An experimental radiographic study on the changes of stifle and tarsal joint angles related to passive hip joint...

To investigate the relationships between hindlimb joints angles under the passive movement of hip joints within a relatively wide range of motion in anesthetized Beagles.

9 hindlimbs of 5 clinically normal adult Beagles were included from September 2022 through August 2023. The tested hindlimb was positioned horizontally, with the dog under general anesthesia and muscle relaxation. Unforced angle (UA; when the paw was unforced), forced angle range (FAR; when the paw was under constant pushing/pulling force), and UA range (UAR; when the forces applied to the paw had been withdrawn) of the stifle and tarsal joints were evaluated using radiographic analysis while the hip joint angle was passively adjusted from 70° to 170°. Linear regression analysis was used to assess the relationships between hip, stifle, and tarsal joint angles.

Significantly strong linear relationships (adjusted R2 > 0.7) were found for hip-stifle and hip-tarsal in UA, UAR, and when the paw was pushed with the hip joint angle exceeding 120° (FAR-push > 120°). The FAR of stifle and tarsal joints changed with the hip joint angle. Additionally, significantly strong linear relationships (adjusted R2 > 0.85) were found for stifle-tarsal in UA, UAR, and when a constant push force was applied on the paw (FAR-push).

This research revealed the linear relationships between canine hindlimb joint angles in the sagittal plane under specific circumstances as well as the narrowing of the FAR of stifle and tarsal joints when hip joint angle exceeds 120°.

The findings on linkage mechanism-related relationships in hindlimb joints angles from this research may contribute to a better understanding of orthopedic and rehabilitation practices.