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

The Critical Shoulder Angle: A Significant Radiological Measure in Rotator Cuff vs. Glenohumeral Osteoarthritis in Chilean Patients-A Descriptive Cross-Sectional Study

Background: Shoulder pain is one of the most important musculoskeletal conditions affecting the upper extremities. Glenohumeral osteoarthritis (GHOA) and rotator cuff injuries (RCIs) are notable for their high prevalence. The critical shoulder angle (CSA) is a significant radiological measure for determining the diagnosis and progression of patients with these conditions. Although there are reports in the international literature about this measure, in our country, guideline values considering these two pathologies are unknown. Objective: Our objective was to assess patients diagnosed with GHOA and RCI using an AP X-ray view and the CSA. Methods: To conduct this, we identified differences between sexes and age categories. Fifty-nine adult patients with GHOA and RCI were included. CSA grades varied depending on the age category and type of injury evaluated. Results: Significant differences between the age ranges of 40 and 54 (p = 0.05), 55-69 (p = 0.001), and 70-84 (p = 0.017) were observed. Conclusions: Patients with RCI tended to be younger and have a higher CSA compared to those with GHOA. It is important to have more normative values and to continue monitoring the critical shoulder angle in these patients.

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.

Is prenatal testosterone-estrogen balance related to critical shoulder angle?

BACKGROUND

The 2D:4D ratio (an indicator of prenatal testosterone-estrogen balance) is the ratio of the second finger length to the fourth finger length. We hypothesized that low 2D:4D values indicating high prenatal testosterone exposure may be associated with increased critical shoulder angle (CSA).

AIMS

The aim of this study was to evaluate the relationship between CSA and 2D:4D ratio.

METHODS

Meeting the study criteria, 252 patients were included in the study. We measured CSA on true anterior-posterior radiographs, glenoid version(GV) and glenoid inclination(GI) on MRI images and the lengths of the second and fourth fingers on both hands of the patients. Additionally, we compared 2D:4D ratios and CSA, GV, GI measurements.

RESULTS

We found a significant negative correlation between CSA and the 2D:4D ratio in both hands (p < 0.001). Patients with CSA > 35° had a significantly lower 2D:4D ratio than patients with CSA < 35° (p < 0.001). When the patients were grouped according to CSA35°, the cut-off value for the left-hand 2D:4D ratio was 0.96, which showed 84.8 % sensitivity and 83.3 % specificity(AUC:0.911). Patients were compared in terms of CSA by categorizing as 2D:4D > 1 and 2D:4D < 1. Accordingly, the CSA value was significantly lower in patients with 2D:4D > 1. In the classification made according to this length classification of the left hand, the cut-off value was 30.25°. This value showed 92.2 % sensitivity and 85 % specificity(AUC:0.956).

CONCLUSION

The 2D:4D ratio is related to CSA. A low 2D:4D ratio(<0.96), indicating high intrauterine testosterone exposure, is associated with CSA > 35°, while a high 2D:4D ratio (>1), indicating low intrauterine testosterone exposure, is associated with a low CSA(<30.25°).

Reliability and accuracy of the critical shoulder angle measured by anteroposterior radiographs: using digitally reconstructed radiograph from 3-dimensional computed tomography images

BACKGROUND

Accuracy of current standard radiographic measurement of the critical shoulder angle (CSA) is not well established. This study analyzed the reliability and accuracy of the CSA measurements obtained via anteroposterior (AP) radiographs, using a digitally reconstructed radiograph (true AP view) generated from a computed tomography image as the gold standard.

METHODS

The CSA was measured on the radiographs and true AP views of 88 consecutive patients who had undergone shoulder arthroscopy for rotator cuff tears. Intraobserver and interobserver reliabilities of the CSA, measured by 2 orthopedic surgeons, were evaluated, and the average deviation of the CSA between radiographs and true AP views was calculated. Moreover, we compared the deviation of CSA between standard AP films (types A1 and C1) and nonstandard AP films (other types) against the Suter-Henninger criteria.

RESULTS

Intraobserver and interobserver reliabilities were almost perfect on radiographs (0.96, 0.86) and true AP views (0.93, 0.85). The average deviation of CSA was 2.1° ± 1.6° for observer 1 and 2.2° ± 1.9° for observer 2. The percentage of cases with deviations of 2° or more when compared with the true AP view was 42% (37 of 88) for observer 1 and 53% (47 of 88) for observer 2. Only 22% (19 of 88) of films were standard AP films. The average deviation of CSA was not significantly different between standard and nonstandard AP films for observer 1 (standard 1.9° ± 1.3°; nonstandard 2.1° ± 1.7°; P = .76) and observer 2 (standard 1.6° ± 1.5°; nonstandard 2.4° ± 1.9°; P = .09).

CONCLUSION

The CSA measurements using radiography were highly congruent, but a large measurement deviation occurred between radiographs and true AP views. The clinical usefulness and role of CSA in diagnosis require careful consideration.