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
