Effect of limb positioning on the radiographic appearance of the distal and proximal interphalangeal joint spaces of the forelimbs of horses during evaluation of dorsopalmar radiographs

Abstract

Objective-To determine the effect of limb positioning on the radiographic appearance of the distal and proximal interphalangeal joint spaces of the forelimbs of horses during evaluation of dorsopalmar radiographs. Design-Evaluation study. Animals-14 forelimbs from 9 adult horses. Procedures-Each horse was in standing position with its forelimbs positioned on blocks. Dorsopalmar radiographs of each foot were obtained with the forelimbs positioned squarely (the metacarpus of both forelimbs was perpendicular to the ground as determined by visual examination [abducted 0°]; baseline) and abducted 5° and 10°. The width of the space at the medial and lateral aspects of the distal and proximal interphalangeal joints (medial and lateral joint space width, respectively) was measured. Mediolateral joint balance was calculated as the difference between the widths of the lateral and medial joint spaces, and joint space width and mediolateral joint balance were compared among all 3 positions. Results-As the extent of limb abduction increased, the medial aspect of the proximal and distal interphalangeal joints became narrower, compared with the corresponding lateral aspect of those joints. For both the distal and proximal interphalangeal joints, the mediolateral joint balance differed significantly among all limb positions. Conclusions and Clinical Relevance-Forelimb position significantly affected the mediolateral joint balance of the interphalangeal joints of horses. Thus, it is crucial that the forelimbs of horses be squarely positioned when dorsopalmar radiographs are obtained for accurate evaluation of interphalangeal joint space and balance.