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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 repeatability and accuracy of polymer replicas of small, medium, and large long bones of small animals fabricated by use of 2 low-end and 2 high-end 3-D printers.

SAMPLE Polymer replicas of a cat femur, dog radius, and dog tibia were fabricated in triplicate by use of each of four 3-D printing methods.

PROCEDURES 3-D renderings of the 3 bones reconstructed from CT images were prepared, and length, width of the proximal aspect, and width of the distal aspect of each CT image were measured in triplicate. Polymer replicas were fabricated by use of a high-end system that relied on jetting of curable liquid photopolymer, a high-end system that relied on polymer extrusion, a triple-nozzle polymer extrusion low-end system, and a dual-nozzle polymer extrusion low-end system. Polymer replicas were scanned by use of a laser-based coordinate measurement machine. Length, width of the proximal aspect, and width of the distal aspect of the scans of replicas were measured and compared with measurements for the 3-D renderings.

RESULTS 129 measurements were collected for 34 replicas (fabrication of 1 large long-bone replica was unsuccessful on each of the 2 low-end printers). Replicas were highly repeatable for all 3-D printers. The 3-D printers overestimated dimensions of large replicas by approximately 1%.

CONCLUSIONS AND CLINICAL RELEVANCE Low-end and high-end 3-D printers fabricated CT-derived replicas of bones of small animals with high repeatability. Replicas were slightly larger than the original bones.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate accuracy of articular surfaces determined by use of 2 perpendicular CT orientations, micro-CT, and laser scanning.

SAMPLE

23 cat cadavers.

PROCEDURES

Images of antebrachia were obtained by use of CT (voxel size, 0.6 mm) in longitudinal orientation (CTLO images) and transverse orientation (CTTO images) and by use of micro-CT (voxel size, 0.024 mm) in a longitudinal orientation. Images were reconstructed. Craniocaudal and mediolateral length, radius of curvature, and deviation of the articular surface of the distal portion of the radius of 3-D renderings for CTLO, CTTO, and micro-CT images were compared with results of 3-D renderings acquired with a laser scanner (resolution, 0.025 mm).

RESULTS

Measurement of CTLO and CTTO images overestimated craniocaudal and mediolateral length of the articular surface by 4% to 10%. Measurement of micro-CT images underestimated craniocaudal and mediolateral length by 1%. Measurement of CTLO and CTTO images underestimated mediolateral radius of curvature by 15% and overestimated craniocaudal radius of curvature by > 100%; use of micro-CT images underestimated them by 3% and 5%, respectively. Mean ± SD surface deviation was 0.26 ± 0.09 mm for CTLO images, 0.30 ± 0.28 mm for CTTO images, and 0.04 ± 0.02 mm for micro-CT images.

CONCLUSIONS AND CLINICAL RELEVANCE

Articular surface models derived from CT images had dimensional errors that approximately matched the voxel size. Thus, CT cannot be used to plan conforming arthroplasties in small joints and could lack precision when used to plan the correction of a limb deformity or repair of a fracture.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate the 3-D geometry of canine pelves and to characterize the long-term effects of juvenile pubic symphysiodesis (JPS) on pelvic geometry by comparing the pelvic configuration between littermates that did and did not undergo the procedure.

ANIMALS 24 Labrador Retriever, Golden Retriever, or Labrador Retriever–Golden Retriever crossbred service dogs from 13 litters.

PROCEDURES At 16 weeks old, puppies with a hip joint distraction index ≥ 0.5 were randomly assigned to undergo thermal JPS (n = 9), mechanical JPS (7), or a sham (control) surgical procedure (8). Ten years later, each dog underwent a CT scan of the pelvic region. Modeling software was used to create 3-D reconstructions from the CT scans, and various pelvic measurements were made and compared among the 3 treatments.

RESULTS Compared with the control treatment, thermal and mechanical JPS increased the hemipelvis acetabular angle by 4°, the acetabular angle of lateral opening by 5°, and the orientation of the medial acetabular wall in a transverse plane by 6°, which indicated that JPS increased dorsal femoral head coverage by the acetabulum. Both JPS procedures decreased the pelvic canal area by approximately 20% and acetabular inclination by 6° but did not alter acetabular retroversion.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that thermal and mechanical JPS were equally effective in altering the 3-D pelvic geometry of dogs. These findings may help guide future studies of alternatives for optimizing canine pelvic anatomy to minimize the risk of hip dysplasia and associated osteoarthritis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the effect of computed tomography (CT) scan protocols (radiation amounts) and fabrication methods on biomodel accuracy and variability.

Sample—Cadaveric femur of a Basset Hound.

Procedures—Retroreconstructions (n = 158) were performed of 16 original scans and were visually inspected to select 17 scans to be used for biomodel fabrication. Biomodels of the 17 scans were made in triplicate by use of 3 freeform fabrication processes (stereolithography, fused deposition modeling, and 3-D printing) for 153 models. The biomodels and original bone were measured by use of a coordinate measurement machine.

Results—Differences among fabrication methods accounted for 2% to 29% of the total observed variation in inaccuracy and differences among method-specific radiation configurations accounted for 4% to 44%. Biomodels underestimated bone length and width and femoral head diameter and overestimated cortical thickness. There was no evidence of a linear association between thresholding adjustments and biomodel accuracy. Higher measured radiation dose led to a decrease in absolute relative error for biomodel diameter and for 4 of 8 cortical thickness measurements.

Conclusions and Clinical Relevance—The outside dimensions of biomodels have a clinically acceptable accuracy. The cortical thickness of biomodels may overestimate cortical thickness. Variability among biomodels was caused by model fabrication reproducibility and, to a lesser extent, by the radiation settings of the CT scan and differences among fabrication methods.

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To evaluate the accuracy of 2 radiographic methods used to assess tibial plateau slope (TPS) in dogs and evaluate effects of film digitization and radiographic beam placement on TPS measurements.

Sample Population—16 hind limbs from dog cadavers weighing > 20 kg.

Procedures—Radiographs of tibiae were made with the radiographic beam centered over the stifle joint and midshaft of the tibia. Tibiae were collected, the femorotibial contact area was determined, and slope of the medial tibial condyle in relation to the tibial shaft was measured. Radiographs were digitized. Slope of the medial tibial condyle was measured on printed and digitized radiographs read in random order by 6 examiners unaware of anatomic measurements. Three examiners used a conventional measuring technique, and 3 examiners used an alternative measuring technique.

Results—Anatomic measurements were significantly higher than radiographic measurements made by use of the conventional interpretation method but did not differ from radiographic measurements made by use of the alternate method. Measurements from printed radiographs were lower than measurements from digitized radiographs for the 4 most experienced examiners.

Conclusions and Clinical Relevance—Measurements made by use of a line tangential to the cranial, linear portion of the medial tibial condyle at the femorotibial contact point were accurate measurements of the anatomic TPS. Measurements made by use of the conventional TPS measurement method underestimated the anatomic TPS. Measurements made on digitized radiographs were typically more accurate than measurements made on printed radiographs. (Am J Vet Res 2003;64:586–589)

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

Abstract

Objective—To compare measurements obtained by use of a universal plastic goniometer (UG) and an electrogoniometer (EG) and from radiographs and to compare joint motion in German Shepherd Dogs and Labrador Retrievers.

Animals—12 healthy adult German Shepherd Dogs and data previously collected from 16 healthy adult Labrador Retrievers.

Procedures—German Shepherd Dogs were sedated. One investigator then measured motion of the carpal, cubital (elbow), shoulder, tarsal, stifle, and hip joints of the sedated dogs. Measurements were made in triplicate with a UG and an EG. Radiographs were taken of all joints in maximal flexion and extension. Values were compared between the UG and EG and with values previously determined for joints of 16 Labrador Retrievers.

Results—An EG had higher variability than a UG for all dogs. The EG variability appeared to result from the technique for the EG. German Shepherd Dogs had lower values in flexion and extension than did Labrador Retrievers for all joints, except the carpal joints. German Shepherd Dogs had less motion in the tarsal joints, compared with motion for the Labrador Retrievers, but had similar motion in all other joints.

Conclusions and Clinical Relevance—A UG is reliable for obtaining measurements in German Shepherd Dogs. There was higher variability for the EG than for the UG, and an EG cannot be recommended for use.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare application time, accuracy of tibial plateau slope (TPS) correction, presence and magnitude of rotational and angular deformities, and mechanical properties of 5 canine tibial plateau leveling methods.

Sample Population—27 canine tibial replicas created by rapid prototyping methods.

Procedure—The application time, accuracy of TPS correction, presence and magnitude of rotational and angular deformation, and construct axial stiffness of 3 internal fixation methods (tibial plateau leveling osteotomy, tibial wedge osteotomy, and chevron wedge osteotomy [CWO]) and 2 external skeletal fixation (ESF) methods (hinged hybrid circular external fixation and wedge osteotomy linear fixation [WOLF]) were assessed.

Results—Mean bone model axial stiffness did not differ among methods. Mean application time was more rapid for WOLF than for other methods. Mean TPSs did not differ from our 5° target and were lower for ESF methods, compared with internal fixation methods. Mean postoperative rotational malalignment did not differ from our target or among groups. Mean postoperative medio-lateral angulation did not differ from our target, except for CWO. Internal fixation methods lead to axially stiffer constructs than ESF methods. Reuse of ESF frames did not lead to a decrease in axial stiffness.

Conclusions and Clinical Relevance—The 5 tibial plateau leveling methods had acceptable geometric and mechanical properties. External skeletal fixation methods were more accurate as a result of precise data available for determining the exact magnitude of correction required to achieve a 5° TPS.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To investigate in vitro carboplatin release from 6 carrier media.

SAMPLE 6 carboplatin-containing carrier media.

PROCEDURES An in vitro release study was performed with 6 commercially available carrier media: a hemostatic gelatin sponge, a poloxamer copolymer gel, and 2 sizes (3 and 4.8 mm in diameter) of beads molded from each of 2 commercial calcium sulfate products. All carrier media contained 10 mg of carboplatin. Carrier media specimens were placed in 37°C PBS solution for 96 hours. Carboplatin concentrations in PBS solution were measured by use of high-performance liquid chromatography at 15 time points to calculate the amount and proportion of carboplatin released from each specimen.

RESULTS Peak release of carboplatin from the poloxamer copolymer gel and hemostatic gelatin sponge were achieved after 4 and 20 hours, respectively. Maximum release did not differ significantly between the poloxamer copolymer gel and hemostatic gelatin sponge, but both released significantly more carboplatin within 96 hours than did both of the commercial calcium sulfate products. The poloxamer copolymer gel released 99% of the carboplatin, and the hemostatic gelatin sponge released 68.5% of the carboplatin. Peak release of carboplatin from the calcium sulfate beads was not reached within 96 hours.

CONCLUSIONS AND CLINICAL RELEVANCE In this study, carboplatin release from the hemostatic gelatin sponge was incomplete. The poloxamer copolymer gel and hemostatic gelatin sponge released carboplatin rapidly in vitro, whereas calcium sulfate beads did not.

Full access
in American Journal of Veterinary Research