Anatomical study of the position and orientation of the coracoclavicular ligaments: Differences in bone tunnel position by gender.

BACKGROUND: Reconstructing both coracoclavicular ligaments following acromioclavicular dislocation has recently been reported to restore the function of the acromioclavicular joint better than traditional procedures. Knowing the appropriate position and orientation of the bone tunnels and the potential risks of neurovascular injuries leads to safe reconstruction. We aimed to answer the following questions: what is the difference in the accurate clavicular bone tunnel positions (BTPs) during coracoclavicular ligament reconstruction between sex, and what are the potential risks for neurovascular injuries?

HYPOTHESIS: The BTPs differ by sex at the site of coracoclavicular ligament reconstruction.

PATIENTS AND METHODS: We introduced two Kirschner wires into 25 cadaver shoulders (17 male, 8 female), one through the insertion center of the trapezoid ligament and one through the conoid ligament, and measured the distance from the respective Kirschner wire insertion points to the bony landmarks of the clavicle and the oblique angle of each Kirschner wire. The shortest distance from the insertion point of each Kirschner wire to the suprascapular nerve and artery was also measured.

RESULTS: While the distance from the acromioclavicular joint to the respective Kirschner wire insertion points tended to be longer in males, the ratio of these insertion points to total clavicle length was constant. Other measurements for respective Kirschner wire insertions to the bony landmarks and neurovascular structures were comparable, as were abduction and retroversion angles. The distance from the suprascapular nerve to the insertion point of the conoid ligament at the coracoid process was 13.8±4.0mm, while the distance from the suprascapular artery was 7.1±3.3mm.

DISCUSSION: Appropriate position and orientation of the bone tunnels, and the ratio of the BTPs to the total clavicular length, aid surgeons in performing the reconstruction. The conoid ligament insertion on the coracoid was just proximal to the suprascapular artery, so surgeons should be careful with conoid insertion.

LEVEL OF EVIDENCE: V, cadaver study.