Cadaveric biomechanical study using 6-degree-of-freedom sensors in 8 shoulders. Quantifies how the rotator interval capsule governs glenohumeral range of motion, obligate humeral head translation, and resistance to instability. Tested under three conditions: intact, sectioned, and imbricated.
The rotator interval capsule was anatomically described before this paper, but its functional role in glenohumeral kinematics had never been quantified. Surgeons lacked data on what motion they were trading for stability — or vice versa. When they modified this structure.
When a patient has a positive sulcus sign or posterior instability, rotator interval plication is a targeted adjunct. This paper shows it reduces inferior translation by 7.7 mm and posterior drawer by 7.3–8.3 mm. But budget for roughly 18° of lost extension and up to 38° of lost external rotation.
For the stiff shoulder (adhesive capsulitis, post-cuff repair tightness), releasing the rotator interval decompresses the motion planes that are actually restricted. It also reduces the obligate anterosuperior translation that can load a cuff repair on every flexion arc.
One nuance worth knowing: plication does not affect anterior laxity. If the instability is anterior, the rotator interval is the wrong target.
Cadaveric biomechanical study using 6-degree-of-freedom sensors in 8 shoulders. Quantifies how the rotator interval capsule governs glenohumeral range of motion, obligate humeral head translation, and resistance to instability. Tested under three conditions: intact, sectioned, and imbricated.
The rotator interval capsule was anatomically described before this paper, but its functional role in glenohumeral kinematics had never been quantified. Surgeons lacked data on what motion they were trading for stability — or vice versa. When they modified this structure.
When a patient has a positive sulcus sign or posterior instability, rotator interval plication is a targeted adjunct. This paper shows it reduces inferior translation by 7.7 mm and posterior drawer by 7.3–8.3 mm. But budget for roughly 18° of lost extension and up to 38° of lost external rotation.
For the stiff shoulder (adhesive capsulitis, post-cuff repair tightness), releasing the rotator interval decompresses the motion planes that are actually restricted. It also reduces the obligate anterosuperior translation that can load a cuff repair on every flexion arc.
One nuance worth knowing: plication does not affect anterior laxity. If the instability is anterior, the rotator interval is the wrong target.