What is Subacromial Impingement Syndrome?

Mechanical Etiology of Subacromial Impingement

Subacromial impingement represents mechanical irritation of the rotator cuff tendons (predominantly the supraspinatus) and subacromial bursa as they glide beneath the coracoacromial arch during humeral abduction. Subacromial bone spurs, hypertrophic acromioclavicular joints, or rotator cuff muscle imbalances narrow this critical corridor.

High-Risk Demographics

Athletes engaged in overhead sports (swimming, volleyball, tennis) and manual laborers performing repetitive reaching tasks face elevated susceptibility to cumulative microtrauma.

Classic Clinical Features

• Sharp anterolateral shoulder discomfort during 60° to 120° of arm elevation (painful arc)
• Nocturnal pain exacerbated by lying on the ipsilateral side
• Weakness and stiffness during behind-the-back reaching and overhead maneuvers
• Gradual loss of shoulder muscular endurance

Frequently Asked Questions

Can chronic impingement lead to a full rotator cuff tear?

Yes, persistent mechanical attrition compromises tendon vascularity, predisposing the tendon to partial and eventual full-thickness degenerative tears.

What does arthroscopic decompression involve?

Subacromial decompression (acromioplasty) arthroscopically resects inferior acromial spurs and releases the tight coracoacromial ligament, creating ample clearance for tendon excursion.