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  • Author or Editor: Kurt S. Schulz x
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Abstract

Objective—To evaluate areas of articular contact of the proximal portions of the radius and ulna in normal elbow joints of dogs and the effects of axial load on size and location of these areas.

Sample Population—Forelimbs obtained from cadavers of 5 adult mixed-breed dogs.

Procedure—After forelimbs were removed, liquidphase polymethyl methacrylate was applied to articular surfaces of the elbow joint, and limbs were axially loaded. Articular regions void of casting material were stained with water-soluble paint. Relative articular contact areas were determined by computer-assisted image analyses of stained specimens. Repeatability of the technique was evaluated by analyses of casts from bilateral forelimbs of 1 cadaver. Incremental axial loads were applied to left forelimbs from 4 cadavers to determine effects of load on articular contact.

Results—Specific areas of articular contact were identified on the radius, the craniolateral aspect of the anconeus, and the medial coronoid process. The medial coronoid and radial contact areas were continuous across the radioulnar articulation. There was no articular contact of the medial aspect of the anconeus with the central trochlear notch. Coefficients of variation of contact areas between repeated tests and between contralateral limbs was < 20%. Significant overall effects of axial load on contact area or location were not identified.

Conclusions—Three distinct contact areas were evident in the elbow joint of dogs. Two ulnar contact areas were detected, suggesting there may be physiologic incongruity of the humeroulnar joint. There was no evidence of surface incongruity between the medial edge of the radial head and the lateral edge of the medial coronoid process. (Am J Vet Res 2000;61: 1315–1321)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether a full-body spandex garment would alter rectal temperatures of healthy dogs at rest in cool and warm environments.

Design—Prospective study.

Animals—10 healthy dogs.

Procedures—Each dog was evaluated at a low (20° to 25°C [68° to 77°F]) or high (30° to 35°C [86° to 95°F]) ambient temperature while wearing or not wearing a commercially available whole-body spandex garment designed for dogs. Oxygen consumption was measured by placing dogs in a flow-through indirect calorimeter for 90 to 120 minutes. Rectal temperature was measured before dogs were placed in the calorimeter and after they were removed.

Results—Rectal temperature increased significantly more at the higher ambient temperature than at the lower temperature and when dogs were not wearing the garment than when they were wearing it. The specific rate of oxygen consumption was significantly higher at the lower ambient temperature than at the higher temperature.

Conclusions and Clinical Relevance—Results suggest that wearing a snug spandex body garment does not increase the possibility that dogs will overheat while in moderate ambient temperatures. Instead, wearing such a garment may enable dogs to better maintain body temperature during moderate heat loading. These results suggest that such garments might be used for purposes such as wound or suture protection without causing dogs to overheat. (J Am Vet Med Assoc 2004;224:71–74)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare fit and geometry of reconstruction of femoral components of 4 canine cemented total hip replacement implants and determine which implants are most compatible with current principles of cemented arthroplasty.

Sample Population—Paired femurs from 16 adult mixed-breed dogs.

Procedure—Femurs were prepared for femoral stem implantation of either the Bardet, BioMedtrix, Mathys, or Richards II implant. Mediolateral and craniocaudal radiographs were obtained with femoral components in situ. Cross-sectional analysis of implant fit was performed on transected cemented specimens. Computer-aided analyses of digitized images were performed.

Results—The Bardet and Richards II implants reconstructed the original femoral head position significantly better than the other 2 implants. None of the implants allowed neutralization of the implant axis in the sagittal plane or were routinely centralized in the femoral canal. The Bardet implant had the smallest minimum distal tip offset in the sagittal plane. Greatest tip to cortex distance was provided by the Richards II implant in the transverse plane and the Mathys implant in the sagittal plane. The thinnest cement mantle regions for all implants were in the central longitudinal third of the femoral stem.

Conclusions and Clinical Relevance—The Bardet and BioMedtrix implants had stem design characteristics that were most compatible with principles of cemented stem fixation. None of the implants completely satisfied the theoretically optimal conditions of centralization and neutralization of the femoral stem. Innovative design modifications, therefore, may be needed if these conditions are important to the longterm success of canine total hip replacement. (Am J Vet Res 2000;61:1113–1121)

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in American Journal of Veterinary Research

Abstract

Objective—To compare activities of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and matrix metalloproteinase (MMP)-3 and contents of sulfated glycosaminoglycan (S-GAG) in joint fluid obtained from dogs with hip dysplasia (HD) and clinically normal dogs, evaluate correlations among these markers in joint fluid obtained from dogs with HD, and evaluate correlations between each marker and clinical and radiographic variables.

Animals—26 dogs with HD (clinical group) and 43 clinically normal Beagles (control group).

Procedure—Joint fluid was aseptically collected from the hip joints of all dogs. For each dog in the clinical group, age, duration of lameness, radiographic osteoarthritis (OA) score, and Norberg angle in each affected joint were recorded. Activities of IL-1β, IL-6, TNF-α, and MMP-3 and S-GAG contents were measured. Values were compared between groups by use of Mann-Whitney U tests, and the Spearman rank correlation test was used to evaluate correlations among markers and between each marker and clinical or radiographic variables.

Results—Values of all markers were significantly higher for the clinical group, compared with values for the control group. There was a moderate positive correlation between lameness duration and IL-6 activity and a strong negative correlation between the Norberg angle and IL-1β activity.

Conclusions and Clinical Relevance—Analysis of our results indicated that there was a significant increase in markers of OA in dogs with HD. Activities of IL-1β and IL-6 in joint fluid of dogs with HD may be influenced by the severity of laxity in the hip joint and lameness duration, respectively. (Am J Vet Res 2005;66:2028–2033)

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in American Journal of Veterinary Research

Abstract

Objective—To determine effects of incremental radial shortening and subsequent ulnar ostectomies on joint surface contact patterns in a canine elbow joint model.

Sample Population—Paired forelimbs from 9 adult dogs.

Procedure—Joint casting was performed by placement of colored polymethylmethacrylate in the elbow joint cavity and loading in a materials testing system at physiologic angle and load. Joint casting was performed in unaltered specimens, after radial shortening, and after subsequent distal ulnar ostectomy, proximal ulnar ostectomy, and proximal ulnar ostectomy with intramedullary pinning. Computer-aided analysis of photographs of proximal radial and ulnar articular surfaces without joint casts was performed before and after each casting procedure.

Results—All increments of radial shortening changed the size and location of radial and ulnar contact areas. The radial contact area became smaller, the anconeal contact area disappeared, the medial coronoid contact area migrated craniolaterally, and the lateral projection of the coronoid process became a contact area. A proximal ulnar ostectomy stabilized with an intramedullary pin restored normal contact area size and location and restored continuity of the radial and coronoid contact areas across the radioulnar articulation in 6 of 10 specimens. A midshaft ulnar ostectomy, distal to the level of the radioulnar ligament, had no effect on contact patterns. A proximal ulnar ostectomy without stabilization resulted in varus deformity during loading.

Conclusion and Clinical Relevance—Proximal radial shortening, which creates articular step incongruity, changes the location and size of the radioulnar contact areas. Dynamically stabilized ulnar ostectomies proximal to the radioulnar ligament restore contact patterns in vitro . (Am J Vet Res 2001;62:1548–1556)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the distribution of force between the articular surfaces of the humerus and radius and between the humerus and ulna in normal canine forelimbs.

Sample population—12 cadaveric canine right forelimbs.

Procedure—Transarticular force maps were created by placing a tactile array pressure sensor into the elbow joint cavity and loading cadaveric forelimbs in a materials testing system. Mean joint forces were determined at loads of 50, 100, 150, and 200 N.

Results—All tests produced 2 distinct areas of high load that corresponded with the proximal articular surfaces of the radius and ulna. Mean forces for the radial proximal articular surface were slightly but significantly greater than for the ulna, averaging 51% to 52% of total force for all applied loads.

Conclusions and Clinical Relevance—The proximal articular surface of the ulna contributes substantially to load transfer through the canine elbow joint. Abnormalities, which increase this load, might contribute to canine elbow joint dysplasia, specifically fragmentation of the medial coronoid process and osteochondritis dissecans of the medial aspect of the humeral condyle. In the treatment of these conditions, the normal force distribution within the canine elbow joint should be taken into consideration. (Am J Vet Res 2005;66:132–135)

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in American Journal of Veterinary Research

Abstract

Objective—To develop a model for measuring rotary stability of the canine elbow joint and to evaluate the relative contribution of the anconeal process (AN), lateral collateral ligament (LCL), and medial collateral ligament (MCL).

Sample Population—18 forelimbs from 12 canine cadavers.

Procedure—Forelimbs were allocated to 3 experimental groups (6 forelimbs/group). Each intact forelimb was placed in extension at an angle of 135° and cycled 50 times from –16° (pronation) to +28° (supination) in a continuous manner at 2.0 Hz. Cycling was repeated following sectioning of the structure of interest (group 1, AN; group 2, LCL; and group 3, MCL). Torque at –12° (pronation) and +18° (supination) was measured for each intact and experimentally sectioned limb. A Student t test was performed to compare torque values obtained from intact verses experimentally sectioned limbs and for comparison with established criteria for differentiation of primary (≥ 33%), secondary (10 to 33%), and tertiary rotational stabilizers (< 10%).

Results—In pronation, the AN was the only primary stabilizer (65%). For supination, the LCL was a primary stabilizer (48%), AN was a secondary stabilizer (24%), and MCL was a tertiary stabilizer (7%).

Conclusions and Clinical Relevance—With the elbow joint in extension at an angle of 135°, the AN is a primary rotational stabilizer in pronation, and the LCL is a primary stabilizer in supination. Disruption of the AN or LCL may affect rotary range of motion or compromise stability of the elbow joint in dogs. (Am J Vet Res 2002;63:1520–1526)

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in American Journal of Veterinary Research

Abstract

Objective—To compare in vitro mechanical properties of toggle pins and toggle rods used as suture anchors and of 3 suture materials (50-lb monofilament polybutester, No. 5 braided polyester, and 5-mm woven polyester) commonly used as prosthetic ligaments in the repair of hip joint luxation in dogs.

Sample Population—Femoropelvic specimens from the cadavers of 18 dogs.

Procedure—Suture anchors were compared by use of pullout tests. Suture materials were compared by use of monotonic and cyclic tensile tests; cyclic tensile tests were performed with the suture placed over the edge of an aluminum bar to simulate the edge of the femoral bone tunnel. In vitro mechanical properties of the ligament of the femoral head were determined by use of monotonic tensile tests, using boneligament-bone cadaveric specimens. The in vitro mechanical properties of the acetabulum-ligamentfemur complex and of this complex following rupture of the ligament and stabilization with a toggle rod and 5-mm woven polyester were determined by use of compression tests that simulated weight-bearing.

Results—Mechanical properties of the toggle rod were not significantly different from those of the toggle pin. Woven polyester had the longest fatigue life in cyclic testing. Hip joints stabilized with a toggle rod and woven polyester had less than half the strength in vitro of intact joints.

Conclusions and Clinical Relevance—Results suggested that a toggle rod or toggle pin can be used for stabilization of hip joint luxations in dogs. Of the materials tested, braided polyester had the best in vitro mechanical properties. (Am J Vet Res 2001;62: 721–728)

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in American Journal of Veterinary Research

Abstract

Objective—To calculate normative joint angle, intersegmental forces, moment of force, and mechanical power at elbow, antebrachiocarpal, and metacarpophalangeal joints of dogs at a walk.

Animals—6 clinically normal mixed-breed dogs.

Procedure—Kinetic data were collected via a force platform, and kinematic data were collected from forelimbs by use of 3-dimensional videography. Length, location of the center of mass, total mass, and mass moment of inertia about the center of mass were determined for each of 4 segments of the forelimb. Kinematic data and inertial properties were combined with vertical and craniocaudal ground reaction forces to calculate sagittal plane forces and moments across joints of interest throughout stance phase. Mechanical power was calculated as the product of net joint moment and the angular velocity. Joint angles were calculated directly from kinematic data.

Results—All joint intersegmental forces were similar to ground reaction forces, with a decrease in magnitude the more proximal the location of each joint. Flexor moments were observed at metacarpophalangeal and antebrachiocarpal joints, and extensor moments were observed at elbow and shoulder joints, which provided a net extensor support moment for the forelimb. Typical profiles of work existed for each joint.

Conclusions and Clinical Relevance—For clinically normal dogs of a similar size at a walk, inverse dynamic calculation of intersegmental forces, moments of force, and mechanical power for forelimb joints yielded values of consistent patterns and magnitudes. These values may be used for comparison in evaluations of gait in other studies and in treatment of dogs with forelimb musculoskeletal disease. (Am J Vet Res 2003;64:609–617)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of sliding and wedge osteotomies of the humerus on the joint surface contact areas in anatomically normal elbow joints of dogs.

Sample Population—Left thoracic limbs from 5 skeletally mature mixed-breed canine cadavers.

Procedure—Joint casting was performed by placement of colored polymethylmethacrylate in the elbow joint cavity followed by loading in a materials testing system at physiologic angle and load. Joint casting was performed in unaltered specimens, after 10° medial opening wedge osteotomy, and after lateral sliding osteotomy of the proximal portion of the humerus. Computer-aided analysis of photographs of proximal radial and ulnar articular surfaces after each casting procedure was performed.

Results—The lateral sliding humeral osteotomy and 10° medial opening wedge osteotomy significantly altered joint surface contact regions of the canine elbow joint. Osteotomies resulted in a reduction in the size of the radial, ulnar, and combined radioulnar contact areas. Both osteotomies also resulted in craniolateral migration of the radial contact area and craniomedial recession of the ulnar contact area. Although the reduction in ulnar contact area with these treatments is consistent with our hypotheses, the reduction in radial contact area was not anticipated.

Conclusions and Clinical Relevance—Humeral osteotomies alter joint surface contact areas of the canine elbow joint in vitro. Humeral osteotomies may decrease contact areas on the diseased region of the joint in dogs with elbow dysplasia; however, the overall decrease in joint surface contact area suggests that these procedures may induce focal increases in pressure that may cause iatrogenic cartilage damage when applied in vivo. (Am J Vet Res 2003;64:506–511)

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in American Journal of Veterinary Research