Qualitative and Quantitative Anatomic Descriptions of the Coracoclavicular and Acromioclavicular Ligaments: A Systematic Review

PURPOSE: To summarize the quantitative and qualitative anatomy of the acromioclavicular (AC) and coracoclavicular (CC) ligaments of the AC joint. METHODS: A systematic review of the literature evaluating the quantitative and qualitative anatomy of the CC and AC ligaments of the AC joint was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. RESULTS: The conoid ligament (CL) arises from the posterior coracoid precipice and courses with a tapered inferior apex to insert on the conoid tubercle of the posteroinferior clavicle. The trapezoid ligament originates from the anterior–superior coracoid with medially extending fibers anterior to the conoid’s C-shaped footprint and runs with the CL to insert along the trapezoid line on the inferior aspect of the anterior clavicle, anterolateral to the conoid tubercle. The AC capsule’s superoposterior bundle and the CL are robust stabilizing ligaments characterized by prominent attachment sites to the posteroinferior clavicle. CONCLUSIONS: Clear and consistent quantitative and qualitative descriptions of the CC ligaments (CL and trapezoid ligament) have been well defined; however, quantitative data on the capsuloligamentous anatomy of AC ligaments (superoposterior and anteroinferior) ligaments) remain limited. CLINICAL RELEVANCE: There are high complication and failure rates after AC joint stabilization. To improve patient outcomes, the anatomy of the CC and AC joints needs to be better understood.