Kinetic and kinematic evaluation of compensatory movements of the head, pelvis and thoraco-lumbar spine associated with asymmetrical weight bearing of the pelvic limbs in dogs

The purposes of this dissertation were to 1) determine ground reaction forces of dogs with mild asymmetrical weight-bearing of the pelvic limbs while trotting and 2) use three-dimensional motion analysis to identify compensatory vertical motion of the head and pelvis, and lateral motion of the thoraco-lumbar spine in dogs with mild asymmetrical weight-bearing of the pelvic limbs while trotting, and 3) use this information to introduce a subjective grading system for the pelvic limbs in dogs. Our hypotheses were that dogs with asymmetric weight bearing demonstrate compensatory motions of the head, pelvis and thoraco-lumbar spine while trotting, and that these motions would have a positive correlation with the degree of weight bearing asymmetry.

Twenty-seven dogs were included in the study. Nine were normal dogs, which had no surgical intervention, 9 dogs had a cranial cruciate ligament transection and tibial plateau leveling osteotomy 3 ± 0.5 years prior to study start, and 9 dogs had a cranial cruciate ligament transection and extracapsular lateral fabellar-tibial suture (modified retinacular imbrications technique) 7 ± 0.5 years prior to study start. A kinematic model was created so that reflective markers placed on the sagittal crest of the skull, the ischiatic tuberosity and 3 points along the thoraco-lumbar spine of each test subject could be tracked over time while trotting. Kinetic and kinematic data were used to characterize weight-bearing asymmetry between the left and right pelvic limbs, and to describe linear vertical displacement of the head and pelvis, and lateral angular displacement of the thoraco-lumbar spine. Maximum, minimum and range of motion values were analyzed for any differences between the pelvic limbs.

Dogs with subtle asymmetric weight bearing of the pelvic limbs demonstrated a greater range of pelvis linear vertical displacement (PLVD) on the side with a greater peak vertical force, and greater thoraco-lumbar lateral angular displacement (TL-LAD) toward the side with a lower peak vertical force while trotting. No differences in mean head linear vertical displacement (HLVD) were detected, and there were no significant correlations between the magnitude of HLVD, PLVD and TL-LAD and the degree of asymmetrical weight bearing of the pelvic limbs.