•Commonest of all shoulder dislocation, accounting for 97 % of all shoulder dislocation
1.Subcoracoid (most common, 90%)
Mechanism of injury
•Most common cause is fall on out-streched hand with the limb in external rotation
•Stripping of the capsule from the inferior aspect of the humeral head
•Disruption of the glenohumeral ligaments & streching of the capsule enc
•Bankart lesion is an injury of the anterior (inferior) glenoid labrum
•Tearing of rotator cuff chiefly subscapularis & supraspinatus
•Displacing of biceps tendon from bicipital groove
•Severe stretching of the rotator muscles, chiefly subscapularis & supraspinatus
•Hill–Sachs fracture, is a cortical depression in the posterolateral head of the humerus. It results from forceful impaction of the humeral head against the anteroinferior glenoid rim
•History of fall & immediate disability is often present
•Pt. Holds the arm rigidly & avoids any movement
•Loss of contour of shoulder joint, replaced by flattening below the acromion
•Head is palpable below the coracoid or glenoid fossa
•Abduction & internal rotation are especially affected
•Distal neurovascular deficit may occur due to involvement of axillary artery & nerve
Special tests :
•BRYANT’S TEST :
The ant. Axillary fold of the affected side is at a lower level
Commonly, present in subcoracoid type
•CALLAWAY’S TEST :
Increased vertical circumference of the axilla
•DUGA’S TEST :
Pt. Is unable to touch hthe opposite shoulder with his hand
•HAMILTON’S RULER TEST :
Normally a ruler cannot touch the acromion & the lateral epicondyle simultaneously, but is possible in ant. Shoulder dislocations
•REGIMENT BADGE SIGN :
Loss of sensation over the upper lateral aspect of the arm
RADIOGRAHY PLAIN RADIOGRAPHS
i) Subacromial type of posterior dislocation is often missed.
Signs to make out dislocation in this view are :
•Absence of normal elliptical overlap shadow
•loss of normal half-moon overlap sign, in which the glenoid fossa appears vacant due to the lateral displacement of the humeral head
•Loss of profile of the neck of the humerus.
•Void in the inferior or superior third of the glenoid fossa.
•ii) Transthoracic lateral view :
•iii) Axillary lateral x-ray view : It is useful to detect size of head compression fracture, glenoid or lesser tuberosity fracture
1. Westpoint - axillary lateral view useful to detect
fracture of the anteroinferior glenoid rim.
2.Apical oblique view – useful to
detect defects of the anterior glenoid rim and
3. Special views to detect humeral head defects
•Didee view -anterior glenoid lip fracture.
•Hillsachs view- to detect Hillsach lesion.
Special studies :
•CT -Scan: Helps detect glenoid rim and bumeral head defects.
•MRI: Helps detect lesions of cuff, capsule and labrum. The sensitivity and specificity of glenohumeral instability were 88% and 93% respectively.
•Arthroscopic examination under GA: Excellent technique for confirming presence of shoulder instability and detecting pathological lesions.
Closed reduction :
•Should be reduced quickly & under short GA
•Early reduction- Eliminates stretch and compression over neurovascular structure, minimizes muscles spasm and prevents progressive enlargement of humeral head defect in locked dislocation.
a.Hippocratic technique :
operator places his foot in the armpit of the affected side of the patient, holds the patient's hand, and pulls toward the him
b.Milch's technique :
With the patient supine, the arm is abducted and externally rotated, and the thumb is used to gently push the head of the humerus back in place.
c. Modified Stimson 's technique :
The patient is placed prone on the edge of the examining table while downward traction is gently applied.
•Appropriate weights are taped to the wrist(Five pounds is usually sufficient)
• When using this technique, one should be patient since it may take 15 to 20 minutes for the reduction to occur.
d. Kocher's leverage technique:
•Preliminary stretching in the line of the long axis of the shaft of the humerus.
•While maintaining steady traction, the arm is rotated externally and very gently until 80° of extenal rotation is achieved.
•With the arm, the elbow is brought forward to a point near the midline of the trunk.
•The arm is rotated internally and the hand is placed on the opposite shoulder.
e. Traction - counteraction method :
•Position – supine position, a sheet is folded to form a 5-inch swathe, & is used as the countertraction to stabilize
•Very gentle traction is applied to the involved arm in line with the deformity, and the traction is increased very gradually
•Slight internal and external rotation is used to disengage.
1.Irreducible anterior dislocations due to soft tissue interposition.
2. Recurrent dislocations
•Surgery is considered if apprehension or instability repeatedly compromises shoulder comfort/function in spite of a reasonable trial of internal and external rotator strengthening exercises.
•Atraumatic shoulder instability
3. Displaced fracture of greater tuberosity (ORIF is done if the fragment remains displaced >5mm after reduction) and repair of the attendant split in the tendon of rotator cuff.
4. Glenoid rim fractures - ORIF is considered for fragments involving 25% of anterior glenoid with displacement of 20mm or more.
5. Pt. with occupations which require complete and absolute stability before being able to return to work.
COMPLICATIONS associated with Shoulder Dislocation
1.Bone injuries :Compression fracture of humeral head, fracture of anterior glenoid lip, greater tuberosity, acromion and coracoid process.
2.Soft tissue injuries : Rotator cuff tears (more common in older people and present as pain or weakness on external rotation or abduction).
3.Vascular injuries : More in elderly patients, axillary artery (second part is most commonly involved) and its branches, vein are most commonly involved. Injury can occur at dislocation or reduction.
4.Neural injuries : Most commonly involved nerve is axillary nerve. The head displaces the subscapularis tendon and muscle forward, creating traction and direct pressure on the nerve.