Subacromial Impingement Syndrome Flashcards
What is Subacromial impingement syndrome? (SAIS)
Inflammation and irritation of the rotator cuff tendons as they pass through the subacromial space.
This leads to pain, weakness and reduced range of motion within the shoulder.
Pathologies associated with SAIS
Rotator cuff tendinosis
Subacromial bursitis
Calcific tendinitis
All these result in an attrition between coracoacromial arch and supraspinatus tendon or subacromial bursa.
Epidemiology of SAIS
Under 25
Active individuals or in their manual professions.
Accounts for around 60% of all shoulder pain presentations (most common presentation)
Explain the subacromial space.
Lies below the coracoacromial arch and above the humeral head and greater tuberosity of the humerus.
Coracoacromial arch = Acromion, coracoacromial ligament and coracoid process.
What is found in the subacromial space?
Rotator cuff tendons
Long head of biceps tendon
Coraco-acromial ligament
The subacromial bursa surrounds these and help to reduce friction
Pathophysiology can be broken down into intrinsic and extrinsic mechanisms.
Intrinsic mechanisms.
Muscular weakness -> Leads to muscular imbalances causing humerus shifting proximally towards the body
Overuse of shoulder -> Microtrauma causing soft tissue inflammation of rotator cuff tendons and subacromial bursa. This causes friction between tendons.
Degenerative tendinopathy -> Leads to tearing of the rotator cuff, allowing for proximal migration of the humeral head.
Extrinsic mechanisms.
Anatomical factors -> Congenital or acquired
Scapular musculature -> Reduction in function of scapular muscles (serratus anterior and trapezius) can cause reduction in size of subacromial space.
Glenohumeral instability -> Abnormalities of GHJ or weaknes in rotator cuffs can lead to superior subluxation of humerus causing increased contact between acromion and subacromial tissues.
Clinical features of SAIS
Progressive pain in anterior superior shoulder
Exacerbated by abduction
Relieved by rest
Weakness and stiffness 2ndary to pain
Common examination signs in SAIS.
Neers impingement test
Hawkins test
Explain Neers impingement test
Arm is placed by the patient’s side
It should be fully internally rotated and then passively flex.
+ve = Pain in the anterolateral aspect of the shoulder.
Explain Hawkins test
Shoulder and elbow are flexed to 90 degrees
Examiner then stabilises the humerus and passively internally rotates the arm.
+ve = Anterolateral shoulder pain
Dx of SAIS
Muscular tear
Neurological pain
Frozen shoulder syndrome
Acromioclavicular pathology
Ix of SAIS
Diagnosis is clinical
Often confirmed by additional imaging like MRI
Findings on MRI
Formation of subacromial osteophytes and sclerosis
Subacromial bursitis
Humeral cystic changes
Narrowing of the subacromial space
Conservative management
Usually the mainstay treatment.
Analgesia by NSAIDs, physio (postural, stability, mobility, stretching and strength)
If not enough corticosteroid injection can be done into subacromial space.
