Magnetic resonance (MR) imaging of seven volunteers with no history of shoulder instability demonstrated contact between the greater tuberosity and posterosuperior glenoid rim in all seven with the arm in full shoulder elevation and internally rotation, mimicking the impingement sign.
37) When impingement is not the cause of the inflammation, impingement signs are normally absent.
Impingement signs are a common finding, while the apprehension sign should be negative.
However, the pain and tenderness persisted on the coracoid process, and the coracoid impingement sign was still positive.
In this patient, the constant pain in the coracoid process at the first examination and after the operation and the positive coracoid impingement sign suggested coracoid impingement syndrome.
The clinical examination can be difficult because impingement signs can mimic acromioclavicular joint signs or an early frozen shoulder, so a directed injection of local anaesthetic into the area that appears to be the mostly likely origin of the pain can be the most important diagnostic tool.
In addition, an acromioplasty is performed in many cases where impingement signs are seen at surgery.
Acromioplasty must be performed only when there are clinical or intraoperative impingement signs
18) We also tracked the hips with radiographic impingement signs
(on the resurfacing side) and measured the acetabular component abduction angle.
At the six months follow-up visit, the patient was doing well, with full right shoulder range of motion, negative impingement signs
, and without tenderness on palpation over the acromion and AC joint.
Multidirectional instability may present with pain and impingement signs
, without obvious feeling of instability.
Burnett and coworkers (7) also found that 95% of their cohort with labral pathology had positive impingement signs
and lower rates of symptoms, such as a limp or a Trendelenburg sign.