EFFECT OF UNIPODAL VS BIPODAL STANCE ON RADIOGRAPHIC EVALUATION OF FOREFEET IN HORSES.

Introduction/Purpose: Lifting the contralateral forelimb is often used as a method of restraint in
horses. This experimental study was conducted to evaluate the effect of unipodal vs bipodal
stance on several radiographic parameters in equine forefeet.
Methods: Seven non-lame horses were randomly selected. Lateromedial (LM) and
dorsopalmar (DP) projections were obtained on both forefeet, squarely placed on blocks, using
2 x-ray generators in a fixed lateral and dorsal position. Radiographs of each foot were made
in a bipodal stance, immediately followed by the same protocol in an unipodal stance. Several
measurements were made: distal interphalangeal joint (DIPJ) space width on both projections;
mediolateral joint balance on DP projections; extensor process-to-middle phalangeal condyle
(PE-P2) distance and deep digital flexor tendon (DDFT) angle on LM projections. A matched
pairs design, student’s t-test with a 95% confidence level and ANOVA were used to test for
statistical significance.
Results: Compared to a bipodal stance, lateral DIPJ space width was significantly reduced on
unipodal DP views, whereas mediolateral joint imbalance and to a lesser extent medial DIPJ
space width were significantly increased. The PE-P2 distance as well as the DDFT angle were
significantly increased in unipodal LM views, indicating a higher degree of DIPJ flexion in that
condition.
Discussion/Conclusion: Unipodal stance significantly affects the mediolateral balance of the
DIPJ on DP radiographs and significantly alters the phalangeal axis on LM radiographs. These
findings suggest that stance should be carefully taken into consideration when radiographically
evaluating equine forefeet, especially if assessing foot balance and conformation.