Conditions Of The Shoulder Flashcards
What is a fracture of the surgical neck of the humerus usually from? 1️⃣
- blunt trauma to shoulder
- FOOSH
What key neurovascular structures are at risk?1️⃣
- axillary nerve
- posterior humeral circumflex artery
What will axillary nerve damage result in? 1️⃣
- paralysis of deltoid and teres minor muscles
- difficultly performing abduction of the affected limb
Nerve also innervates skin over deltoid insertion so sensation in this region will be impaired
Where may the long head of the biceps brachii rupture? 2️⃣
Near to its scapular origin
Most common,y I’m patients >50, following quite minimal trauma
In weightlifters, the distal tendon of the biceps sometimes snaps near to its insertion instead
What is a characteristic sign of a ruptured biceps tendon? 2️⃣
‘Popeye sign’
Flexion of the arm at elbow produces a firm lump in the lower part of the arm - this is the unopposed contracted muscle belly of the biceps
What does the patient typically experience?2️⃣
-hear something %’snap’ in the shoulder whilst lifting
-not notice much weakness in the upper limb because the action of the brachialis (flexion) and supinate (supination) muscles is intact
(So management is mainly conservative)
How do dislocated shoulders typically look? 3️⃣
- visibly deformed
- may be visible swelling &/or bruising around shoulder
- restricted movement of shoulder
Why are 90-95% of shoulder dislocations anterior? 3️⃣
- glenoid fossa is shallow
- joint strengthened on its superior, anterior and posterior aspects but weak at its inferior aspect
- head of humerus therefore usually dislocated anteroinferiorly, but then often displaces in an anterior direction (subcoracoid location =60% cases) due to pull of muscles and disruption of the anterior capsule and ligaments
-alternatively, head of humerus may come to lie antero-inferior to the to the glenoid (subglenoid location = 30% cases)
Describe the position of the arm in an anterior shoulder dislocation 3️⃣
- externally rotated
- slightly abducted
Describe the mechanism of the anterior dislocation of the shoulder 3️⃣
- arm abducted and externally rotated e.g. ‘hand behind head’
- unexpected small injury forces arm a little further posteriorly
- shoulder pushed into an extreme position, such that the humeral head dislocates antero-inferiorly from the glenoid
An alternative mechanism is a direct blow to the posterior shoulder
What is a Bankart lesion or labral tear? 3️⃣
Partial tear of the glenoid labrum off the glenoid cavity
Caused by the force of the humeral head popping out of the socket
Sometimes a small piece of bone can be torn off with it
What is a Hill-Sachs lesion and what causes it? 3️⃣
-a dent (indentation fracture) in the posterolateral humeral head
Cause:
-when humeral head dislocated anteriorly, the tone of the infraspinatus and teres minor mean that the posterior aspect of the humeral head becomes jammed against the anterior lip of the glenoid fossa
*increase chance of secondary osteoarthritis in the shoulder joint
When are Hill-Sachs lesions seen? 3️⃣
50% of anterior shoulder dislocations in <40yr olds
80% of recurrent dislocations
Why do posterior shoulder dislocations tend to occur? 3️⃣
When there are violent muscle contractions
- epileptic seizure
- electrocution
- lightning strike
When there is a blow to the anterior shoulder
When arm is flexed across body and pushed posteriorly
How do patients with posterior shoulder dislocations present? 3️⃣
- arm internally rotated and adducted
- demonstrate flattening/squaring of shoulder with a prominent coracoid process
- arm cannot be externally rotated into the anatomical position
How does a posterior shoulder dislocation look on an X-ray? 3️⃣
- can be easily missed as it looks ‘in joint’
- since arm is internally rotated, the projection of the humeral head on the X-ray film changes to a more rounded shape: the ‘lightbulb’ sign
- glenohumeral distance is also increased
What view is also useful for detecting shoulder dislocations on an X-ray? 3️⃣
- scapular or ‘Y’ view
- head of humerus should be directly in line with the glenoid fossa i.e at the bifurcation of the Y
What injuries are commonly associated with posterior shoulder dislocations? 3️⃣
- fractures
- rotator cuff tears
- Hill-sachs lesion
How do inferior dislocations of the shoulder occur? 3️⃣
(Head of humerus sits inferior to the glenoid)
-mechanism is forceful traction on the arm when it is fully extended over the head, as may occur when grasping an object above the head to break a fall e.g. hyperabduction injury
What injuries are associated with an inferior shoulder dislocation? 3️⃣
- damage to nerves
- rotator cuff tears
- injury to blood vessels
What is the most common complication of shoulder dislocation? 3️⃣
-recurrent dislocation
Due to damage to the stabilising tissues surrounding the shoulder
- chance of further dislocation depends on age and activity levels
- each dislocation results in further damage to humeral head and glenoid, therefore increasing the risK of osteoarthritis
Which patients are more likely to have axillary artery damage as a result of shoulder dislocation? 3️⃣
Older age groups
Since their blood vessels are less elastic
May also have a haematoma, absent pulses &/or a cool limb
What nerve injury is common in shoulder dislocations? 3️⃣
Axillary nerve injury
-wraps around humeral neck and supplies deltoid muscles and skin overlying deltoid insertion (regimental badge area)
- full recovery usually made as symptoms resolved when shoulder reduced
- less commonly, should dislocation may damage the cord of the brachial plexus or musculocutaneous nerve
When do significant fractures occur due to shoulder dislocations? 3️⃣
- when there is a traumatic mechanism of injury
- first time dislocation
- person >40 years old
