The Effect of Sliding Humeral Osteotomy (SHO) on Frontal Plane Thoracic Limb Alignment: An Ex Vivo Canine Cadaveric Study.

OBJECTIVE

To determine the effect of sliding humeral osteotomy (SHO) on frontal plane thoracic limb alignment in standing and recumbent limb positions.

STUDY DESIGN

Canine cadaveric study.

SAMPLE POPULATION

Canine thoracic limbs (n=15 limb pairs).

METHODS

Limbs acquired from healthy Labrador Retrievers euthanatized for reasons unrelated to this study were mounted in a limb press and aligned in a standing position followed by axial loading at 30% body weight. Frontal plane radiography was performed in standing and recumbent positions pre- and post-SHO. In the standing position, lateralization of the foot was measured pre- and post-SHO using a textured grid secured to the limb press base plate. Twelve thoracic limb alignment values (mean ± SD and 95% CI) were determined using the center of rotation of angulation (CORA) method were compared using linear mixed models to determine if significant differences existed between limb alignment values pre- or post-SHO, controlling for dog, limb, and limb position.

RESULTS

Six of 12 standing or recumbent alignment values were significantly different pre- and post-SHO. SHO resulted in decreased mechanical lateral distal humeral angle and movement of the mechanical humeral radio-ulnar angle, radio-ulnar metacarpal angle, thoracic humeral angle, and elbow mechanical axis deviation toward coaxial limb alignment. In the standing position, the foot underwent significant lateralization post-SHO.

CONCLUSION

SHO resulted in significant alteration in frontal plane thoracic limb alignment. Additional studies are necessary to determine if the changes reported using our ex vivo model occur following SHO in vivo.