literature. Amplitude of motion and PVF as well as kinematic values were also similar to those reported in vivo although 3D kinematics' values were lower for CCL-deficient stifles in our model. Results show that the testing apparatus generates reproducible motion on a loaded limb in a quasi-static way. Values are representative of the in vivo 3D values reported in the literature. This model could be used to evaluate and compare different surgical techniques, and determine which surgical procedures have the potential to reestablish normal stifle kinematics.