Abstract
Background
Several recent techniques for acromioclavicular and coracoclavicular ligament reconstruction use coracoid drill holes that may increase coracoid fracture risk. We investigated how the size and location of drill holes in the coracoid increase the risk of fracture.
Methods
An initial pilot study used Sawbones® scapula models (Pacific Research Labs, Vashon, WA, USA) with coracoids at four sites having either 4-mm or 6-mm drills and loaded to failure. Then, six matched pairs of cadaveric coracoids were drilled with 6-mm holes at the true coracoid base or just lateral to the coracoclavicular ligament attachment and also loaded to failure.
Results
In the Sawbones® models, 6-mm holes weakened the coracoids more than 4-mm holes (35% versus 13%). In the cadavers, 6-mm drill holes drilled at the true coracoid base were approximately 60% stronger (p < 0.01) than the coracoids with 6-mm holes drilled lateral to the coracoclavular ligaments.
Discussion
The risk of coracoid fracture appears to be decreased with smaller drill holes and with holes placed at the coracoid base. We recommend using drill guides that target the base of the coracoid. Correct placement of drill holes for ligament reconstruction is important to prevent subsequent coracoid fracture.
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