Shoulder Flashcards
Shoulder dislocation investigations
- anterior dislocation X-rays: AP, trans-scapular, axillary views
- posterior dislocation X-rays: AP, trans-scapular, axillary; or CT scan
What joints make up the shoulder
glenohumeral,
AC,
sternoclavicular (SC),
scapulothoracic
Anterior shoulder dislocation mechanism
Abducted arm is externally rotated/hyperextended, or blow to posterior shoulder
Involuntary, usually traumatic; voluntary, atraumatic
Anterior shoulder dislocation clinical features
Pain, arm slightly abducted and externally rotated with inability to internally rotate
“Squared off” shoulder
Positive apprehension test: patient looks apprehensive with gentle shoulder abduction and external rotation to 90º as humeral head is pushed anteriorly and recreates feeling of anterior dislocation
Positive relocation test: a posteriorly directed force applied during the apprehension test relieves apprehension since anterior subluxation is prevented
Positive sulcus sign: presence of subacromial indentation with distal traction on humerus indicates inferior shoulder instability
Axillary nerve: sensory patch over deltoid and deltoid contraction
Musculocutaneous nerve: sensory patch on lateral forearm and biceps contraction
Anterior shoulder dislocation radiographic findings
Axillary View -Humeral head is anterior
Trans-scapular ‘Y’ View -
Humeral head is anterior to the centre of the “Mercedes-Benz”sign
AP View - Sub coracoid lie of the humeral head is most common
Hill-Sachs and Bony Bankart Lesions -
± Hill-Sachs lesion: compression fracture of posterior humeral head due to forceful impaction of an anteriorly dislocated humeral head against the glenoid rim
± bony Bankart lesion: avulsion of the anterior glenoid labrum (with attached bone fragments) from the glenoid rim
Anterior shoulder dislocation treatment
Closed reduction with IV sedation and muscle relaxation
Traction-countertraction: assistant stabilizes torso with a folded sheet wrapped across the chest while the surgeon applies gentle steady traction
Stimson: while patient lies prone with arm hanging over table edge, hang a 5 lb weight on wrist for 15-20 min
Hippocratic method: place heel into patient’s axilla and apply traction to arm
Cunningham’s method: low risk, low pain; if not successful try above methods
Obtain post-reduction x-rays
Check post-reduction NVS
Sling x 3 wk (avoid abduction and external rotation), followed by shoulder rehabilitation (dynamic stabilizer strengthening)
Posterior shoulder dislocation mechanism
Adducted, internally rotated, flexed arm
FOOSH
3 Es (epileptic seizure, EtOH, electrocution)
Blow to anterior shoulder
Posterior shoulder dislocation clinical features
Pain, arm is held in adduction and internal rotation; external rotation is blocked
Anterior shoulder flattening, prominent coracoid, palpable mass posterior to shoulder
Positive posterior apprehension (“jerk”) test: with patient supine flex elbow 90° and adduct, internally rotate the arm while applying a posterior force to the shoulder; patient will “jerk” back with the sensation of subluxation
Note: the posterior apprehension test is used to test for recurrent posterior instability, NOT for acute injury
Full NV exam as per anterior shoulder dislocation
Posterior shoulder dislocation radiographic findings
Axillary view - Humeral head is posterior
Trans-scapular ‘Y’ View - Humeral head is posterior to centre of “Mercedes-Benz” sign
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)
± reverse Hill-Sachs lesion (75% of cases): divot in anterior humeral head
± reverse bony Bankart lesion: avulsion of the posterior glenoid labrum from the bony glenoid rim
Posterior shoulder dislocation treatment
Closed reduction with sedation and muscle relaxation
Inferior traction on a flexed elbow with pressure on the back of the humeral head
Obtain post-reduction x-rays
Check post reduction NVS
Sling in abduction and external rotation x 3 wk, followed by shoulder rehabilitation (dynamic stabilizer strengthening)
Shoulder disloccation prognosis
• recurrence rate depends on age of first dislocation
• <20 yr = 65-95%;
20 40 yr = 60-70%;
>40 yr = 2-4%
Shoulder dislocation specific complications
- rotator cuff or capsular or labral tear (Bankart/SLAP lesion), shoulder stiffness
- injury to axillary nerve/artery, brachial plexus
- recurrent/unreduced dislocation (most common complication)
Shoulder passive ROM
Abduction 180o
Adduction 45o
Flexion 180o
Extension 45o
Internal rotation - level of T4
External rotation 40-45o
Factors causing shoulder instability
- Shallow glenoid
- Loose capsule
- Ligamentous laxity
Frequency of dislocation types
- Anterior shoulder > Posterior shoulder
- Posterior hip > Anterior hip The glenohumeral joint is the most commonly dislocated joint in the body since stability is sacrificed for motion
Supraspinatus muscle attachments, nerve supply and function
Attachment
proximal - scapula
distal - greater tuberosity of humerus
Nerve supply - suprascapular nerve
Function - abduction
Infraspinatus muscle attachments, nerve supply and function
Attachment
proximal - scapula
distal - greater tuberosity of humerus
Nerve supply - suprascapular nerve
Function - external rotation
Teres minor muscle attachments, nerve supply and function
Attachment
proximal - scapula
distal - greater tuberosity of humerus
Nerve supply - axillary nerve
Function - external rotation
Subscapularis muscle attachments, nerve supply and function
Attachment
proximal - scapula
distal - lesser tuberosity of humerus
Nerve supply - subscapular nerve
Function - internal rotation and adduction
Spectrum of rotator cuff disease
Impingement
Tendonitis
Micro or macro tears
Rotator cuff disease etiology
• anything that leads to a narrow subacromial space
• most commonly, a relative imbalance of rotator cuff and larger shoulder muscles, allowing for superior translation and subsequent wear of the rotator cuff muscle tendons
■ glenohumeral muscle weakness leading to abnormal motion of humeral head
■ scapular muscle weakness leading to abnormal motion of acromion
• acromial abnormalities, such as congenital narrow space or osteophyte formation or Type III acromion morphology
- outlet/subacromial impingement: “painful arc syndrome”, compression of rotator cuff tendons (primarily supraspinatus) and subacromial bursa between the head of the humerus and the undersurface of acromion, AC joint, and CA ligament
- bursitis and tendonitis
- rotator cuff thinning and tear if left untreated
Rotator cuff disease clinical features
- insidious onset, but may present as an acute exacerbation of chronic disease, night pain, and difficulty sleeping on affected side
- pain worse with active motion (especially overhead); passive movement generally permitted
- weakness and loss of ROM, especially between 90°-130° (e.g. trouble with overhead activities)
- tenderness to palpation over greater tuberosity
• rule out
bicep tendinosis: Speed test;
SLAP lesion: O’Brien’s test
Rotator cuff disease investigations
- X-ray: AP view may show high riding humerus relative to glenoid, indicating large tear, evidence of chronic tendonitis
- MRI: coronal/sagittal, oblique and axial orientations are useful for assessing full/partial tears and tendinopathy ± arthrogram: geyser sign (injected dye leaks out of joint through rotator cuff tear)
- arthrogram: can assess full thickness tears, difficult to assess partial tears
Rotator cuff disease treatment
• non-operative
■ for mild (“wear”) or moderate (“tear”) cases
■ physiotherapy, NSAIDs ± steroid injection
• operative
■ indication: severe (“repair”)
■ impingement that is refractory to 2-3 mo physiotherapy and 1-2 corticosteroid injections
■ arthroscopic or open surgical repair (i.e acromioplasty, rotator cuff repair)
