Curr Rev Musculoskelet Med (2009) 2:51–55 53 to the impingement. MRI and CT scans are useful for [11]. The latter distance is measured best on an axial MRI further delineating coracoid or subcoracoid anatomy. An scan with the humerus in maximal internal rotation. axial CT view is used to assess the coracoid index, which is In asymptomatic patients, the average coracohumeral a measurement of the lateral projection of the coracoid interval (Fig. 3) measures 11 mm in maximal internal process beyond a line tangential to the articular surface of the glenoid [13]. This is a linear measurement in milli- rotation, with none measuring \4 mm [16]. Symptomatic patients had an average interval of 5.5 mm in maximal metres. The average index in 67 normal shoulders was internal rotation. This study by Friedman et al. [16] also 8.2 mm [13]. It has also been suggested that there should noted that there is no redundancy of the subscapularis be a minimum distance of 6.8 mm between the coracoid tip tendon in asymptomatic patients with the arm in full and the closest portion of the proximal part of the humerus internal rotation. The sensitivity of this particular position Fig. 4 Algorithm for the diagnosis and management of coracoid impingement [7, 23, 24] Algorithm for the Diagnosis and Management of Coracoid Impingement Patient with anterior shoulder pain with increased pain from cross arm adduction, forward elevation and internal rotation of shoulder? Tender over coracoid process and pain reproduced on passive forward flexion and medial rotation in varying degrees of horizontal adduction? Relief with injection of Local anaesthetic into subcoracoid region? Yes Yes Yes Perform Plain X-rays of shoulder (AP and lateral view perpendicular to plane of scapula) looking for laterally projecting coracoid Present? Treat as coracoid impingement Conservative measures: Pain relief, avoidance of provocative positions, physiotherapy Unsuccessful? Surgery : Coracoplasty Combination of coracoacromial ligament resection and acromioplasty Anterior shoulder stabilisation Arthroscopic treatment No No Not Present No Consider other causes of shoulder pain such as : Thoracic outlet syndrome, instability, Avascular necrosis of humeral head, Degenerative osteoarthritis, Brachial plexus injury Consider other causes of impingement: Rotator cuff pathology Arthritis of the glenohumeral joint Adhesive capsulitis Bursitis Intra-muscular adhesions Acromioclavicular pathology Subscapular nerve injury Cervical disc lesion Cervical nerve root lesion Subscapular nerve injury Thoracic outlet syndrome Perform CT/MRI scan looking at coracoid index and coracohumeral interval Coracoid index less than 6.8mm? Coracohumeral interval less than 5.5mm? Yes No