[19] Subacromial Impingement Syndrome Flashcards
What does subacromial impingement syndrome (SAIS) refer to?
Inflammation and irritation of the rotator cuff tendons as they pass through the subacromial space
What does inflammation and irritation of the rotator cuff tendons as they pass through the subacromial space result in?
Pain, weakness, and reduced range of motion within the shoulder
What does SAIS encompass?
A range of pathologies, including rotator cuff tendinosis, subacromial bursitis, and calcific tendonitis
What do the pathologies leading to SAID all result in?
Attrition between the coracoacromial arch and the supraspinatus tendon or subacromial bursa
Who does SAIS most commonly occur in?
Patients under 25 years old, typically in active individuals or manual professions
What % of shoulder pain presentations are SAIS?
Around 60%
Where does the subacromial space lie?
Below the coracoacromial arch, and above the humeral head and greater tuberosity of the humerus
What does the coracoacromial arch consist of?
Acromion
Coracoacromial ligament (anterior to the acromioclavicular joint)
The coracoid process
What runs within the subacromial space?
The rotator cuff tendons
The long head of the biceps tendon
The coraco-acromial ligament
What are the structures running within the subacromial space all surrounded by?
The subacromial bursa
What is the function of the subacromial bursa?
It helps reduce friction between these structures
What can the underlying cause of SAIS be divided into?
Intrinsic and extrinsic mechanisms
What do the intrinsic mechanisms of SAIS involve?
Pathologies of the rotator cuff tendons due to tension
What are the intrinsic mechanisms of SAIS?
Muscular weakness
Overuse of the shoulder
Degenerative tendinopathy
How can muscular weakness cause SAIS?
Weakness in the rotator cuff muscles can lead to muscular imbalances, resulting in the humerus shifting proximally towards the body
How can overuse of the shoulder cause SAIS?
Repetitive microtrauma can result in soft tissue inflammation of the rotator cuff tendons and the subacromial bursa, leading to friction between the tendons and coracoacromial arch
How can degenerative tendinopathy cause SAIS?
Degenerative changes of the acromion can lead to tearing of the rotator cuff, which allows for proximal migration of the humeral head
What do the extrinsic mechanisms of SAIS involve?
Pathologies of the rotator cuff tendons due to external compression
What are the extrinsic mechanisms of SAIS?
Anatomical factors
Scapular musculature
Glenohumeral instability
What anatomical factors can cause SAIS?
Congential or acquired anatomical variations in the shape and gradient of the acromion
How can the scapular musculature cause SAIS?
A reduction in function of the scapular muscles may result in reduction in size of subacromial space
Which scapular muscles in particular can a reduction in function of be important in the development of SAIS?
Serratus anterior and trapezius
What do the serratus anterior and trapezius normally do?
Allow the humerus to move past the acromion on overhead extension
How can glenohumeral instability cause SAIS?
Any abnormality of the glenohumeral joint or weakness in the rotator cuff muscles can lead to superior sublaxation of the humerus, causing increased contact between the acromion and subacromial tissues
What is the most common symptom of SAIS?
Progressive pain in the anterior superior shoulder
What are the features of the pain in SAIS?
It is classically exacerbated by abduction in the affected shoulder, and relieved by rest
It may be associated with weakness and stiffness secondary to the pain
What specific examination tests can be done in SAIS?
Neers Impingement Test
Hawkins test
How is a Nerve Impingement Test performed?
The arm is placed by the patient’s side, fully internally rotated and then passively flexed
What is a positive Nerve Impingement Test?
If there is pain in the anterolateral aspect of the shoulder
How is Hawkins test performed?
The shoulder and elbow are flexed to 90 degrees, with the examiner then stabilising the humerus and passively internally rotating the arm
What is a positive Hawkins test?
If pain is elicited in the anterolateral part of the shoulder
What are the differential diagnoses for SAIS?
Muscular tear
Neurological pain
Frozen shoulder syndrome
Acromioclavicular pathology
Give two examples of muscular tears that could be differentials for SAIS
Rotator cuff tear
Long head of biceps tear
How can a muscular tear be differentiated from SAIS?
In a muscular tear, the weakness will persist despite the shoulder pain being relieved
Give 3 examples of neurological pain that could be differentials for SAIS
Thoracic outlet syndrome
Cervical radiculopathy
Brachial plexus injury
How can neurological pain be differentiated from SAIS?
In neurological pain, any weakness will likely be associated with paresthesia and/or pain, yet the weakness will persist despite the shoulder pain being relieved
How can frozen shoulder syndrome be differentiated from SAIS?
In frozen shoulder syndrome, stiffness will persist even if the pain is relieved
What acromioclavicular pathology may be a differential for SAIS?
Acromioclavicular arthritis
Glenohumeral arthritis
How can acromioclavicular pathology be differentiated from SAIS?
Acromioclavicular pathology presents with a more generalised pain
How is a diagnosis of SAIS made?
It is a clinical diagnosis, however is often confirmed via additional imaging
What is often the mainstay of imaging for SAIS?
MRI imaging of the affected shoulder
What features can be seen on MRI imaging in SAIS?
Formation of subacromial osteophytes and sclerosis
Subacromial bursitis
Humeral cystic changes
Narrowing of the subacromial space
What is the mainstay of treatment in most cases of SAIS?
Conservative management
What is involved in the conservative management of SAIS?
Sufficient analgesia
Regular physiotherapy
What analgesia is given in SAIS?
Typically NSAIDs
What should physiotherapy include in SAIS?
Postural, stability, mobility, and stretching exercises
What can be trialled for those who require further intervention following conservative management for SAIS?
Corticosteroid injections into the subacromial space
What should patients with SAIS be educated regarding?
Adequate warm up techniques
Monitoring for early signs of worsening impingement
When is surgical intervention recommended in SAIS?
If it persists beyond 6 months without response to conservative management
Which patients with SAIS is conservative management particularly useful in?
Patients with a reduced range of movement
What kind of surgery is most commonly used in SAIS?
Arthroscopic
What techniques can be used in SAIS surgery?
Surgical repair of muscular tears
Surgical removal of subacromial bursa
Surgical removal of a section of the acromion
What muscular tears are most commonly repaired in SAIS surgery?
Supraspinatus and long head of biceps tendon
What results from surgical repair of muscular tears in SAIS?
Improvement in range of motion
What results from surgical removal of the subacromial bursa in SAIS?
Increases subacromial space and reduces pain
What is the surgical removal of a section of the acromion known as?
An acromioplasty
What results from an acromioplasty?
Increases the subacromial space and reduces pain
What is the benefit of surgical decompressed over arthroscopy alonr?
Recent evidence shows it provides no extra benefit, and the benefits that are seen from surgical intervention might only be placebo effect or increased post-operative physiotherapy
What are the complications of SAIS?
Rotator cuff degeneration and tear
Cuff tear arthropathy
Complex regional pain syndrome
How effective is conservative management in SAIS?
If diagnosed and assessed early, SAIS resolves with conservative management in 60-90% of patients
