Shoulder Impingement Explained: Anatomy, Theories & Types

Why does the shoulder hurt when you lift the arm overhead? This episode explains shoulder impingement: the coracoacromial arch, the extrinsic and intrinsic theories, five types of impingement, and what happens to the rotator cuff tendon over time. Explore RadWeave, radiology reporting, templates and teaching cases in one workspace: https://radweave.ai CHAPTERS 0:00 Why the shoulder hurts overhead 0:10 The coracoacromial arch 0:24 Supraspinatus tendon and the subacromial bursa 0:38 Raising the arm: the space gets smaller 0:45 Extrinsic vs intrinsic theory 1:20 The five types of impingement 1:58 The tendon cascade: tendinosis, partial tear, full-thickness tear 2:21 A teaching model, not a proven rule 2:42 What MRI can and cannot show 2:48 Three things to remember REFERENCES 1. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972;54(1):41-50. 2. Neer CS 2nd. Impingement lesions. Clin Orthop Relat Res. 1983;(173):70-77. 3. Bigliani LU, Morrison DS, April EW. The morphology of the acromion and its relationship to rotator cuff tears. Orthop Trans. 1986;10:228. 4. Gerber C, Terrier F, Ganz R. The role of the coracoid process in the chronic impingement syndrome. J Bone Joint Surg Br. 1985;67(5):703-708. 5. Walch G, Boileau P, Noel E, Donell ST. Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: an arthroscopic study. J Shoulder Elbow Surg. 1992;1(5):238-245. 6. Habermeyer P, Magosch P, Pritsch M, Scheibel MT, Lichtenberg S. Anterosuperior impingement of the shoulder as a result of pulley lesions: a prospective arthroscopic study. J Shoulder Elbow Surg. 2004;13(1):5-12. 7. Goutallier D, Postel JM, Bernageau J, Lavau L, Voisin MC. Fatty muscle degeneration in cuff ruptures. Clin Orthop Relat Res. 1994;(304):78-83. 8. Beard DJ, et al. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet. 2018;391(10118):329-338. 9. Karjalainen TV, et al. Subacromial decompression surgery for rotator cuff disease. Cochrane Database Syst Rev. 2019;1:CD005619. Educational content only. It is not medical advice and does not replace clinical judgment. #radiology #shoulderMRI #rotatorcuff