Is there an association between the individual anatomy of the scapula and the development of rotator cuff tears or osteoarthritis of the glenohumeral joint?

Abstract

We hypothesised that a large acromial cover with an upwardly tilted glenoid fossa would be associated with degenerative rotator cuff tears (RCTs), and conversely, that a short acromion with an inferiorly inclined glenoid would be associated with glenohumeral osteoarthritis (OA). This hypothesis was tested using a new radiological parameter, the critical shoulder angle (CSA), which combines the measurements of inclination of the glenoid and the lateral extension of the acromion (the acromion index). The CSA was measured on standardised radiographs of three groups: 1) a control group of 94 asymptomatic shoulders with normal rotator cuffs and no OA; 2) a group of 102 shoulders with MRI-documented full-thickness RCTs without OA; and 3) a group of 102 shoulders with primary OA and no RCTs noted during total shoulder replacement. The mean CSA was 33.1° (26.8° to 38.6°) in the control group, 38.0° (29.5° to 43.5°) in the RCT group and 28.1° (18.6° to 35.8°) in the OA group. Of patients with a CSA > 35°, 84% were in the RCT group and of those with a CSA < 30°, 93% were in the OA group. We therefore concluded that primary glenohumeral OA is associated with significantly smaller degenerative RCTs with significantly larger CSAs than asymptomatic shoulders without these pathologies. These findings suggest that individual quantitative anatomy may imply biomechanics that are likely to induce specific types of degenerative joint disorders.

The morphometric anatomy of the delto-fulcral triangle: A 3D CT-based reconstruction study

“…6,8,11,[14][15][16][17][18][19] Anatomically, the three sides that create this triangle in the typical supraspinatus-outlet view are easily obtainable from both X-ray images and CT scans because the three osseous scapular landmarks are clearly visualised. Side 1 (AFLAC), arising from the antero-superior aspect of the coracoid process and ending at the lateral acromion, represented the ligamentous attachment of the coraco-acromial ligament that spans the area of the coraco-acromial arch, over which the deltoid muscle passes towards its humeral insertion at the deltoid tuberosity.…”

“…In addition, the inclusion of the lateral acromion landmark in Sides 1 and 2 was due to its association with degenerative changes in rotator cuff tears and omarthrosis. 16 Side 3 (AFPF), which commences at the antero-superior aspect of the coracoid process and passes posteriorly to posterior-most aspect of the acromion is inevitably the fulcrum axis, hence the referral of these landmarks as the anterior and posterior fulcrum points, respectively. 11,18 Both these distally-placed landmarks are common body-surface landmarks used in shoulder arthroscopy as they lie approximately parallel to the glenoid plane.…”

Natural History of Degenerative Rotator Cuff Tears

“…The authors concluded that the CSA is unlikely to be related to degenerative rotator cuff disease. The association of CSA and rotator cuff disease continues to be debated as some authors have noted a positive correlation of rotator cuff tears with a larger CSA [11][12][13]. …”

Predictors of Shoulder Degeneration in the KwaZulu-Natal Population of South Africa

“…Since the critical shoulder angle and acromion index are considered to be characteristic of subacromial pathology, there is much need for the evaluation of these biomechanical parameters as separate and interrelated predictors of shoulder degeneration in the South African population (Armfield et al, 2003;Moor et al, 2013;Bouaicha et al, 2014;Gerber et al, 2014;Spiegl et al, 2016). As the scapulo-humeral geometry related to these parameters present as static stabilisers, the relationship between the latter and the surrounding musculature determines the stability of the shoulder (Armfield et al;Moor et al, 2013;Gerber et al).…”

“…As the scapulo-humeral geometry related to these parameters present as static stabilisers, the relationship between the latter and the surrounding musculature determines the stability of the shoulder (Armfield et al;Moor et al, 2013;Gerber et al).…”