Controversy on the Association of the Critical Shoulder Angle and the Development of Degenerative Rotator Cuff Tears: Is There a True Association? A Meta-analytical Approach

Background: The role of the critical shoulder angle (CSA) as a risk factor for rotator cuff tear (RCT) remains controversial. Studies on the association between the CSA and RCT show considerable differences in design, and this could be responsible for the variation in study results. Purpose: To (1) describe the reliability of CSA measurement and (2) evaluate the results of the studies reporting the association between the CSA and RCT using meta-analytical techniques to explore potential sources of variation of study results. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: MEDLINE, EMBASE, and CINAHL electronic databases were searched through June 30, 2019. Case-control and cross-sectional studies reporting the association of the CSA and RCT were selected. The weighted mean difference in the CSA was estimated using a random-effects model. Prediction interval was computed to better express uncertainties in the effect estimate. Metaregression and subgroup analyses were performed to explore potential sources of heterogeneity. Results: A total of 14 studies, including 1154 cases and 1271 controls, were identified. Of these studies, 79% (11/14) assessed the reliability of the CSA measurement, demonstrating an excellent intraobserver (range, 0.91-0.99) and interobserver (range, 0.87-0.99) reliability. Compared with controls, cases with RCT showed larger measurements of the CSA (3.3° [95% CI, 2.3°- 4.4°]). However, there was a high heterogeneity ( I2 = 93%), and the 95% prediction interval (-0.4° to 7.1°) included no difference in the CSA. Results of the metaregression analysis showed a significant association of several methodological aspects with the heterogeneity. The difference in the CSA tended to be larger when only full-thickness tears were included, when no specific defined criterion for assessing radiographic viewing perspective was used, in studies with smaller sample sizes, and in studies at higher risk of bias. Conclusion: While the CSA can be reliably measured, the difference in the CSA between cases and controls varied from very large to modest or almost no difference. Several determinants of heterogeneity were determined. Owing to this heterogeneity, it is difficult to gain an insight into the strength and exact nature of the association between the CSA and RCT with the current evidence.

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Neither critical shoulder angle nor acromion index were related with specific pathology 20 years later!

Knee Surgery Sports Traumatology Arthroscopy ◽

10.1007/s00167-021-06602-y ◽

2021 ◽

Author(s):

Hanna C. Björnsson Hallgren ◽

Lars Adolfsson

Keyword(s):

Rotator Cuff ◽

Elective Surgery ◽

Rotator Cuff Tears ◽

Level Of Evidence ◽

Critical Shoulder Angle ◽

Glenohumeral Osteoarthritis ◽

The Difference ◽

Acromion Index ◽

Shoulder Angle

Abstract Purpose The critical shoulder angle (CSA) and the acromion index (AI) are measurements of acromial shape reported as predictors of degenerative rotator cuff tears (RCT) and glenohumeral osteoarthritis (GH OA). Whether they are the cause or effect of shoulder pathologies is uncertain since pre-morbid radiographs most often are lacking. The main aim of this study was to investigate if CSA or AI were related to the development of RCT or GH OA after 20 years. A secondary aim was to investigate if the CSA and AI had changed over time. Methods In the hospital archive, 273 preoperative plain shoulder radiographs were found of patients scheduled for elective surgery other than cuff repair and arthroplasty. Forty-five images fulfilled the strict criteria published by Suter and Henninger (2015) and were used to measure CSA and AI with two independent assessors. No patient had any sign of OA in the index radiographs or any information in the medical records indicating RCT. After a median of 20 (16–22) years, 30 of these patients were radiologically re-examined with bilateral true frontal views and ultrasound of the rotator cuff. There were 19 men (20 study shoulders) and 11 females (12 study shoulders). Results Mean age at follow-up was 56 (32–78) years. There was no correlation between CSA (r = 0.02) (n.s) or AI (r = − 0.13) (n.s) in the primary radiographs and OA at follow-up. Nor was any correlation found between index CSA (r = 0.12) (n.s) or AI (r = − 0.13) (n.s) and RCT at follow-up. Mean difference in CSA was − 1.7 (− 10–3) degrees and mean AI difference was − 0.04 (− 0.13–0.09) between the first and the second radiographs, 20 years later. Bilaterally, mean CSA was 32 and AI 0.61 at follow-up. Conclusion In this study, no correlation between the CSA, AI and development of OA or RCT could be found. The mean CSA and AI decreased over a 20-year period but the difference was very small. No difference was found between the study shoulders and the contralaterals. These findings question previously reported etiological associations between scapular anatomy and the development of OA or RCT and thereby the use of these calculations as the basis of treatment. Level of evidence III.

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Critical shoulder angle does not influence retear rate after arthroscopic rotator cuff repair

Knee Surgery Sports Traumatology Arthroscopy ◽

10.1007/s00167-021-06652-2 ◽

2021 ◽

Author(s):

C. J. Como ◽

J. D. Hughes ◽

B. P. Lesniak ◽

A. Lin

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Repair ◽

Arthroscopic Rotator Cuff Repair ◽

Critical Shoulder Angle ◽

Arthroscopic Rotator Cuff ◽

Cuff Repair ◽

Retear Rate ◽

Shoulder Angle

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Critical shoulder angle is associated with full-thickness rotator cuff tears in patients with glenohumeral osteoarthritis

Journal of Shoulder and Elbow Surgery ◽

10.1016/j.jse.2017.05.020 ◽

2017 ◽

Vol 26 (12) ◽

pp. e376-e381 ◽

Cited By ~ 22

Author(s):

Matthew T. Mantell ◽

Ryan Nelson ◽

Jeremiah T. Lowe ◽

Donald P. Endrizzi ◽

Andrew Jawa

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Tears ◽

Full Thickness ◽

Critical Shoulder Angle ◽

Glenohumeral Osteoarthritis ◽

Shoulder Angle

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Relationship Between Deltoid and Rotator Cuff Muscles During Dynamic Shoulder Abduction: A Biomechanical Study of Rotator Cuff Tear Progression

The American Journal of Sports Medicine ◽

10.1177/0363546518768276 ◽

2018 ◽

Vol 46 (8) ◽

pp. 1919-1926 ◽

Cited By ~ 13

Author(s):

Felix Dyrna ◽

Neil S. Kumar ◽

Elifho Obopilwe ◽

Bastian Scheiderer ◽

Brendan Comer ◽

...

Keyword(s):

Rotator Cuff ◽

Dynamic Testing ◽

Correlation Coefficients ◽

Biomechanical Study ◽

Rotator Cuff Tears ◽

Shoulder Abduction ◽

Mean Values ◽

Critical Shoulder Angle ◽

Anterior Deltoid ◽

Shoulder Angle

Background: Previous biomechanical studies regarding deltoid function during glenohumeral abduction have primarily used static testing protocols. Hypotheses: (1) Deltoid forces required for scapular plane abduction increase as simulated rotator cuff tears become larger, and (2) maximal abduction decreases despite increased deltoid forces. Study Design: Controlled laboratory study. Methods: Twelve fresh-frozen cadaveric shoulders with a mean age of 67 years (range, 64-74 years) were used. The supraspinatus and anterior, middle, and posterior deltoid tendons were attached to individual shoulder simulator actuators. Deltoid forces and maximum abduction were recorded for the following tear patterns: intact, isolated subscapularis (SSC), isolated supraspinatus (SSP), anterosuperior (SSP + SSC), posterosuperior (infraspinatus [ISP] + SSP), and massive (SSC + SSP + ISP). Optical triads tracked 3-dimensional motion during dynamic testing. Fluoroscopy and computed tomography were used to measure critical shoulder angle, acromial index, and superior humeral head migration with massive tears. Mean values for maximum glenohumeral abduction and deltoid forces were determined. Linear mixed-effects regression examined changes in motion and forces over time. Pearson product-moment correlation coefficients ( r) among deltoid forces, critical shoulder angles, and acromial indices were calculated. Results: Shoulders with an intact cuff required 193.8 N (95% CI, 125.5 to 262.1) total deltoid force to achieve 79.8° (95% CI, 66.4° to 93.2°) of maximum glenohumeral abduction. Compared with native shoulders, abduction decreased after simulated SSP (–27.2%; 95% CI, –43.3% to –11.1%, P = .04), anterosuperior (–51.5%; 95% CI, –70.2% to –32.8%, P < .01), and massive (–48.4%; 95% CI, –65.2% to –31.5%, P < .01) cuff tears. Increased total deltoid forces were required for simulated anterosuperior (+108.1%; 95% CI, 68.7% to 147.5%, P < .01) and massive (+57.2%; 95% CI, 19.6% to 94.7%, P = .05) cuff tears. Anterior deltoid forces were significantly greater in anterosuperior ( P < .01) and massive ( P = .03) tears. Middle deltoid forces were greater with anterosuperior tears ( P = .03). Posterior deltoid forces were greater with anterosuperior ( P = .02) and posterosuperior ( P = .04) tears. Anterior deltoid force was negatively correlated ( r = −0.89, P = .01) with critical shoulder angle (34.3°; 95% CI, 32.0° to 36.6°). Deltoid forces had no statistical correlation with acromial index (0.55; 95% CI, 0.48 to 0.61). Superior migration was 8.3 mm (95% CI, 5.5 to 11.1 mm) during testing of massive rotator cuff tears. Conclusion: Shoulders with rotator cuff tears require considerable compensatory deltoid function to prevent abduction motion loss. Anterosuperior tears resulted in the largest motion loss despite the greatest increase in deltoid force. Clinical Relevance: Rotator cuff tears place more strain on the deltoid to prevent abduction motion loss. Fatigue or injury to the deltoid may result in a precipitous decline in abduction, regardless of tear size.

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Risk Factors, Pathobiomechanics and Physical Examination of Rotator Cuff Tears

The Open Orthopaedics Journal ◽

10.2174/1874325001610010277 ◽

2016 ◽

Vol 10 (1) ◽

pp. 277-285 ◽

Cited By ~ 6

Author(s):

Samuel G. Moulton ◽

Joshua A. Greenspoon ◽

Peter J. Millett ◽

Maximilian Petri

Keyword(s):

Risk Factors ◽

Rotator Cuff ◽

Physical Examination ◽

Diagnostic Accuracy ◽

Literature Search ◽

Glenohumeral Joint ◽

Rotator Cuff Tears ◽

Critical Shoulder Angle ◽

Common Risk Factors ◽

Shoulder Angle

Background: It is important to appreciate the risk factors for the development of rotator cuff tears and specific physical examination maneuvers. Methods: A selective literature search was performed. Results: Numerous well-designed studies have demonstrated that common risk factors include age, occupation, and anatomic considerations such as the critical shoulder angle. Recently, research has also reported a genetic component as well. The rotator cuff axially compresses the humeral head in the glenohumeral joint and provides rotational motion and abduction. Forces are grouped into coronal and axial force couples. Rotator cuff tears are thought to occur when the force couples become imbalanced. Conclusion: Physical examination is essential to determining whether a patient has an anterosuperior or posterosuperior tear. Diagnostic accuracy increases when combining a series of examination maneuvers.

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Radiographic shoulder parameters and their relationship to outcomes following rotator cuff repair: a systematic review

Shoulder & Elbow ◽

10.1177/1758573219895987 ◽

2020 ◽

pp. 175857321989598

Author(s):

Musa B Zaid ◽

Nathan M Young ◽

Valentina Pedoia ◽

Brian T Feeley ◽

C Benjamin Ma ◽

...

Keyword(s):

Systematic Review ◽

Rotator Cuff ◽

Rotator Cuff Repair ◽

Patient Reported Outcomes ◽

Critical Shoulder Angle ◽

Patient Reported ◽

Acromion Index ◽

Bony Morphology ◽

Cuff Repair ◽

Shoulder Angle

Background Anatomic parameters, such as the critical shoulder angle and acromion index, have emerged as methods to quantify scapular anatomy and may contribute to rotator cuff pathology. The purpose of this paper is to investigate the published literature on influences of scapular morphology on the development of re-tears and patient-reported outcomes following rotator cuff repair. Methods A systematic review of the Embase and PubMed databases was performed to identify published studies on the potential influence of scapular bony morphology and re-tear rates and patient-reported outcomes after rotator cuff repair. Studies were reviewed by two authors. Results A total of 615 unique titles and 49 potentially relevant abstracts were reviewed, with eight published manuscripts identified for inclusion. Two of three papers reported no relationship between these acromion index and rotator cuff re-tear rate, while one paper found an increased re-tear rate. All three studies on critical shoulder angle found a significant association between critical shoulder angle and cuff re-tear rate. There was no clear relationship between any bony morphologic measurement and patient-reported outcomes after rotator cuff repair. Conclusions Rotator cuff re-tear rate appears to be significantly associated with the critical shoulder angle and glenoid inclination, while not clearly associated with acromial morphologic measurements.

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Critical shoulder angle is an effective radiographic parameter that is associated with rotator cuff tears and osteoarthritis: a systematic review

Journal of ISAKOS Joint Disorders & Orthopaedic Sports Medicine ◽

10.1136/jisakos-2018-000255 ◽

2019 ◽

Vol 4 (2) ◽

pp. 113-120

Author(s):

Gabriel Kuper ◽

Ajaykumar Shanmugaraj ◽

Nolan S Horner ◽

Seper Ekhtiari ◽

Nicole Simunovic ◽

...

Keyword(s):

Systematic Review ◽

Rotator Cuff ◽

Predictive Value ◽

Rotator Cuff Tears ◽

Radiographic Parameter ◽

Rater Reliability ◽

Critical Shoulder Angle ◽

Patient Reported ◽

Shoulder Angle ◽

Shoulder Pathologies

ImportanceThe critical shoulder angle (CSA) is a relatively new radiographic parameter correlated with pathologies such as rotator cuff tears and osteoarthritis.ObjectiveThe purpose of this systematic review was to: (1) determine the degree of correlation between the CSA and shoulder pathologies, (2) determine the reliability of measuring CSA between (inter-rater reliability) and within (intrarater reliability) clinicians, (3) assess the accuracy of different imaging modalities used for measuring the CSA and (4) determine the association of CSA with patient outcomes after surgery.Evidence reviewThe electronic databases MEDLINE, EMBASE and PubMed were searched in March 2018 for relevant studies. The results are presented in a narrative summary.FindingsA total of 26 studies and 4563 patients satisfied the inclusion criteria. The majority of CSAs were measured using radiographs (98.2%) in neutral rotation (72.9%). Significant associations (p<0.05) were found between lower CSAs (<30°) and osteoarthritis, and higher CSAs (>35°) with primary rotator cuff tears and the risk of re-tear following a repair. The CSA has excellent intrarater (intraclass correlation coefficient (ICC) 0.903 to 0.996) and inter-rater reliability (ICC 0.869 to 0.980) when measured with radiographs. High variability in measurements was found when using MRI. The CSA, however, is not a clear, significant independent predictor (p>0.05) of outcomes after the surgical management of shoulder pathologies.Conclusions and relevanceThe CSA is an effective radiographic parameter that is associated with rotator cuff tears and osteoarthritis. Lower CSAs (<30°) are associated with osteoarthritis, whereas higher CSAs (>35°) are associated with primary rotator cuff tears and re-tear after arthroscopic repair. Currently, there is a limited predictive value of the CSA in patient-reported outcomes after rotator cuff repair. The CSA is measured with high intrarater and inter-rater reliability for both radiographs and CT scans. Measuring the CSA using radiographs with the arm in the neutral rotation is currently recommended. Future studies are required to further investigate how best use the CSA to guide patient management and its predictive value.Level of evidenceIV.

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