Schulterinfo.ch - Tendons - SAPS - subacromial pain syndrome
Schulterinfo.ch
Abstract
Also called shoulder impingement or subacromial impingement, subacromial pain syndrome is a painful condition, in which tendons of the rotator cuff or the subdeltoid bursa become entrapped due to narrowing of the subacromial space. Space narrowing can be the result of chronic mechanical stress or anatomical changes around the subacromial space whereby various causes come into question.
As the subacromial space narrows even more during abduction and elevation of the arm, a characteristic motion independent ‘’painful arc’’ can be described between 60° and 120°.
Suspicion is substantiated by clinical tests and is confirmed by imaging such as x-ray, MRI or ultrasound.
Treatment Is dependent on the underlying cause of the impingement and ranges from physical therapy, anti-inflammatory drugs and corticosteroid-injections to surgical intervention concentrating on repairing damaged tendons and expanding the subacromial space.
Subacromial pain syndrome (SAPS) is a pathology in which parts of the soft tissue of the rotator cuff are affected by narrowing of the space below the acromion, or muscular imbalance around the humeral head leading to entrapment of anatomical structures between the acromion and the humerus.
SAPS can be divided into two different categories:
- Primary SAPS in which anatomical changes result in narrowing of the subacromial space [1]
- Bony narrowing on the cranial side (e.g., osteophytes, os acromiale or a hooked acromion)
- Condition after fracture of the acromion or greater tubercle
- Subdeltoid/subacromial bursitis
- Calcific tendinitis
- Secondary SAPS in which impingement stems from a functional deficit of centring the humeral head properly, resulting in a shift of the centre of rotation while elevating, entrapping soft tissue caudally [1]
- Rotator cuff tear
Subsequently, tendons of the supraspinatus and the long biceps are mechanically irritated, resulting in pain for the patient. It should be noted that often there is no single root cause for developing SAPS, but rather an interplay of anatomical narrowing and deficits in centring the humeral head [1].
Incidence was found highest in the sixth decade of life, where up to 74% of patients suffer from any form of SAPS [1]. It is, however, difficult to name a specific value for certain age groups since rotator cuff tears and SAPS are concomitant pathologies, which reinforce each other in their pathomechanisms.
Patients suffering from SAPS usually are over age 40 and experience persistent anterolateral pain in the affected shoulder, which augments while moving the arm [1]. Almost pathognomonic is the painful arc in which patients describe pain when elevating or abducting the arm between 60° and 120°. Distinct pain during the night with problems sleeping on the affected shoulder has also been reported, especially with largely inflamed bursae [1].
Depending on the aetiology, additional symptoms such as weakness or pain during rotational movement in the shoulder may present. For further information please visit rotator cuff tear or calcific tendinitis.
Clincal history should contain the several dimensions of pain as well as past traumas that might be of trivial nature. Often patients themselves report about the painful arc, without specific testing beforehand.
Clinical examination is very valuable and may strengthen one’s suspicion. Scapular dyskinesia and glenohumeral instability should be assessed since it may favour SAPS [1]. Active and passive range of motion should be examined as well, where the painful arc should be reproducible [1].
Additionally, a combination of multiple specific tests can increase the probability of diagnosing SAPS correctly. No single test is accurate enough to rule in or rule out a subacromial impingement [2].
- Painful arc test
- The patient is asked to fully abduct and elevate the arm. If pain is present between 60° and 120° of abduction/elevation, it indicates a condition of the subacromial space
- Neer test
- The patient is asked to sit upright on the table or stand with the arm, which is to be examined, in full internal rotation. The examiner applies pressure to the scapula with one hand and the other is placed below the elbow. The examiner then proceeds to fully flex the shoulder, which should aggravate the pain in the painful arc and make the test positive.
- Hawkins-Kennedy test
- The patient is either sitting upright or standing. The examiner places the shoulder to 90° anteversion and flexes the elbow to 90°. With one hand grasping the patient’s wrist and the other hand grabbing the elbow, the patient’s wrist is quickly pulled downward, creating internal rotation in the shoulder. If the pain is reproduced, this can be interpreted as a positive sign.
- Diagnostic infiltration
- If pain decreases during the painful arc or Neer test after an infiltration with local anaesthetics, this could be an indicator for SAPS as well.
The Hawkins-Kennedy and Neer test have higher sensitivity than specificity and therefore patients with negative tests are more likely not to have SAPS [3]. If rotator cuff tears are suspected, specific testing for muscles of the rotator cuff should be executed. For more information about diagnostic tests of the rotator cuff muscles please visit rotator cuff tears.
High resolution Ultrasound and if necessary combined conventional radiographs are the most valuable diagnostic imaging tools available [2]. MRI might bring added value if rotator cuff tears need to be assessed for surgery [2]. Potential signs of SAPS or underlying conditions are listed below. For images please visit Radiopaedia.
- X-ray in AP-/Y-/Transaxillary-view
- Evaluation of the coraco-acromial arc
- Evaluation of osteoarthritis in the glenohumeral and acromioclavicular joint
- Screening out of calcific tendinitis
- Ultrasound
- Evaluation of tendons of the rotator cuff
- Evaluation of rotator cuff muscles
- Evaluation of muscle atrophy and fatty infiltration
- Evaluation of labrum and bursa
- Dynamic examination
- MRI
- Evaluation of tendons of the rotator cuff
- Evaluation of muscle atrophy and fatty infiltration
- Evaluation of labrum and bursa
- Acromioclavicular Osteoarthritis
- Glenohumeral Osteoarthritis
- Calcific tendinitis
- Rotator cuff tear
- Lesion of the long biceps tendon
Note: These diagnoses can be found concomitant and if present should be treated accordingly.
As always, therapy depends on the underlying pathology causing the complaint. In the acute phase the administration of NSAIDs and initial rest for 1-2 weeks is advised [2]. Patients with severe pain might need a corticosteroid injection in close proximity to the rotator cuff tendon, as it was found to be particularly effective in the first 8 weeks [2]. After a short resting period, low intensity physical therapy with focus on eccentric training, scapular stabilisation and improvement of posture is suggested [2].
In case of calcific deposits, extracorporeal shock wave therapy can be considered, but is ill-advised in the acute phase [2].
If conservative treatment fails or there is evident structural damage, surgery serves as another treatment option. Depending on the situation, acromioplasty, bursectomy or removal of osteophytes is indicated [1, 2]. Indications for reconstruction of symptomatic rotator cuff tears can be found under rotator cuff tears.
Prognosis and progressive course of disease
The outcome is very favourable. After undergoing conservative and/or surgical treatment, up to 80% of cases show good to very good results [1]. Studies have found that surgery and conservative treatment have roughly the same outcome [1]. However, there are circumstances in which surgery proofs more effective. It favours young patients with high functional requirements [1].
Prognosis is poorer the longer the duration of shoulder pain [2]. Clinicans should be aware that >3 months of shoulder pain is a poor prognostic factor, when deciding on treatment options [2].
- Garving C, Jakob S, Bauer I, Nadjar R, Brunner UH: Impingement syndrome of the shoulder. Dtsch Arztebl Int 2017; 114: 765–76. DOI: 10.3238/arztebl.2017.0765
- Diercks, Ron, Carel Bron, Oscar Dorrestijn, Carel Meskers, René Naber, Tjerk de Ruiter, Jaap Willems, Jan Winters, and Henk Jan van der Woude. 2014. "Guideline For Diagnosis And Treatment Of Subacromial Pain Syndrome". Acta Orthopaedica 85 (3): 314-322. doi:10.3109/17453674.2014.920991.
- Alqunaee, Marwan, Rose Galvin, and Tom Fahey. 2012. "Diagnostic Accuracy Of Clinical Tests For Subacromial Impingement Syndrome: A Systematic Review And Meta-Analysis". Archives Of Physical Medicine And Rehabilitation 93 (2): 229-236. doi:10.1016/j.apmr.2011.08.035.
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