The Effect of Loading, Plantar Ligament Disruption and Surgical Repair on Canine Tarsal Bone Kinematics

Our desire to describe the complex kinematic patterns found in nature often exceeds our ability to record, quantify and characterise them. Constantly faced with technological limitations, investigators may attempt to develop new techniques or reduce the complex motions to more simplified models. Perhaps due to technical limitations, the canine pes is commonly considered as a rigid structure, when in reality, this limb segment is comprised of multiple bones and ligaments and motion can readily be demonstrated during palpation. Despite the potentially important role that tarsal bone kinematics may play in energy conservation mechanisms and pathogenesis of injury or disease, there are no descriptions of normal canine tarsal kinematics during locomotion. A radiolucent cadaveric limb loading device was developed and used in conjunction with a computed tomography based kinematic measurement technique to produce the first description of canine tarsal bone kinematics in three dimensions. Tarsal bones were shown to undergo a complex, yet coordinated patterns of motion that facilitate dorsiflexion of the pes in the normal animal. The same technique was applied to specimens following sequential transection of the plantar ligament and revealed the roles of the various components of this ligament. Complete luxation of the proximal intertarsal joint occurred only after transection of the entire ligament, resulting in an inability to transmit force through this limb segment. The final chapter of this thesis, evaluated the ability of a laterally applied bone plate to re-establish force transmission through this limb segment, providing important information that may help to resolve the open question of what the most appropriate surgical repair technique is in these clinical cases