Anterolateral Acromioplasty Does Not Change the Critical Shoulder Angle and Acromion Index in a Clinically Relevant Amount

Impact of critical shoulder angle in shoulder pathology: a current concepts review

Background

This review aims to describe the origin and development of critical shoulder angle (CSA) and its correlation with different shoulder pathologies. Current literature is inconclusive in characterizing the role of CSA in predicting pathology and surgical outcomes.

Methods

A literature search of both historical and more contemporary research articles on CSA was conducted to compare data points on the impact of CSA on shoulder pathology and postoperative clinical outcomes. This compilation of studies ranges from retrospective reviews to case series as well as cadaveric imaging studies.

Results

The CSA is a reliable radiographic measure in predicting shoulder pathology in correctly oriented radiographs. Surgically modifying the CSA with arthroscopic lateral acromioplasty and results has largely shown improved recovery of strength postoperatively as with no increase in postsurgical complication rates. However, it remains unclear whether surgical alteration of CSA has a role in preventing clinical failure after arthroscopic procedures such as acromioplasty and rotator cuff repair as well as following shoulder arthroplasty.

Discussion

Stronger conclusions regarding the prognostic utility of CSA are limited by the fact that most studies evaluating CSA are smaller retrospective cohorts. Moving forward, randomized controlled trials being conducted may offer greater insight as to how CSA can improve patient-reported outcomes postoperatively.

Critical Shoulder Angle in Patients With Cuff Tears

OBJECTIVE

The pathogenesis of rotator cuff tears (RCTs) is multifactorial. Critical shoulder angle (CSA), which represents the lateral extension of the acromion over the cuff, has been proposed as an extrinsic risk factor. The aim of the present systematic review and meta-analysis was to analyze the available literature regarding the correlation between RCT and CSA.

METHODS

A review was carried out in accordance with the "Preferred Reporting Items for Systematic reviews and Meta-Analyses" guidelines on July 17, 2023, using the following databases: PubMed, Ovid, and Cochrane Reviews. The following keywords were used: "critical shoulder angle," "rotator cuff tears," and "rotator cuff lesions." The methodological quality of the studies was assessed with the MINORS SCORE.

RESULTS

Twenty-eight studies were included. The average CSA among the 2110 patients with full-thickness RCT was 36.7 degrees, whereas the same value among the 2972 controls was 33.1 degrees. The average CSA in the 348 patients with partial-thickness RCT was 34.6 degrees, whereas it was 38.1 degrees in the 132 patients with massive RCT. The average MINORS score was 15.6.

CONCLUSIONS

CSA values were significantly higher in patients with RCT compared with the asymptomatic population. In addition, it appears that CSA values increase with the severity of rotator cuff involvement.

Editorial Commentary: Classic Arthroscopic Anterolateral Acromioplasty Does Not Translate to Clinically Meaningful Differences in Lateral Acromial Overcoverage

Despite its time-honored tradition, the classic Neer acromioplasty has come under increased scrutiny in the recent literature, particularly when performed in the absence of rotator cuff repair. The American Medical Association Current Procedural Terminology Committee has transitioned the acromioplasty procedure, and definition of the related Current Procedural Terminology code 29827, to a procedure that is "added-on" to shoulder arthroscopy. Several authors have sought to investigate the true value of arthroscopic subacromial decompression for extrinsic sources of impingement. Common indications for acromioplasty include bursal-sided tears, prominent type III hooked acromial morphology, calcified coracoacromial ligament, and severe rotator cuff tendinopathy. However, the classic arthroscopic acromioplasty may not meaningfully address lateral outlet impingement and acromial overcoverage, as measured by an elevated critical shoulder angle or acromial index, thereby leading to persistent abduction impingement and mechanical abrasion. In these cases, lateral acromial resection of up 5 to 10 mm may be preferentially considered to decrease the pathologic critical shoulder angle (>35°) and reduce the risk of primary or secondary rotator cuff tendon failure.