The influence of critical shoulder angle on secondary rotator cuff insufficiency following shoulder arthroplasty

Abstract Background The success of shoulder arthroplasty, both reverse and anatomical, depends on correcting the underlying glenoid deformity especially in patients with an osteoarthritis. We hypothesized that the distribution of glenoid version and especially inclination are underestimated in the shoulder arthritis population, and also that superior glenoid inclination can be detected through 3-dimensional (3D) software program of computed tomography (CT) to a greater proportion in patients with rotator cuff insufficiency, but also in patients with osteoarthritis with an intact rotator cuff. Because of the influence of rotator cuff imbalance on secondary glenoid wear the values of the critical shoulder angle (CSA) and the fatty infiltration of the rotator cuff are further analyzed. The aim of our study is to determine; 1) the distribution of glenoid inclination and version; 2) the relationship between glenoid inclination, version, the critical shoulder angle (CSA) to the status of the rotator cuff; 3) the proportion of patients with both an intact rotator cuff and a superior inclination greater than 10°. Methods A total of 231 shoulders were evaluated with X-ray images, 3-dimentional (3D) software program of computed tomography (CT), and magnetic resonance imaging. The cohort was divided into 3 groups according to their inclination angles and also grouped as intact-rotator cuff and torn-cuff group. Results The median (min/max) values for the 231 shoulders were 8° (− 23°/56°) for the inclination angle, − 11°(− 55°/23°) for the version angle, and 31.5°(17.6°/61.6°) for the CSA. The majority of the glenoids were found to show posterior-superior erosion. Glenoid inclination angle and CSA were significantly higher in torn-cuff group when compared with intact-cuff group (P < 0.001, both). The rotator cuff tears were statistically significant in high inclination group than low inclination group and no inclination group (p < 0.001). In the high inclination group, 41 of 105 (39%) shoulders had an intact rotator cuff, in about 18% of all shoulders. Conclusion Our findings show that 3D evaluation of glenoid inclination is mandatory for preoperative planning of shoulder replacement in order to properly assess superior inclination and that reverse shoulder arthroplasty may be considered more frequently than as previously expected, even when the rotator cuff is intact. Level of evidence Level 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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