Cadaveric biomechanical study of 12 shoulders using sequential ligament sectioning and load-displacement testing. Quantifies the individual contributions of the AC, conoid, and trapezoid ligaments across 12 modes of joint displacement. Addresses which ligament controls stability — and under what conditions.
Two ligaments, two jobs — and understanding which does what changes how you interpret AC joint injuries. The AC ligament controls horizontal (posterior) stability across all load levels. The conoid ligament controls superior and anterior stability under high loads. The loads seen in trauma.
When a patient has a Rockwood III or higher injury (complete coracoclavicular disruption), they have lost the primary restraint to superior translation under load. That is the biomechanical basis for why grades III–V are unstable in a clinically meaningful way, and why conoid reconstruction is central to modern anatomic AC joint repair.
The authors also flag that distal clavicle excision may prevent ligament participation in healing. A caution worth carrying into conversations about Mumford procedures after AC joint trauma.
Cadaveric biomechanical study of 12 shoulders using sequential ligament sectioning and load-displacement testing. Quantifies the individual contributions of the AC, conoid, and trapezoid ligaments across 12 modes of joint displacement. Addresses which ligament controls stability — and under what conditions.
Two ligaments, two jobs — and understanding which does what changes how you interpret AC joint injuries. The AC ligament controls horizontal (posterior) stability across all load levels. The conoid ligament controls superior and anterior stability under high loads. The loads seen in trauma.
When a patient has a Rockwood III or higher injury (complete coracoclavicular disruption), they have lost the primary restraint to superior translation under load. That is the biomechanical basis for why grades III–V are unstable in a clinically meaningful way, and why conoid reconstruction is central to modern anatomic AC joint repair.
The authors also flag that distal clavicle excision may prevent ligament participation in healing. A caution worth carrying into conversations about Mumford procedures after AC joint trauma.