The Shoulder Flashcards
What are the four joints of the shoulder?
- Glenohumeral
- Acromioclavicular
- Sternoclavicular
- Scapulothoracic (functional?)
List 3 factors that cause shoulder instability
- Shallow glenoid
- Loose capsule
- Ligamentous laxity
Which is the most commonly dislocated joint in the body and why?
GH joint - stability is sacrificed for motion
List three complications of a shoulder dislocation - which is the most common?
- Rotator cuff/capsular tear
- Injury to axillary nerve/artery, brachial plexus
- Recurrent/unreduced dislocation (most common)
What is the mechanism of injury in an anterior shoulder dislocation? (2)
- Abducted arm is ER/hyperextended
2. Blow to posterior shoulder
What signs are/could be present in an anterior shoulder dislocation? (5)
- Inability to IR
- Positive apprehension test
- Positive relocation test
- Positive sulcus sign
- Neurovascular findings (axillary nerve - sensory patch over deltoid and deltoid contraction and musculocutaneous nerve - sensory patch on lateral forearm and biceps contraction)
What is a positive apprehension test?
Patient looks apprehensive with gentle shoulder abduction and external rotation to 90 degrees since humeral head is pushed anteriorly and recreates feeling of anterior dislocation (possible sign in anterior shoulder dislocation)
What is a positive relocation test?
Posteriorly directed force applied during the apprehension test relieves apprehension since anterior subluxation is prevented (possible sign in anterior shoulder dislocation)
What is the positive sulcus sign?
Presence of a subacromial indentation with distal traction on humerus indicates inferior shoulder instability (possible sign in anterior shoulder dislocation)
How would you investigate an anterior shoulder dislocation?
X-ray - AP, trans-scapular, axillary
List 4 radiographic findings would you find in an anterior shoulder dislocation
- X-ray axillary view: humeral head is anterior
- X-ray transcapular/scapular ‘Y’ view: humeral head is anterior to the Mercedes-Benz sign
- +/- Hill-Sachs lesion: compression fracture of posterior humeral head due to forceful impaction of anterioly dislocated humeral head against the glenoid rim
- +/- bony Bankart lesion: avulsion of the anterior glenoid labrum (with attached bone fragments)
What is a Hill-Sachs lesion?
compression fracture of posterior humeral head due to forceful impaction of anterioly dislocated humeral head against the glenoid rim
What is a Bankart lesion?
avulsion of the anterior glenoid labrum (with attached bone fragments)
How is an anterior shoulder dislocation managed?(4)
- Closed reduction with IV sedation and muscle relaxation
- Obtain post-reduction X-rays
- Check post-reduction NVS
- Sling x 3 weeks (avoid abduction and external rotation) followed by shoulder rehabilitation
What is the difference between joint laxity and joint instability?
Joint laxity - degree of translation in the GH joint which falls within a physiological range and which is asymptomatic
Instability - abnormal symptomatic motion - pain, subluxation or dislocation
What is the mechanism of injury in a posterior shoulder dislocation? (4)
- Adducted, IR, flexed arm
- FOOSH
- 3 Es (epileptic seizure, alcohol (EtOH), electrocution)
- Blow to anterior shoulder
Which movement is blocked in a posterior shoulder dislocation?
ER
What radiographic findings will be/could be seen in a posterior shoulder dislocation? (5)
- AP view: partial vacancy of glenoid fossa (vacant glenoid sign), and >6 mm space between anterior glenoid rim and humeral head (positive rim sign), humeral head may resemble a lightbulb due to internal rotation (lightbulb sign
- axillary view: humeral head is posterior
- Trans-scapular view: humeral head is posterior to centre of Mercedes-Benz sign
- +/- reverse Hill-Sachs lesion: divot in anterior humeral head
- +/- reverse bony Bankart lesion - avulsion of the posterior glenoid labrum from the bony glenoid rim
Where do the rotator cuff muscles attach?
Supraspinatus, infrapsinatus, teres minor attach to greater tuberosity of humerus
Subscapularis attaches to lesser tuberosity of humerus
What innervates the rotator cuff muscles?
Supraspinatus and infraspinatus - suprascapular nerve
Teres minor - axillary nerve
Subscapularis - sub scapular nerve
Which rotator cuff muscle is responsible for abduction?
Supraspinatus
Which special test can be used to detect a supraspinatus tear?
Jobe’s test (empty can) - weakness with active resistance suggests supraspinatus tear
Which rotator cuff muscles are responsible for ER?
Infraspinatus and teres minor
Which rotator cuff muscle is responsible for internal rotation/adduction?
Subscapularis
Which special test(s) can be used to test subscapularis?
Lift-off test (hand behind back) - inability to to actively lift hand away from back suggests a subscapularis tear
Can use belly press test
Which part of the clavicle is most commonly fractured?
Middle (80%) followed by lateral (15%) then proximal (5%)
List three ways in which a clavicle fracture can occur.
- Fall on shoulder (87%)
- Direct trauma to clavicle (7%)
- FOOSH (6%)
What are the two main ligaments that attach the clavicle to the scapula?
AC and CC ligaments
What are the potential complications of a severe acromioclaviculuar joint dislocation?
Pneumothorax or pulmonary contusion
What are the features of the pain found in adhesive capsulitis?
Gradual onset (weeks to months) of diffuse shoulder pain with decreased active and passive ROM
pain usually worse at night, often prevents sleeping on affected side
Increased stiffness as pain subsides (continuing even after pain has gone)
What are the X-ray findings in adhesive capsulitis?
May be normal - main value is to exclude other causes of a painful, stiff shoulder
How is frozen shoulder managed? (3)
- Physiotherapy - active and passive ROM
- NSAIDS and steroid injections
- Arthroscopy for debridement/decompression
What is the clinical appearance of a dislocated GH joint vs a subluxed/dislocated AC joint?
Dislocated GH joint - characteristic ‘squaring off’ of shoulder, with depression in skin noted
Subluxed/dislocated AC joint - ‘step’ deformity or bump in shoulder with the tip of collar bone sticking up
