Evaluation of the optimal plate position for the fixation of supraglenoid tubercle fractures in warmbloods.

This study aims to understand the optimal placement for fixing supraglenoid tubercle fractures in horses, having investigated the thickness of the scapular cortex, the bone density in the lower part of the scapula, and the course of the suprascapular nerve.

Methods

• The researchers used 12 horse cadaveric shoulders for this study. These shoulders were examined using computed tomography (CT).
• They recorded the thickness and density of the scapula using CT scans. The density measurements were recorded in Hounsfield units (HU), a standard unit in CT imaging.
• The morphometry and morphology of the suprascapular nerve course were determined through careful dissection of each shoulder.
• Statistical comparisons were made between the data obtained from the front (cranial) and back (caudal) parts of the scapula.

Results

• The suprascapular nerve was found on the outer bone layer (periosteum) and within connective tissue at the front side of the scapula. The nerve divided (ramified) into the supraspinatus muscle, a canonically known muscle of the horse’s shoulder area.
• It also ran towards the back and outer side just below the scapular spine, a prominent bone ridge of the scapula.
• The CT density measurements showed that the thickness of the front side of the scapula was significantly larger than that at the back.
• In contrast, the bone density of the lower part of the scapula towards the back was significantly higher than that at the front.

Conclusions

• The detailed knowledge of these anatomical elements is crucial for a surgical approach to the supraglenoid tubercle, an elevation of bone in the scapula.
• Avoiding the suprascapular nerve is easiest at the front most part of the scapula, where the nerve has not yet divided.
• The density and thickness of the scapular cortex significantly influence the stability of the fixation.