Subacromial Pain Syndrome

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Original Editor - David Drinkard, Dorien De Strijcker

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Search Strategy

Key Words:

• Subacromial impingement + Diagnosis / Therapy / Epidemiology / Etiology / Rehabilitation 
• Hawkins-Kennedy test

Search engines : Pubmed / Web of knowledge

Limits : Humans - Published in the last 3 years

Definition/Description

Subacromial (SA) impingement is defined as the mechanical compression of subacromial structures between the coraco-acromial arch and the humerus during active elevation of the arm above shoulder high.

Clinically Relevant Anatomy

Subacromial structures.jpg

Structures involved in subacromial impingment:

• the coracoacromial arch composed of acromion, processus coracoideus and ligamentum coracoacromiale
• the humerus
• the tendons of the Rotator Cuff 
• the long head of de m. biceps brachii
• the subacromial bursa
• shoulder capsule

The subacromial space is the margin between the superior portion of the humeral head and the inferior portion of the acromion. It contains:

• belly and tendon of the supraspinatus muscle
• long head of the biceps muscle
• subacromial bursa

The shape of the acromion plays an important role in impingment syndromes. 3 types of acromial shape can be distinguished:

• Type I acromion: flat shape
• Type II acromion: curved shape
• Type III acromion: hooked shape (most likely to contribute to impingement and irritation)
  

Bony spurs at the bottom aspect of the acromion can also be involved.

Epidemiology /Etiology

Impingement syndrome occurs in one out of three persons, half of whom still report pain after three years.

Subacromial impingement occurs when the subacromial space is narrowed and weak structures in that space get compressed. Several causes for subacromial impingment have been detected:

• Anatomical variations such as narrow SA space, type II or III acromion, osteophytes.
• Rotator cuff weakness, causing the humeral head to drift more superior.
• Chronic rotator cuff irritation due to overuse.
• Posterior GH capsule tightness
• Poor posture (forward shoulder posture can cause functional narrowing of SA space)
• Abnormal muscle activation

Mentioned biomedical aspects but also psychological factors as kinesiophobia or catastrophizing can have negative influence and thus cause chronic pain and disability.

Clinical Presentation

The shoulder pain during active elevation of the arm is usually reported at the anterior or lateral side of the shoulder. Activities performed with the involved arm below shoulder level are mostly not painful.

Onset is more of a gradual, degenerative condition rather than due to a strong external force. Therefore, patients have difficulty determining the exact time of onset. 

• First stage:

Moderate pain during exercise
No loss of strength
No limitation in movement

• Second stage:

Pain during ADL-activities and especially during the night
Loss of mobility

• Third stage:

Strong restriction in movement due to calcifications
Loss of muscle strength

Diagnostic Procedures

Diagnosis should be based on:

• History
• Clinical examination
• X-rays
• MRI

History and clinical examination are imparitive. X-rays may be used as an extra test detect sclerosis and osteophyte-formation on the acromion. The size of the subacromial space can also be measured. MRI can show full or partial tears in the tendons of the rotator cuff, cracks in the capsule and inflammation to weak structures.

Outcome Measures

add links to outcome measures here (also see Outcome Measures Database)

Examination

Also see Impingement Cluster page

Following tests help to confirm or rule out subacromial impingment syndrome:

• Hawkins-Kennedy
• Neer impingement test (useful screening test to rule out SAI)
• Painful Arc (between 60° and 120°) (useful screening and helpful confirming test to rule out SAI)
• Empty can (Jobe) (helpful test to confirm SAI)
• External rotation resistance tests (useful screening and helpful confriming test to rule out SAI)

Outcome Measures

add links to outcome measures here (see Outcome Measures Database)

Management / Interventions

Initially the use of the RICE-method (Rest, Ice, Compression and Elevation) is recommended. Further on, the patient can have non-steroidal anti-inflammatory drugs (NSAIDs) or analgesics as needed.

Treatment of subacromial impingement can be managed either operatively or non-operatively.

Medical Management (current best evidence)

• repair of the tissues that have been damaged due to repetitive trauma 
 --> often involved structures are: the supraspinatus muscle and/or tendon, proximal biceps tendon, or joint capsule.
• a bursectomy = removal of the subacromial bursa
• a subacromial decompression (SAD) = increase the SA space by removing:
                                                                - bony spurs 
                                                                - the coracoacromial ligament 
                                                                - even occasionally the most inferior portion of the acromion   

                                                                  (= acromioplasty)                      
The Neer (open) acriomioplasty requires a longer rehabilitation than the arthroscopic acromioplasty, so we prefer the last one.
In addition to surgery, non-operative rehabilitation is good option as well. There is evidence that non-operative rehabilitation, which is supervised, and arthroscopic subacromial decompression both decrease pain in the shoulder and increase function.[1] It can be that some people respond better on physical therapy management, while others respond better on surgery (medical management). 

Physical Therapy Management (current best evidence)

Non-operative treatment is attempted first, assuming there is no biceps or rotator cuff tear that will require surgery.
There are a lot of conservative treatments available:
• RICE-method (Rest, Ice, Compression and Elevation)
• physical therapy
• Shoulder manual therapy techniques
  --> in particular, have been shown to have a significant effect on improving pain levels
• acupuncture.[6]
Although exercise therapy alone has been shown to bring decreased pain, the addition of manual therapy further augments those gains and also aids in greater strength gains than exercise alone[7]. Thoracic spine thrust manipulation has been shown to be effective in producing short-term increases in subjective reports of function and decreases in pain in individuals with SAI[8] 

There are other modalities as well to relieve the pain, but we don’t know if these modalities speed up the healing:
• electronic stimulation
• ultrasound
• Low-level laser-therapy: have positive influence on all symptoms except muscle strength.[9]

Acromioplasty and/or manual therapy may be used alongside therapeutic exercise to improve functional and impairment-level gains, depending on severity of anatomic dysfunction involved. Although exercise treatment is a vital part of treatment for this condition, results showed no significant difference between home-based exercises and clinical exercise. Once manual therapy is no longer necessary and the patient has an adequate home exercise program, forma therapy is often no longer necessary. A website on which a physiotherapist easily can find some simple exercises a patient can do at home is: Revalidatie Herentals. This is a website of a Belgian hospital that is specialized in shoulder disorders.

Therapeutic exercise should include:  - rotator cuff strengthening
                                                       - lower and middle trapezius strengthening
                                                       - anterior and posterior shoulder stretching.[10]
It’s all about strengthening and stretching those muscles. Lower trap strengthening is important because individuals with impingement syndrome have been shown to demonstrate greater ratios of upper trap/lower trap activation than asymptomatic individuals[11]. Soft tissue mobilization to normalize muscle spasm and other soft tissue dysfunction has been shown to be effective alongside joint mobilizations to restore motion in treatment of SAI[12] There are no data available which can guarantee that surgical treatment is more effective than conservative treatment.[13]
 

Differential Diagnosis

There are a variety of shoulder conditions that can initially be confused with subacromial impingement, although a thorough examination is usually sufficient for identifying this condition.

Partial and full rotator cuff tears are  or rotator cuff tendinitis are often the result of subacromial impingement syndrome, but can occur without impingement and usually demonstrate some sort of lag sign upon evaluation.
Adhesive capsulitis, or "frozen shoulder", can also present with limitation of active arm elevation and significant shoulder pain; however, adhesive capsulitis usually presents with glenohumeral motion loss in a capsular pattern, meaning that external rotation and abduction are the two directions with the greatest magnitude of motion lost.
Further on, calcific tendinitis and an acute or chronic inflammation of the bursa subacromialis could be differential diagnosis, as well as a subluxating shoulder or thoracic outlet syndrome. [3]

Key Research

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Resources

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Clinical Bottom Line

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Recent Related Research (from Pubmed)

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• Arthroscopic tuberoplasty for subacromial impingement secondary to proximal humeral malunion

References

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[Category:Musculoskeletal/Orthopaedics]]

1. ↑ 1.0 1.1 TATE A.R., MCCLURE P.W., YOUNG I.A., SALVATOR R., MICHENER L.A. Comprehensive impairment-based exercise and manual therapy intervention for patients with subacromial impingement syndrome: a case series. The Journal of orthopaedic and sports physical therapy. 2010 Aug; 40(8): 474-93
2. ↑ Kachingwe AF, Phillips B, Sletten E, Plunkett SW. Comparison of Manual Therapy Techniques with Therapeutic Exercise in the Treatment of Shoulder Impingement: A Randomized Controlled Pilot Clinical Trial. The Journal of Manual Manipulative Therapy 2008;16(4):238-247.
3. ↑ 3.0 3.1 3.2 BIRRER R.B., O’CONNOR F.G. Sports medicine for the primary care physician. 3rd edition, Boca Raton: RCR PRESS, 2004.p507- 10
4. ↑ 4.0 4.1 KROMER T.O., DE BIE R.A., BASTIANENEN C.H.G. Effectiveness of individualized physiotherapy on pain and functioning compared to a standard exercise protocol in patients presenting with clinical signs of subacromial impingement syndrome. A randomized controlled trial. BMC Musculoskeletal Disorders. 2010 Jun 9; 11:114.
5. ↑ MICHENER L.A., WALSWORTH M.K., DOUKAS W.C., MURPHY K.P. Reliability and Diagnostic Accuracy of 5 Physical Examination Tests and Combination of Tests for Subacromial Impingement. Archives of Physical Medicine and Rehabilitation. 2009 Nov; 90(11): 1898-903
6. ↑ 6.0 6.1 DORRESTIJN O., STEVENS M., WINTERS J.C., VAN DER MEER C.,DIERCKS R.l. Conservative or surgical treatment for subacromial impingement syndrome? A systematic review.Journal of shoulder and elbow surgery board of trustees.2009 Jul-Aug;18(4):652-60
7. ↑ Bang MD, Deyle GD. Comparison of Supervised Exercise With and Without Manual Physical Therapy for Patients with Shoulder Impingement Syndrome. Journal of Orthopaedic and Sports Physical Therapy. 2000;30(3):126-137.
8. ↑ Boyles RE, Ritland BM, Miracle BM, Barclay DM, Faul MS, Moore JH, Koppenhaver SL, Wainner RS. The Short-term effects of thoracic spine thrust manipulation on patients with shoulder impingement syndrome. Manual Therapy. 2009, 14: 375-380.
9. ↑ YELDAN I., CETIN E., OZDINCLER A.R. The effectiveness of low-level laser therapy on shoulder function in subacromial impingement syndrome. Disability and rehabilitation. 2009; 31(11): 935–940
10. ↑ Kuhn JE. Exercise in the treatment of rotator cuff impingement: A systematic review and synthesized evidence-based rehabilitation protocol. Journal fo Shoulder and Elbow Surgery. 2009;18:138-160.
11. ↑ Smith M, Sparkes V, Busse M, Enright S. Upper and Lower trapezius muscle activity in subjects with subacromial impingement symptoms: Is there imbalance and can taping change it? Physical Therapy in Sport. 2009:10, 45-50.
12. ↑ Senbursa G, Baltaci G, Atay A. Comparison of conservative treatment with and without manual physical therapy for patients with shoulder impingement syndrome: a prospective, randomized clinical trial. Knee Surg Sports Traumatol Arthoscop. 2007;15:915-921.
13. ↑ KUHN J.E. Current evidence fails to show differences in effectiveness between conservative and surgical treatment of subacromial impingement syndrome. The Journal of Bone and Joint Surgery. 2010;92:474