subacromial impingement

Subacromial

impingement with partial rupture of the supraspinatus tendon. However, no retraction or fatty degeneration of the supraspinatus muscle. Arthrosis of the acromio clavicular joint with capsule hypertrophy.

Wikipedia • CC BY-SA 3.0

Subacromial

impingement • Coracoacromial ligament ossification - Ganzer Fall bei Radiopaedia

Skalski, M. Coracoacromial ligament ossification. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-21721 • CC by-nc-sa 3.0 (modified)

Subacromial

impingement • Acromioclavicular arthritis - rotator cuff tear - Ganzer Fall bei Radiopaedia

Desai, P. Acromioclavicular arthritis - rotator cuff tear. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-10890 • CC by-nc-sa 3.0 (modified)

Subacromial

impingement • Acromial impingement : type III acromion - Ganzer Fall bei Radiopaedia

Jha, P. Acromial impingement : type III acromion. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-18992 • CC by-nc-sa 3.0 (modified)

Subacromial

impingement • Rotator cuff tear - Ganzer Fall bei Radiopaedia

Abdrabou, A. Rotator cuff tear. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-43578 • CC by-nc-sa 3.0 (modified)

Rotator cuff

tear • Supraspinatus partial tear with subacromial impingement - Ganzer Fall bei Radiopaedia

Dixon, A. Supraspinatus partial tear with subacromial impingement. Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-42429 • CC by-nc-sa 3.0 (modified)

Emergency

department diagnosis of supraspinatus tendon calcification and shoulder impingement syndrome using bedside ultrasonography. Supraspinatus tendon impingement under the acromion.

theultrasoundjournal.springeropen.com • CC-by-2.0

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Subacromial impingement is by far the most common form of shoulder impingement and occurs secondary to attrition between the coracoacromial arch and the underlying supraspinatus tendon or subacromial bursa, leading to tendinopathy and bursitis respectively.

Pathology

Etiology

acromial shape
- os acromiale
- type III acromion
- low lying acromion
- downsloping lateral acromion
- acromial spur
acromioclavicular joint degenerative disease
coracoacromial ligament ossification or thickening
shoulder instability
post-traumatic deformity
supraspinatus overdevelopment
chronic bursitis

Radiographic features

Primarily, subacromial impingement is a clinical diagnosis and one should not make a diagnosis or exclude it solely based on imaging. However, imaging has an important role in supporting the diagnosis, finding the possible cause as well as sequelae of impingement.

Static imaging modalities such as MRI and radiographs occasionally depict reduced subacromial distance as indirect evidence:

type III acromion
os acromiale
osteophytes extruding from the acromioclavicular joint inferiorly
subacromial-subdeltoid bursitis
lateral acromial slope/tilt
downsloping lateral acromion

Anecdotal experience also suggests that slight contact between the coracoacromial arch and the subacromial bursa can occur in healthy individuals; yet, significant contact or snapping between these two structures are not common in the absence of symptoms and suggest clinically relevant impingement .

Ultrasound

Dynamic ultrasound may depict abnormal contact between the coracoacromial arch and peritendinous tissue during shoulder abduction; however, dynamic diagnosis at ultrasound is not free of controversy: although earlier studies have demonstrated thickening of the subacromial bursa following shoulder abduction in symptomatic shoulders, a more recent investigation found no significant difference in the degree of bursal gathering in impingement patients compared with healthy volunteers .