This cadaver study measured the coracoacromial arch as a defined anatomic space in 140 shoulders. It asked whether the size of that space, and its fit with the humeral head, differs between shoulders with and without full-thickness rotator cuff tears. Computer modeling quantified the supraspinatus outlet area for each group.
When you see a hooked or anteriorly projecting acromion on a patient with cuff symptoms, this paper gives you the anatomic reasoning behind decompression. The key mental model is a size mismatch: the supraspinatus outlet is the arch area minus the humeral head footprint, and tear shoulders lose 22.5% of that space. No single measurement predicts a tear, but the cumulative geometry does.
This is why anterior acromioplasty targets the anteroinferior acromion. The paper supports resecting only 3 to 4 mm to reduce overhang while sparing deltoid origin, since radical acromionectomy causes serious deltoid dysfunction.
The findings are compatible with both impingement theories: extrinsic compression from a tight arch, and intrinsic tearing that lets the head migrate superiorly into the arch. A narrow outlet worsens both. Remember the limits: this is a static cadaver model with the head centered, so it represents a best case; dynamic superior translation narrows the space further.
This cadaver study measured the coracoacromial arch as a defined anatomic space in 140 shoulders. It asked whether the size of that space, and its fit with the humeral head, differs between shoulders with and without full-thickness rotator cuff tears. Computer modeling quantified the supraspinatus outlet area for each group.
When you see a hooked or anteriorly projecting acromion on a patient with cuff symptoms, this paper gives you the anatomic reasoning behind decompression. The key mental model is a size mismatch: the supraspinatus outlet is the arch area minus the humeral head footprint, and tear shoulders lose 22.5% of that space. No single measurement predicts a tear, but the cumulative geometry does.
This is why anterior acromioplasty targets the anteroinferior acromion. The paper supports resecting only 3 to 4 mm to reduce overhang while sparing deltoid origin, since radical acromionectomy causes serious deltoid dysfunction.
The findings are compatible with both impingement theories: extrinsic compression from a tight arch, and intrinsic tearing that lets the head migrate superiorly into the arch. A narrow outlet worsens both. Remember the limits: this is a static cadaver model with the head centered, so it represents a best case; dynamic superior translation narrows the space further.