This cadaveric biomechanical study tested which capsular structures restrain anterior-posterior translation of the shoulder in 90° of abduction. Using selective sectioning of ligaments in 23 fresh-frozen shoulders, it quantified the role of the inferior glenohumeral ligament complex and its anterior and posterior bands. It asks what actually holds the shoulder stable in the position where most clinical instability occurs.
When you see a shoulder that dislocates in abduction and external rotation, the structure that failed is the inferior glenohumeral ligament complex, not the superior or middle ligaments. This study grounds that clinical intuition in quantitative data: cutting the IGHLC made shoulders frankly unstable, while cutting the SGHL and MGHL changed nothing in the abducted position.
The reciprocal band behavior gives you a mental model. Extension and neutral load the anterior band, flexion loads the posterior band, so the position of apprehension points you toward the deficient structure.
The circle concept is the practical takeaway. Because dislocation requires damage on both sides of the capsule, a durable repair must restore the whole IGHLC: an anterior anchor, a posterior anchor, and a competent axillary pouch in between. This is also why posterior stabilization fails when it relies on the thin, collagen-poor posterosuperior capsule instead of advancing IGHLC tissue inferiorly.
This cadaveric biomechanical study tested which capsular structures restrain anterior-posterior translation of the shoulder in 90° of abduction. Using selective sectioning of ligaments in 23 fresh-frozen shoulders, it quantified the role of the inferior glenohumeral ligament complex and its anterior and posterior bands. It asks what actually holds the shoulder stable in the position where most clinical instability occurs.
When you see a shoulder that dislocates in abduction and external rotation, the structure that failed is the inferior glenohumeral ligament complex, not the superior or middle ligaments. This study grounds that clinical intuition in quantitative data: cutting the IGHLC made shoulders frankly unstable, while cutting the SGHL and MGHL changed nothing in the abducted position.
The reciprocal band behavior gives you a mental model. Extension and neutral load the anterior band, flexion loads the posterior band, so the position of apprehension points you toward the deficient structure.
The circle concept is the practical takeaway. Because dislocation requires damage on both sides of the capsule, a durable repair must restore the whole IGHLC: an anterior anchor, a posterior anchor, and a competent axillary pouch in between. This is also why posterior stabilization fails when it relies on the thin, collagen-poor posterosuperior capsule instead of advancing IGHLC tissue inferiorly.