The term impingement syndrome was initially introduced by Dr Charles Neer to describe a wide range of pathologies of the shoulder that presented with similar symptoms and was impossible to differentiate with the use of clinical tests and plain x-rays. The assumption is that the anteriorinferior aspect of the acromion and bone spurs that form in that area can cause rotator cuff tears or tendinosis. Of note at the time of introduction of this term there was no arthroscopy, no magnetic resonance imaging and no ultrasound of the musculosketal system. Partial thickness tears, rotator cuff tears, tendinosis of the supraspinatus and posterior capsular tightness can now be diagnosed more accurately. We suggested to make every effort to establish a diagnosis and avoid using the term impingement syndrome.
The clinical tests used to diagnose impingement syndrome are performed with the arm abducted or forward flexed more than 90 degrees. The following video shows that with the pull of the supraspinatus the "footprint" of the rotator cuff clears the anterior-inferior area of the acromion or otherwise known as the area of shoulder impingement, at significantly lower angles of rotation of the arm (video from University of Washington, Department of Orthopaedics, for more information see shoulderarthritis.blogspot.com)
The following animations demonstrate the position of the arm during the most commonly used clinical tests established for the diagnosis of "impingement syndrome". The 3D animation is a simulation of a shoulder that was reconstructed from at CT scan of a patient diagnosed with the so called "impingement syndrome". For more information please read: http://www.ncbi.nlm.nih.gov/pubmed/22005869
Published evidence relevant to the diagnosis of impingement syndrome of the shoulder.
Papadonikolakis A1, McKenna M, Warme W, Martin BI, Matsen FA 3rd. J Bone Joint Surg Am. 2011 Oct 5;93(19):1827-32.
