Glenohumeral Dislocation/Subluxation Lowe

Question 1

What is Glenohumeral Dislocation/Subluxation

Answer 1

-dislocated more than any other joint; can be completely forced out of the joint capsule, partially translated or forced out with an immediate return to position

Question 2

Characteristics:

Answer 2

bony contact surface between the head of the humerus and the glenoid fossa is minimal because the humeral head is larger and the glenoid fossa is relatively flat; the socket is shallow (compared with iliofemoral joint) but deepened by the glenoid labrum surrounding the rim of the glenoid fossa; ligaments, labrum and joint capsule maintain stability of the humerus

Glenohumeral dislocation: head of humerus is forced out of glenoid fossa and stays out

Subluxation: joint is partially dislocated and humeral head does not fully move out of the fossa or when humeral head moves out of the fossa and then returns

-can result from chronic instability or traumatic injury, initially result from traumatic forces which lead to instability and repeated dislocation/subluxation

-if instability is present, strong forces are not needed to dislocate; recurrent in athletes or adolescents; instability involves mild laxity and hypermobility to severe dislocation; can create disability and physical impairment; can occur in a single direction (ex. anterior instability) or several directions (multi-directional instability)

-anterior instability is most common

-can result from repetitive shoulder motions that place tensile stress on ligaments or joint capsule (repeated throwing); instability can lead to subluxation, impingement, rotator cuff pathology, eventual dislocation

-repeated subluxations/dislocations can be precursors to tendinosis, arthritis, nerve injuries of brachial plexus, fractures, bone spurs or labral damage

-systemic diseases (Ehlers-Danlos or Marfan syndromes) can cause ligament laxity

-laxity allows humeral head to passively translate (instead of roll) within glenoid fossa; susceptible to sublux/dislocation

-direction of sublux/dislocation is related to forces applied to GH joint; largest number are anterior and occur with abduction and lateral rotation of humerus (likely to cause a Bankart lesion: avulsion of GH joint capsule and labrum from inferior glenoid rim)

-subluxations not as painful as dislocations but level of pain depends on status of humeral head; may or may not be pain if humeral head returns to position after being forced out; may be painful if partially dislocated due to pressure on edge of glenoid labrum

• refer to physician if suspect dislocation for proper reduction to prevent damage to neurovascular structures; refer subluxation for proper level of injury diagnosis

-patients will report a movement or impact that caused sudden pain and significant decrease in ROM if subluxation; muscle spasm immediately limits ROM; if joint moved back into position, pain gradually subsides, spasm may continue

-patient reports sharp, immediate pain with complete inability to use arm if dislocation; arm held close to side to prevent movement; muscle spasm remains after reduction for longer period

Question 3

History:

Answer 3

sudden force to shoulder that causes severe pain, followed by inability to move arm; identify mechanics of injury to determine motions that produce sublux/dislocations (abduction and lateral rotation); hold arm in adducted and internally rotated position to avoid pain; ask about level of pain, may report self-reducing dislocated joint (if recurring); ask about history of acute trauma, systemic conditions (ligament laxity) or repetitive activities (instability)

Question 4

Observation:

Answer 4

holds arm close to body; sulcus (indentation) may be visible below edge of acromion process; signs of inflammation (red, edema); motion not possible with complete dislocation; apprehension with subluxation when get close to position(s) of vulnerability (abduction/ lateral rotation); proprioceptors recognize the position

Question 5

Palpation:

Answer 5

tenderness around shoulder joint due to muscle spasm and inflammation; sulcus identifiable as soft spot and indentation; may palpate displacement of humeral head

Question 6

Range of Motion and Resistance Testing

Answer 6

AROM: do not attempt if presenting with signs of dislocation; with subluxation, movement may be
possible in all directions, limited by pain/ apprehension

PROM: do not attempt if presenting with signs of dislocation; with subluxation, use caution and slow
application and watch for apprehension

MRT: muscle contraction not functional if dislocation; weak contractions if subluxation due to neurological inhibition or pain avoidance; pain and/or weakness in subscapularis if sublux/ dislocation is severe (often torn in anterior dislocation)

Question 7

Differential Evaluation:

Answer 7

glenoid labrum damage, severe rotator cuff tears, clavicular fracture, subacromial impingement, neurovascular damage, biceps tendon subluxation

Question 8

Suggestions for Treatment:

Answer 8

proper identification of a sublux/dislocation is important, refer to physician; surgery may be necessary; general massage after reduction to alleviate reflexive muscle spasm in shoulder