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Cohort studyJSES reviews, reports, and techniques · 2026

Critical shoulder angle: a "combined shoulder angle"-balanced contributions of glenoid inclination and acromial angle in shoulder arthritis progression.

Marc-Olivier Gauci, Hoel Letissier, Christophe Andro … Antoine de Chanterac

RheumatologyCohort study

Primary glenohumeral osteoarthritis is associated with a lower Critical Shoulder Angle.

Critical shoulder angle: a "combined shoulder angle"-balanced contributions of glenoid inclination and acromial angle in shoulder arthritis progression.

Marc-Olivier Gauci … Antoine de Chanterac

JSES reviews, reports, and techniques · 2026

Background

The critical shoulder angle (critical shoulder angle) has been described as a morphometric value that could be predisposing to the evolution of a shoulder toward a primary glenohumeral osteoarthritis (primary glenohumeral osteoarthritis) or massive rotator cuff tear (massive rotator cuff tear).

Purpose

The aim of this study is to evaluate the impact of glenoid inclination and acromial angle measurements on critical shoulder angle value in primary glenohumeral osteoarthritis and massive rotator cuff tear.

Methods

Computed tomography scans of 186 patients were extracted from our database and assigned into 3 groups: control group (48 healthy shoulders) and 2 pathological shoulder groups with no glenoid erosion: 66 massive rotator cuff tear (E0 glenoids) and 72 primary glenohumeral osteoarthritis (A1 or B1 glenoids).

n = 186 patients

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Results

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± 4°

a lower shoulder angle measured in people with shoulder arthritis

n = 186 patients

More results

There was a significant difference between the massive rotator cuff tear and primary glenohumeral osteoarthritis for glenoid inclination (8 ± 5° and 6 ± 6°, respectively, P = .026) and no difference with the control group (7 ± 5°, P > .05).

More results

The acromial angle was not statistically different among the 3 groups (25 ± 6°, 23 ± 6°, and 24 ± 6, respectively, P = .063).

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Conclusion · 1 of 3

Critical shoulder angle is a reliable parameter for predicting progression to primary glenohumeral osteoarthritis or massive rotator cuff tear, with a notable effect size.

Conclusion · 2 of 3

No single component of critical shoulder angle predominates, and the linear correlation between glenoid inclination and acromial angle underscores a balance between these angles.

Conclusion · 3 of 3

Thus, critical shoulder angle should indeed be considered as a "combined shoulder angle."

Post

Critical shoulder angle: a "combined shoulder angle"-balanced contributions of glenoid inclination and acromial angle in shoulder arthritis progression.

Primary glenohumeral osteoarthritis is associated with a lower Critical Shoulder Angle.

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