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in Journal of the American Veterinary Medical Association

Abstract

Objective

To ascertain effects of x-ray beam centering and limb position on apparent congruity of a normal cubital joint (elbow).

Animals

6 skeletally mature male Treeing Walker Coonhounds without physical, radiographic, or gross evidence of elbow abnormalities.

Procedure

Relative movement among humerus, radius, and ulna and measured joint space width on mediolateral and craniocaudal radiographic views was compared, using various x-ray beam centering and limb positions.

Results

Highest agreement and greatest certainty on subjective determination of congruity was for the flexed 90° mediolateral radiographic view with the x-ray beam centered on the elbow. Distortion artifact of the proximal ulnar measurements was significant when the x-ray beam was centered on the midpoint of the radius. On the mediolateral view, the humeroradial joint space became significantly wide when the elbow was flexed. On the craniocaudal view, maximal humeroradial joint space width was obtained when the x-ray beam bisected the angle of the joint or was angled +30° toward the humerus.

Conclusions

Artifact distortion of joint width affected objective and subjective assessment of elbow congruity when the limb was placed in extreme flexion or extension or when the x-ray beam was not centered over the area of interest. Optimal visualization of the humeroradial joint space on the craniocaudal view was achieved when the x-ray beam bisected the angle of the elbow or was slightly angled toward the humerus.

Clinical Relevance

Elbow congruity was best assessed on the flexed 90° lateral radiographic view with the x-ray beam centered on the joint. (Am J Vet Res 1998;59:1351–1357)

Free access
in American Journal of Veterinary Research

Objective

To determine the usefulness of 5 radiographic projections of the elbow joint for identification of fragmented coronoid process (FCP) and associated secondary degenerative changes in dogs.

Design

Longitudinal clinical study.

Animals

19 dogs suspected of having FCP (7 dogs, 1 elbow joint; 12 dogs, both elbow joints).

Procedure

5 radiographic projections were obtained before and after surgery for all elbow joints on which exploratory arthrotomy was performed because of suspected FCP. Radiographs obtained before surgery were compared with radiographs obtained after surgery and radiographs taken of the excised fragments. Each projection was evalated for its utitility in definitively identifying FCP and 7 specific degenerative changes. Interevaluator agreement, use of each radiographic projection for definitively identifying a feature, and ability of the 4 evaluators to definitively identify a feature were analyzed.

Results

The craniolateral-caudomedial oblique (Cr15L-CdMO) projection had a significantly higher sensitivity for definitively identifying FCP, compared with the other 4 projections. Interevaluator and kappa agreement for the 5 projections did not differ significantly among the 7 degenerative changes evaluated. The radiographic projection with the highest sensitivity and specificity for detection of a particular degenerative change varied by feature.

Clinical Implications

Of the 5 radiographic projections evaluated, the Cr15L-CdMO projection provided the highest sensitivity and was the best projection to use for definitively identifying FCP. The craniocaudal, Cr15L-CdMO, and mediolateral projections most reliably allowed for identification of secondary degenerative changes. (J Am Vet Med Assoc 1999;214:52–58)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine relative effects of ring diameter and wire tension on axial biomechanical properties of 4-ring circular external skeletal fixator constructs.

Sample Population—4-ring circular external skeletal fixator constructs and artificial bone models.

Procedure—4-ring constructs were assembled, using 50-, 66-, 84-, or 118-mm-diameter rings. Two 1.6-mm-diameter fixation wires were attached to opposing surfaces of each ring at intersection angles of 90o and placed through a gap-fracture bone model. Three examples of each construct were loaded in axial compression at 7 N/s to a maximum load of 400 N at each of 4 wire tensions (0, 30, 60, and 90 kg). Response variables were determined from resulting load-displacement curves (construct stiffness, load at 1 mm of displacement, displacement at 400 N).

Results—Ring diameter and wire tension had a significant effect on all response variables and had a significant interaction for construct stiffness and displacement at 400 N. Significant differences within all response variables were seen among all 4 ring diameters and all 4 wire tensions. As ring diameter increased, effect of increasing wire tension on gap stiffness and gap displacement at 400 N decreased. Ring diameter had a greater effect than wire tension on all response variables.

Conclusions and Clinical Relevance—Although effects of wire tension decrease as ring diameter increases, placing tension on wires in larger ring constructs is important because these constructs are inherently less stiff. The differential contribution of ring diameter, wire tension, and their interactions must be considered when using circular external skeletal fixators. (Am J Vet Res 2001;62:1025–1030)

Full access
in American Journal of Veterinary Research