Relationship Between the Critical Shoulder Angle and Shoulder Disease

Abstract

» In this review, we describe the history of the Critical Shoulder Angle (CSA), the utility of the CSA in identifying rotator cuff tears and glenohumeral osteoarthritis, and the association between the CSA and patient-reported outcomes. Additionally, we address some of the controversies surrounding the CSA with an updated literature review. » The CSA is the angle between the plane of the glenoid fossa (the line from the inferior edge of the glenoid to the superior edge of the glenoid) and a line drawn from the inferior edge of the glenoid to the lateral edge of the acromion on a true anteroposterior (Grashey) shoulder radiograph. » An increased CSA (.35°) is thought to alter deltoid vectors, which results in increased superior shear forces on the rotator cuff muscles. This increased loading of the rotator cuff may be a risk factor for the development of rotator cuff tears. » A decreased CSA (,30°) is associated with glenohumeral arthritis due to the increased compressive forces across the glenohumeral joint. » Reports in the literature have both supported and refuted the associations between the CSA, shoulder disease, and clinical treatment outcomes. These conflicting findings may be attributable to the lack of standardized radiographic methods for measuring CSA and/or to measurement errors. » Prospective longitudinal cohort studies involving a standard and reproducible method of CSA measurement are needed to elucidate the true relationship between the CSA and shoulder disease. Disclosure: No external funding was used for this study. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked "yes" to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work and "yes" to indicate that the author had other relationships or activities that could be perceived to influence, or have the potential to influence, what was written in this work (http://links.lww.com/JBJSREV/A359).

The effect of critical shoulder angle on functional compensation in the setting of cuff tear arthropathy

“… 12 Watanabe et al 27 noted that patients with RCTs had a larger CSA compared with patients without RCTs ( P < .001). Li et al 14 similarly found that CSAs > 35° were associated with RCTs, due to the increased superior shear forces, whereas CSAs < 30° were associated with glenohumeral osteoarthritis, due to increased compressive forces across the glenohumeral joint. The value of this study is that it is the first to demonstrate the difference in the cuff-deficient shoulder function as it relates to radiographic parameters.…”

Rotator Cuff Tears : Short- and long-term aspects on treatment outcome

“…The most common way is called the Critical Shoulder Angle (CSA), and measures the angle between the glenoid and the most lateral part of the acromion 194 . Larger CSA has been found to be associated with an increased risk of rotator cuff disease in some studies 166,194 , but not all studies have support for this association 25 . There are also other measures of the bony anatomy that may indicate an increased risk of rotator cuff tear, such as the greater tuberosity angle 58 and the Y-, G-and R-angles 233 .…”

Critical shoulder angle (CSA): age and gender distribution in the general population

“…Although in three recent studies [ 20 – 22 ], the correlation of CSA with rotator cuff diseases has been strongly criticized, the popularity of CSA has increased over time. Nonetheless, many points on CSA remain to be elucidated [ 23 ]. In a retrospective analysis of longitudinally collected data, Chalmers et al.…”