Subacromial impingement

Anatomy and mechanics of the subacromial space

The subacromial space lies between the shoulder roof (acromion) and the humeral head. The tendons of the rotator cuff - especially the supraspinatus tendon - and the subacromial bursa run in this sliding bearing. For pain-free movements, the harmonious interaction of the shoulder blade muscles (scapular control), the gliding ability of the bursa and the resilience of the tendons are crucial.

• Rotator cuff: supraspinatus, infraspinatus, subscapularis, teres minor
• Subacromial bursa: reduces friction between tendons and bones
• Shoulder roof (acromion) and AC joint: can influence the constriction through shape variations/projections
• Scapulohumeral rhythm: coordinates scapula and upper arm movements

If there is relative tightness - for example due to tendon swelling, bursitis or bony attachments - pain occurs primarily between 60° and 120° arm elevation (typical “pain arc”).

Causes and risk factors

Often there is a combination of structural and functional factors. A single cause is not always responsible; Often several aspects reinforce each other.

• Functional factors: Scapular dyskinesia, muscular imbalances (weak external rotators/scapula stabilizers), shortened anterior structures (pectoralis minor), limited thoracic spine mobility
• Overhead strain: repetitive activities in crafts, painting, throwing sports, CrossFit/shoulder presses
• Tendon overload/tendinopathy: age-related tissue changes, smoking, metabolic factors
• Structural tightness: acromion shape, osteophytes at the AC joint, subacromial spurs
• Calcification deposits (tendinosis calcarea): temporarily increase the tightness and irritate the bursa
• Consequences of injuries or poor posture: e.g. B. after a fall, prolonged immobilization, workplace ergonomics

Typical symptoms

• Pain when lifting/abducting the arm, especially between 60°–120° (Pain‑Arc)
• Pain at night, especially when lying on the affected side
• Stinging pain with quick or jerky movements
• Reduced strength and fatigue when working overhead
• Tenderness over the anterior/lateral acromion
• Sometimes snapping/rubbing (“crepitation”) when moving

Diagnostics: step by step

The diagnosis is based on anamnesis, physical examination and – if necessary – imaging tests. It is important to differentiate between tendon tears and other causes of pain.

• Clinical tests: Hawkins-Kennedy, Neer test, painful arch, Jobe test (supraspinatus), external/internal rotation testing, scapular movement
• Sonography: Assessment of the bursa, tendon structure, dynamic bottleneck situations, possibly calcium deposits; without radiation exposure
• X-ray: shape of the acromion, AC joint, bony spurs, calcium foci
• MRI (if necessary): Suspected partial/complete tear of the rotator cuff or unclear findings
• Diagnostic injection: short-term pain relief suggests subacromial involvement

In practice in Hamburg, the examination is carried out in a structured manner; Imaging procedures are usefully supplemented depending on the clinical findings.

Differential diagnoses

• Partial or complete rotator cuff tear
• Supraspinatus, infraspinatus, subscapularis or teres minor tendinopathy
• Calcified shoulder (tendinosis calcarea)
• AC joint osteoarthritis/irritation
• Biceps tendonitis (long biceps tendon, LBS)
• Adhesive capsulitis (frozen shoulder)
• Cervical radiculopathy, nerve irritation
• Scapulathoracic pain syndrome

Course and stages

The symptoms range from temporary bursitis to chronic tendon changes. Without control of the load, irritation can develop into tendinopathy; In individual cases, tears occur.

Conservative therapy: standard of initial treatment

The aim is to functionally reduce the tightness, calm inflammation and rebuild the resilience of the tendons. Typically, a structured program is followed over at least 6-12 weeks.

• Education & activity control: initially reduce pain-provocative overhead work, shift movements to the area with little pain
• Physiotherapy with a focus on: scapular stability (Serratus anterior, lower trapezius), strengthening external rotators, centering the humeral head
• Mobility: Pectoralis minor/anterior capsule stretch, posterior capsule stretch, mobilization of the thoracic spine
• Load progression: slow build-up (2-3 sessions/week), documented increase in reps/load
• Analgesics/NSAIDs (short-term, individually tailored) and local cooling in the acute phase
• Tape/orthosis: can provide short-term support (postural/scapular tape), but does not replace training
• Workplace ergonomics: monitor height, forearm support, break management, tool guidance below shoulder height

Many patients report noticeable relief within 6-8 weeks if exercises are carried out regularly and correctly. A realistic time window for sustainable adjustments is 3-4 months.

Injections: targeted inflammation calming

If pain blocks therapy, ultrasound-guided injection into the subacromial space may be considered. It is intended to provide short-term relief to enable exercise - it does not replace it.

• Local anesthetic (+/− low-dose cortisone) to calm inflammation and as a diagnostic test
• Indication: persistent pain despite adequate rest/physiotherapy
• Limited frequency: repeated cortisone administration can strain tendon tissue; weigh up individually
• Possible side effects: temporary increase in blood sugar, skin irritation, very rarely infection

The decision is made after information about the benefits and risks. In our practice, the placement is carried out under ultrasound control.

Regenerative procedures: careful indication

Biological procedures such as platelet-rich plasma (PRP) are discussed for tendinopathies. The study situation on isolated subacromial impingement is heterogeneous; Application can be considered in individual cases with accompanying rotator cuff tendinopathy.

• PRP: The aim is to modulate the healing response in tendinopathy; Benefits vary by study and protocol
• Shock wave therapy: especially for calcified shoulder (tendinosis calcarea) with evidence; limited to pure impingement
• Always provide information about evidence, costs and alternatives; conservative training remains the basis

Surgical options: when and for whom?

Surgery is not the first step in treatment. It can be considered if, despite correct conservative therapy, relevant symptoms persist for at least 3-6 months and there is a structural cause.

• Arthroscopic decompression/acromioplasty: Benefit in primary impingement without associated pathology is limited in studies; Indication especially for bony narrowness/spurs or AC osteophytes
• Treatment of accompanying findings: removal of calcium deposits, biceps tendon therapy, AC joint measures
• Rotator cuff reconstruction: if there is a proven tear and functional impairment
• Rehabilitation: depending on the procedure, several weeks; After tendon suturing, gradual build-up over months

Before an operation, goals, alternatives, realistic expectations and possible complications are discussed in detail. There can be no guaranteed result.

Rehabilitation, exercises and everyday tips

Consistency and technique are crucial. Exercises should be painless but noticeably demanding. Quality over quantity - it's better to drink regularly in small doses rather than rarely and too intensively.

• Sleep: lying on your back with a pillow under your arm or lying on your side on your healthy side with a supporting pillow
• Work: Minimize overhead work, keep the load close to your body, plan for micro-breaks
• Sport: no painful overhead drills for now; Technical coaching and measured re-entry
• Heat/cold: Cold in the acute phase, later heat therapy for muscle relaxation possible

Prevention and relapse prevention

• Regular training of the external rotators and scapula stabilizers
• Thoracic spine mobility, anterior chain stretching
• Slow increase in training volume and intensity (10-15% rule)
• Check workplace ergonomics, frequent changes in posture
• Reduce/quit smoking, promote general fitness and sleep quality

When to see a doctor? Warning signs

• Acute pain and significant loss of strength after trauma
• Persistent pain at night or at rest despite rest
• Severe restriction of movement, suspected frozen shoulder
• Numbness, tingling, circulatory problems
• Fever, redness, overheating of the shoulder

Early clarification helps to avoid incorrect loading and to plan the therapy precisely.

Your shoulder consultation in Hamburg

Our orthopedic practice at Dorotheenstrasse 48, 22301 Hamburg offers structured diagnostics and evidence-oriented, conservative treatment of subacromial impingement. If necessary, we incorporate sonography, targeted injections and interdisciplinary physiotherapy.