Editorial Commentary: Current Indications for Lateral Acromioplasty Include Patients With Elevated Critical Shoulder Angle Plus Subacromial Impingement With Rotator Cuff Pathology or Previous Rotator Cuff Repair

The critical shoulder angle (CSA) reflects the lateral extent of the acromion and the inclination of the glenoid. In 2013, CSA was first introduced and its association with rotator cuff (RC) tears and glenohumeral osteoarthritis (GHOA) was shown. It was speculated that with a high CSA, there was an increased superior force vector from the deltoid and that this superior force led to RC tears. Conversely, when the CSA was low, there was a greater compressive force from the deltoid and that this compressive force led to GHOA. CSA serves as a further development of 2 previously reported measurements (glenoid inclination and acromial index). A key potential therapeutic aspect of the CSA is the ability to modify it surgically, which theoretically could protect RC repairs or prevent progression. In our current clinical practice, we perform lateral acromioplasty (LA) in patients undergoing treatment of subacromial impingement with an "at-risk" rotator cuff (partial rotator cuff tear and severe tendinopathy on magnetic resonance imaging) with a CSA > 38° or all patients with a CSA >35° after an RC repair to protect the RC repair construct. The relationships of high and low CSA, the anatomic safe zone, and thus clinical applicability of LA are well established and performed in our daily surgical practice. However, we do not yet have widespread clear clinical evidence on potential benefits regarding the clinical outcome after LA. Finally, at this time, the downsides seem minimal, so we continue to use LA as an adjunct in patients with RC tears and RC tendons that are at risk.