Impingement of the supraspinatus tendon can occur anywhere under the subacromial roof which is created by the acromion and the coracoacromial ligament (CAL).
The musculoskeletal ultrasound (MSKUS) shoulder protocol of the European Society of MusculoSkeletal Radiology advises to scan the CAL to see the interaction with the supraspinatus. Boudier-Revéret et al. (2019) advise to use MSKUS for dynamic assessment to see if the CAL is in play. Both sources advise to scan the CAL longitudinally, placing the transducer in between the coracoid process and acromion.
We advise, based on the thousands of shoulders we scanned, to scan the CAL dynamically in transverse plane instead of the proposed longitudinal plane. Connecting the transducer between the transverse CAL, and longitudinal supraspinatus tendon insertion, gives you truly a much clearer picture of the sonoanatomy, the tissues involved, whether there is an impingement or not, and the sonopathological signs.
The dynamical movements that have to be made depend on the patients’ complaint. It could be abduction/adduction or internal/external rotation in neutral position. But in overhead (athlete) problems it can also be done by making an internal/external rotation with the shoulder in abduction.
PubMed URL to the article: http://bit.ly/2RyIOnb