This cadaver study used a materials testing machine to measure the force needed to anteriorly sublux the shoulder under different conditions. It quantified how much each rotator cuff tendon and each capsular zone contributes to anterior stability. Shoulders were tested in both neutral and external humeral rotation.
The key mental model here is that a ligament's stabilizing role depends on where it sits relative to the joint, and rotation moves it. When you place a patient in abduction and external rotation (the apprehension position), you are specifically loading the IGHL as it wraps across the anterior joint. This is why the anteroinferior labrum and IGHL complex is the classic site of a Bankart lesion.
In neutral rotation the SGHL and MGHL share the load, so anterior stability is more distributed. This explains why the arm position at the time of injury shapes which structures fail. The circle concept is the practical takeaway: dislocation requires failure of structures on both sides of the joint, not just the anterior capsule.
The finding that no single cuff tendon dominates reframes the subscapularis, which was historically emphasized, as one of several equal dynamic compressors rather than the lone key stabilizer.
This cadaver study used a materials testing machine to measure the force needed to anteriorly sublux the shoulder under different conditions. It quantified how much each rotator cuff tendon and each capsular zone contributes to anterior stability. Shoulders were tested in both neutral and external humeral rotation.
The key mental model here is that a ligament's stabilizing role depends on where it sits relative to the joint, and rotation moves it. When you place a patient in abduction and external rotation (the apprehension position), you are specifically loading the IGHL as it wraps across the anterior joint. This is why the anteroinferior labrum and IGHL complex is the classic site of a Bankart lesion.
In neutral rotation the SGHL and MGHL share the load, so anterior stability is more distributed. This explains why the arm position at the time of injury shapes which structures fail. The circle concept is the practical takeaway: dislocation requires failure of structures on both sides of the joint, not just the anterior capsule.
The finding that no single cuff tendon dominates reframes the subscapularis, which was historically emphasized, as one of several equal dynamic compressors rather than the lone key stabilizer.