Development of a Canine Stifle Computer Model to Evaluate Cranial Cruciate Ligament Deficiency

Abstract

The objective of this study was to develop a three-dimensional (3D) quasi-static rigid body canine pelvic limb computer model simulating a cranial cruciate ligament (CrCL) intact and CrCL-deficient stifle during walking stance to describe stifle biomechanics. The model was based on a five-year-old neutered male Golden Retriever (33 kg) with no orthopedic or neurologic disease. Skeletal geometry and ligament anatomy determined from computed tomography (CT), optimized muscle forces, motion capture kinematics, and force platform ground reaction forces were used to develop the model. Ligament loads, tibial translation, tibial rotation, and femoromeniscal contact forces were compared across the intact and CrCL-deficient stifle. The CrCL was found to be the primary intact stifle load-bearing ligament, and the caudal cruciate ligament was the primary CrCL-deficient stifle load-bearing ligament. Normalized tibial translation and rotation were 0.61 mm/kg and 0.14 degrees/kg, respectively. Our model confirmed that the CrCL stabilizes the intact stifle and limits tibial translation and rotation. Model verification was confirmed through agreement with experimentally measured kinematics and previous in vivo, in vitro, and mathematical model studies. Parametric analysis indicated outcome measure sensitivity to ligament pre-strain. Computer modeling could be useful to further investigate stifle biomechanics associated with surgical stabilization techniques.

Canine stifle joint biomechanics associated with tibial plateau leveling osteotomy predicted by use of a computer model

“…To develop the model, the dog was walked on a leash in a straight line; motion-capture kinematics and force platform kinetics were collected during the stance phase of a walking gait. 22 Inverse-dynamics analysis was conducted to determine pelvic limb joint reaction forces and moments. 22 Pelvic limb muscle forces that crossed the stifle joint were represented as linear force vectors following each respective muscle path (n = 22 muscles), and each muscle force was calculated throughout the stance phase by means of the minimization of maximal muscle stress strategy 22 where M is the stifle reaction moment determined via inverse-dynamics analysis, F i is the muscle force, and r i is the moment arm of muscle i.…”

“…Muscle forces were constrained so that they did not exceed 60% of maximal contraction force. 22,27 Ligaments were represented as tension-only elements that carried a load when stretched beyond their neutral length, as determined by use of the following equations 28 :…”

“…22 Femoromeniscal contact equation constants used in the present study were as follows 22 : k = 1,500 N/mm, e = 1.1, cmax = 0.5 N•s/mm, and dmax = 0.8 mm. Penetration between the tibia and femur and between the patella and femur were prevented, with contact represented by use of this equation.…”

“…21 Computer simulation models of the canine pelvic limb have been used to parametrically investigate biomechanics of intact and CrCL-deficient stifle joints during the stance phase of gait. [22][23][24][25][26] These models have predicted an increase in CaCL loads in CrCL-deficient stifle joints. Furthermore, computer simulation models of the canine pelvic limb have been used to predict sensitivity of stifle joint biomechanics to ligament prestrain, TPA, and femoral condyle diameter.…”

“…Furthermore, computer simulation models of the canine pelvic limb have been used to predict sensitivity of stifle joint biomechanics to ligament prestrain, TPA, and femoral condyle diameter. 22,23,26 The purposes of the present study were to implement TPLO stabilization into a previously developed quasistatic 3-D computer simulation model of a canine pelvic limb; evaluate loading patterns of stifle joint ligaments, RTT, and RTR; and investigate the influence of tibial fragment rotation angle in the sagittal plane on stifle joint biomechanics. We hypothesized that TPLO would reduce cranial tibial translation and internal tibial rotation, compared with that for a CrCL-deficient stifle joint, and result in ligament loads with values similar to those for a CrCL-intact stifle joint.…”