Interobserver Variability of Joint Orientation Lines in Dogs with Antebrachial Deformities

Introduction: The current Paley derived methodology for determining the centre of rotation of angulation (CORA), relies on defining joint orientation lines (JOL) and joint orientation angles (JOA) in both affected and contralateral limbs. Reproducibility of these measurements has not been assessed for dogs with antebrachial deformity.

Materials and Methods: Radiographic studies from 23 nonchondrodystrophic dogs with unilateral antebrachial limb deformity were analyzed. Three observers marked the JOL on orthogonal radiographs of the normal and affected limbs. Anatomic axes were marked on the normal limb projections, and JOA was measured from the intersecting lines. JOL from each observer were superimposed, and their orientation was quantified relative to a common mechanical axis. Agreement between observer measurements was assessed using intraclass correlation coefficients (ICC).

Results: Interobserver ICC for the JOL of the affected limb ranged from 0.919 to 0.985, indicating excellent correlation. ICC for normal limb JOL ranged from 0.626 to 0.995, indicating good to excellent correlation. JOA ICC for the normal limbs were 0.24 to 0.806 indicating fair to good correlation.

Discussion/Conclusion: Whereas interobserver agreement of defining JOL was excellent for limbs with deformity, there were greater variations of repeatability for the JOL for normal limbs. These variations may result in different magnitudes of surgical corrections between surgeons.

Acknowledgment: There was no proprietary interest or funding provided for this project.