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  • Author or Editor: Denis J. Marcellin-Little x
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Abstract

Objective—To investigate the influence of varying morphological parameters on canine stifle joint biomechanics by use of a 3-D rigid-body canine pelvic limb computer model that simulated an intact and cranial cruciate ligament (CrCL)–deficient stifle joint across the stance phase of gait at a walk.

Sample—Data from computer simulations.

Procedures—Computer model morphological parameters, including patellar ligament insertion location, tibial plateau angle (TPA), and femoral condyle diameter (FCD), were incrementally altered to determine their influence on outcome measures (ligament loads, relative tibial translation, and relative tibial rotation) during simulation of the stance phase of gait at a walk. Outcome measures were assessed for each scenario and compared between an intact and CrCL-deficient stifle joint with the sensitivity index (the percentage change in outcome measure divided by the percentage change in input parameter).

Results—In a CrCL-intact stifle joint, ligament loads were most sensitive to TPA. In a CrCL-deficient stifle joint, outcome measures were most sensitive to TPA with the exception of caudal cruciate ligament and lateral collateral ligament loads, which were sensitive to FCD and TPA. Relative tibial translation was sensitive to TPA and patellar ligament insertion location, whereas relative tibial rotation was most sensitive to TPA.

Conclusions and Clinical Relevance—The computer model sensitivity analyses predicted that individual parameters, particularly TPA and FCD, influence stifle joint biomechanics. Therefore, tibial and femoral morphological parameters may affect the likelihood, prevention, and management of CrCL deficiency.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To investigate the influence of 4 biomechanical parameters on canine cranial cruciate ligament (CrCL)-intact and -deficient stifle joints.

SAMPLE Data for computer simulations of a healthy 5-year-old 33-kg neutered male Golden Retriever in a previously developed 3-D rigid body pelvic limb computer model simulating the stance phase during walking.

PROCEDURES Canine stifle joint biomechanics were assessed when biomechanical parameters (CrCL stiffness, CrCL prestrain, body weight, and stifle joint friction coefficient) were altered in the pelvic limb computer simulation model. Parameters were incrementally altered from baseline values to determine the influence on stifle joint outcome measures (ligament loads, relative tibial translation, and relative tibial rotation). Stifle joint outcome measures were compared between CrCL-intact and -deficient stifle joints for the range of parameters evaluated.

RESULTS In the CrCL-intact stifle joint, ligament loads were most sensitive to CrCL prestrain. In the CrCL-deficient stifle joint, ligament loads were most sensitive to body weight. Relative tibial translation was most sensitive to body weight, whereas relative tibial rotation was most sensitive to CrCL prestrain.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, computer model sensitivity analyses predicted that CrCL prestrain and body weight influenced stifle joint biomechanics. Cranial cruciate ligament laxity may influence the likelihood of CrCL deficiency. Body weight could play an important role in management of dogs with a CrCL-deficient stifle joint.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effects of tibial plateau leveling osteotomy (TPLO) on canine stifle joint biomechanics in a cranial cruciate ligament (CrCL)–deficient stifle joint by use of a 3-D computer model simulating the stance phase of gait and to compare biomechanics in TPLO-managed, CrCL-intact, and CrCL-deficient stifle joints.

Sample—Computer simulations of the pelvic limb of a Golden Retriever.

Procedures—A previously developed computer model of the canine pelvic limb was used to simulate TPLO stabilization to achieve a tibial plateau angle (TPA) of 5° (baseline value) in a CrCL-deficient stifle joint. Sensitivity analysis was conducted for tibial fragment rotation of 13° to −3°. Ligament loads, relative tibial translation, and relative tibial rotation were determined and compared with values for CrCL-intact and CrCL-deficient stifle joints.

Results—TPLO with a 5° TPA converted cranial tibial translation to caudal tibial translation and increased loads placed on the remaining stifle joint ligaments, compared with results for a CrCL-intact stifle joint. Lateral collateral ligament load was similar, medial collateral ligament load increased, and caudal cruciate ligament load decreased after TPLO, compared with loads for a CrCL-deficient stifle joint. Relative tibial rotation after TPLO was similar to that of a CrCL-deficient stifle joint. Stifle joint biomechanics were affected by TPLO fragment rotation.

Conclusions and Clinical Relevance—In the model, stifle joint biomechanics were partially improved after TPLO, compared with CrCL-deficient stifle joint biomechanics, but TPLO did not fully restore CrCL-intact stifle joint biomechanics. Overrotation of the tibial fragment negatively influenced stifle joint biomechanics by increasing caudal tibial translation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To design and fabricate fiberglass-reinforced composite (FRC) replicas of a canine radius and compare their mechanical properties with those of radii from dog cadavers.

Sample—Replicas based on 3 FRC formulations with 33%, 50%, or 60% short-length discontinuous fiberglass by weight (7 replicas/group) and 5 radii from large (> 30-kg) dog cadavers.

Procedures—Bones and FRC replicas underwent nondestructive mechanical testing including 4-point bending, axial loading, and torsion and destructive testing to failure during 4-point bending. Axial, internal and external torsional, and bending stiffnesses were calculated. Axial pullout loads for bone screws placed in the replicas and cadaveric radii were also assessed.

Results—Axial, internal and external torsional, and 4-point bending stiffnesses of FRC replicas increased significantly with increasing fiberglass content. The 4-point bending stiffness of 33% and 50% FRC replicas and axial and internal torsional stiffnesses of 33% FRC replicas were equivalent to the cadaveric bone stiffnesses. Ultimate 4-point bending loads did not differ significantly between FRC replicas and bones. Ultimate screw pullout loads did not differ significantly between 33% or 50% FRC replicas and bones. Mechanical property variability (coefficient of variation) of cadaveric radii was approximately 2 to 19 times that of FRC replicas, depending on loading protocols.

Conclusions and Clinical Relevance—Within the range of properties tested, FRC replicas had mechanical properties equivalent to and mechanical property variability less than those of radii from dog cadavers. Results indicated that FRC replicas may be a useful alternative to cadaveric bones for biomechanical testing of canine bone constructs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the intra- and interobserver repeatability of 2-dimensional (2-D) kinematic analysis of walk and sit-to-stand motions in dogs.

Animals—10 healthy adult Labrador Retrievers.

Procedures—10 dogs were filmed during walk and sit-to-stand motions. Five trials were recorded for each dog, 3 of which were digitized. Two observers manually marked 15 landmarks on each frame during the motions of interest for these 3 trials. Each observer repeated the procedure approximately 1 week later. The 2-D joint angles were calculated. Intra- and interobserver coefficients of multiple correlations (CMCs) were calculated for each joint angle–time history.

Results—Intraobserver repeatability, assessed as the mean CMCs of 12 joint angle measurements made for 10 dogs by 2 observers, was good or excellent in 23 of 24 (96%) mean CMCs of the joints measured. Interobserver variation, assessed by comparing CMCs of measurements made by 2 observers on 10 dogs on 2 days, was good or excellent in 161 of 240 (67%) CMCs of joints measured.

Conclusions and Clinical Relevance—Intraobserver repeatability of 2-D kinematic measurements made on digitized videotapes was excellent. Interobserver repeatability of these measurements was acceptable.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the impact of partial immersion in water on vertical ground reaction force (vGRF) and vGRF distribution in dogs.

Animals—10 healthy adult dogs.

Procedures—Weight placed on each limb of each dog was measured 3 times (1 scale/limb). Dogs were then immersed in water to the level of the tarsal, stifle, and hip joints, and vGRFs were measured. Coefficients of variation for triplicate measurements were calculated. Mixed-effects ANOVAs were used to compare the vGRF for thoracic versus pelvic limbs and the vGRF at various immersion levels as well as the vGRF distributions among limbs at various immersion levels.

Results—Mean ± SD vGRF before immersion was 249 ± 34 N. It was significantly decreased by 9% after immersion to the tarsal joints (227 ± 32 N), by 15% after immersion to the stifle joints (212 ± 21 N), and by 62% after immersion to the hip joints (96 ± 20 N). The vGRFs were significantly higher for the thoracic limbs than for the pelvic limbs before immersion and at all immersion levels. Dogs placed 64% of their weight on the thoracic limbs before immersion. That ratio did not differ significantly after immersion to the tarsus (64%) or stifle (63%) joints, but was significantly larger after immersion to the hip joints (71%).

Conclusions and Clinical Relevance—vGRF decreased as the depth of immersion increased. The thoracic limb-to-pelvic limb vGRF ratio was unchanged in dogs after immersion to the tarsal or stifle joints, but it increased after immersion to the hip joints.

Full access
in American Journal of Veterinary Research