Clinical conditions of the shoulder Flashcards
What are the majority of shoulder dislocations? What position is the arm held in?
Anterior
(anteroinferiorly = as inf. aspect weak)
Ext. rotation, abduction
What is the injury mechanism for an anterior shoulder dislocation?
Arm in abuction + ext. rotation (hand behind head) + arm forced post.
Direct blow to post. shoulder
What is a Bankart lesion/labral tear?
Force of humeral head dislocating = tear part of glenoid labrum
What is a Hill-Sachs lesion?
Indentation fracture in posterolateral humeral head as post. humeral head jammed against ant. lip of glenoid fossa
Due to ant. dislocation + tone of infraspinatus + teres minor
What is the injury mechanism for a posterior dislocation?
Violent muscle contraction from epileptic seizure/lightning strike
Blow to ant. shoulder
Arm flexed across body + pushed post.
What position is the patient in with a post. dislocation?
Internally rotated, adducted arm
Flattening/squaring of shoulder, prominent coracoid process
Can’t externally rotate to anatomical position
(rotator cuff tears, fractures, Hill-Sachs lesions)
What is the mechanism of injury for an inferior dislocation? What are the associated injuries?
Forceful traction when arm hyperabducted over head
Rotator cuff tears, nerve/blood vessel injury
What are the 5 common complications of shoulder dislocation?
Recurrent dislocation (damage to stabilising tissue, glenoid labrum + increased OA risk as humeral head damage)
Axillary artery damage (haematoma, absent pulses, cool limb)
Axillary nerve injury (supplies deltoid + overlying skin = regimental badge area)
Fractures (traumatic injury/1st dislocation, over 40)
Rotator cuff muscle tears (older people)
Where are the majority of clavicle fractures? What is the mechanism of injury and how are they treated?
Middle 1/3rd (mid-clavicular)
Fall onto shoulder or FOOSH
Treat conservatively (or surgery = complete displacement, severe displacement with puncture, open fracture, floating shoulder = clavicle fracture + ipsilateral glenoid neck fracture)
What happens to the position of the arm and clavicular fragments in a displaced mid-clavicular fracture?
Sternocleiodomastoid muscle elevates medial segment
Shoulder drops as trapezius can’t hold lateral segment up
Adduction by pec. major
What nerves may be damaged by a clavicle fracture?
Suprascapular nerve
Supraclavicular nerve = ant. upper chest paraesthesia (C3 + C4)
What is the most common rotator cuff tear?
Supraspinatus TENDON, beneath coracoacromial arch
Why are most rotator cuff tears chronic?
Extended use with poor biomechanics/muscular imbalance/age-related degeneration (blood supply to muscles decrease = impaired ability to repair minor injuries = degenerative-microtrauma model with inflammatory cells + ox. stress = tenocyte apoptosis)
What is the most common presentation of a rotator cuff tear?
Anterolateral shoulder pain, radiates down arm
Pain when lean on elbow + push down
Shoulder pain when reaching forward
Weakness of shoulder abduction
What is impingement syndrome?
Supraspinatus tendon impinges on coraco-acromial arch = irritation/inflammation
From thickening of ligament/inflammation of tendon/subacromial osteophytes = narrows space
What is the pain in impingement syndrome?
Shoulder abducted/flexed = space narrows
Dull pain, grinding with shoulder movement
Painful arc between 60-120 degrees abduction
What is calcific supraspinatus tendinopathy? What are the symptoms?
Macroscopic deposits of hydroxyapatite in supraspinatus tendon
Pain with shoulder abduction/flexing arm + mechanical symptoms (stiffness, reduced range shoulder movement)
What causes calcific supraspinatus tendinopathy?
Regional hypoxia = tenocytes to chondrocytes = cartilage then calcium deposits
OR
Ectopic bone formation from metaplasia of MSCs to osteogenic cells
When is the most pain during calcific supraspinatus tendinopathy?
Reabsorption by phagocytes (look like toothpaste = cloudy on x-ray)
What is adhesive capsulitis?
Frozen shoulder
Capsule of glenohumeral joint inflamed + stiff = chronic pain (worse @ night, cold weather)
What are some risk factors for frozen shoulder?
Autoimmune
Female, diabetes mellitus, thyroid disease, CVD
How is frozen shoulder treated?
Physio, analgesia, anti-inflammatory
Manipulation under analgesia = break up scar tissue to restore range of motion
What joint does shoulder OA most commonly affect? How is it treated?
Acromioclavicular joint
(Same as OA for others)
Arthroscopy = remove loose pieces damaged cartilage
Hemiarthroplasty (replacement of humeral head)/total shoulder replacement
How does a fractured surgical neck of the humerus occur?
What neurovascular structures are at risk?
Blunt trauma to shoulder or FOOSH
Axillary nerve, post. circumflex artery
What is the popeye sign caused by?
Rupture of biceps tendon
Little weakness in upper limb due to action of brachialis/supinator muscles
