# Are Rotator Cuff Tears in Anterior Shoulder Dislocation Associated With a High Critical Shoulder Angle? A Retrospective Analysis

## TL;DR

This study examines if the critical shoulder angle can predict rotator cuff tears after shoulder dislocation and finds no significant link, but notes age is a factor.

## Contribution

The study evaluates the reliability of critical shoulder angle as a screening tool for rotator cuff tears in shoulder dislocation patients.

## Key findings

- No significant difference in critical shoulder angle between patients with and without rotator cuff tears.
- Older age was significantly associated with a higher likelihood of sustaining a rotator cuff tear.
- Intra-observer reliability of CSA measurements was excellent, while inter-observer reliability was good.

## Abstract

Aims

This study aims to investigate whether the critical shoulder angle (CSA) could serve as an effective screening tool to predict acute rotator cuff tears in patients with first-time anterior glenohumeral dislocation and to assess the inter- and intra-observer reliability of CSA measurements in this cohort.

Methods

A review of all patients with a first-time anterior shoulder dislocation was carried out over a 17-month period at Manchester NHS Foundation Trust, across the Wythenshawe Hospital and Manchester Royal Infirmary sites. Three shoulder surgeons independently measured CSA on post-reduction radiographs, and all patients underwent imaging to assess for a traumatic rotator cuff tear (RCT). Statistical analysis was performed using unpaired t-tests and subgroup analysis based on age and rotator cuff tear presence. Inter- and intra-observer reliability was assessed using Cronbach's alpha.

Results

Sixty-five patients (36 female, 29 male) met the inclusion criteria. Forty-two patients (65%) had a rotator cuff tear detected on further imaging. The mean CSA for the tear group was 38.14° (SD 4.6), and for the non-tear group, it was 37.45° (SD 4.6), with no significant difference (p = 0.5598). Age was significantly higher in the tear group (64.5 years) compared to the non-tear group (58.1 years, p = 0.0225), with a positive correlation between age and the likelihood of sustaining a rotator cuff tear. Inter-observer reliability was found to be "good" (Cronbach’s alpha = 0.8519), while intra-observer reliability was "excellent" (Cronbach’s alpha ≥ 0.9282).

Conclusion

This study found no significant association between CSA and the incidence of rotator cuff tears following a traumatic anterior shoulder dislocation. However, increasing age was associated with a higher likelihood of sustaining a rotator cuff tear following anterior shoulder dislocation. This study has demonstrated that intra- and inter-observer reliability were excellent and good, respectively. These findings suggest that CSA may not be a reliable screening tool for rotator cuff tears following shoulder dislocation. Larger, standardised studies are needed to further explore this relationship.