There are 4 types of impingement:
Subacromial impingement syndrome (external impingement),
Internal impingement, posterosuperior type
Internal impingement, anterosuperior type
The impingement described above is also known as “external” or subacromial impingement. Subacromial impingement syndrome has both primary and secondary forms. Primary impingement is due to structural changes that mechanically narrow the subacromial space; these include bony narrowing on the cranial side (outlet impingement), bony malposition after a fracture of the greater tubercle or an increase in the volume of the subacromial soft tissues – due to for example subacromial bursitis or calcific tendinitis – on the caudal side. Secondary impingement results from a functional disturbance of centering of the humeral head, such as muscular imbalance, leading to an abnormal displacement of the centre of rotation in elevation and thereby to soft tissue entrapment.
A second type of impingement is “Internal impingement”.
There are 2 types. The more common postero-superior type refers to impingement of the rotator cuff against the posterior superior labrum which occurs when the shoulder is brought into cock-up position during a forceful throwing action. It is more commonly seen in overhead sports such as baseball, cricket, volleyball and others. Often there is a posterior capsular tightness associated with it. Physiotherapy and a staged muscle rehabilitation and return to sport program are first lines treatment. When tears occur in the rotator cuff and/or the labrum, surgical repairs may be needed.
Internal Impingement of the anterosuperior type is significantly less common. It involves an impingement of the subscapularis tendon between the anterior humeral head and the anterosuperior glenoid and labrum during forward flexion of the arm. When the arm is in a position of horizontal adduction and internal rotation, the undersurface of the reflection pulley and the subscapularis tendon impinges against the anterosuperior glenoid rim. In this context, lesions of the long head of the biceps (LHB), the pulley, and the rotator cuff have been associated with it.
Examination for impingement
Hawkins test; Neer sign; Jobe empty can test; Painful arc…
Investigations for impingement
X-rays and Ultrasound Scan to start, +/-MRI
Literature suggests combined treatments composed of exercise and other therapies tended to yield better effects than single-intervention therapies. Localized drug injections that were combined with exercise showed better treatment effects than any other treatments, whereas worse effects were observed when such injections were used alone.
It usually involves an arthroscopic subacromial decompression. During the operation, the proud anterior acromion is shaved to a flat surface, the Coraco-acromial ligament is released and the thickened subacromial bursa is trimmed to reduce its bulk.
The content of this article is intended to give a personal summary of a shoulder condition. It is intended for the exclusive viewing of qualified Australian medical general practitioners only.
A medical practitioner should only consider adopting or recommending the opinions of the author and proposed approach for the treatment of patients covered in this article, after performing normal clinical practice. This should include a thorough medical history, assessment, and detailed clinical examination supported with relevant scans and other medical tests.
In all cases, it is up to the individual medical practitioner to exercise his/her own discretion to determine the appropriateness of adopting or recommending the opinions and approach of the article for the treatment of patients.
The contents of the article cannot and does not purport to provide an exhaustive detailed analysis of this and all shoulder conditions and potential treatments. A further in-depth study from medical textbooks, publications and other medical literature is recommended
for each individual shoulder condition. If you are not a medically qualified person, you should seek the advice of your medical practitioner or other qualified health provider with any questions you may have regarding a medical condition.