Shoulder Instability

Question 1

Risk factors for posterior shoulder dislocation?

Answer 1

glenoid retroversion
ligamentous laxity (beighton)
- common in linemen, weight lifters, overhead athletes

Question 2

what is the high risk position for posterior dislocation?

Answer 2

shoulder flexion, adduction, and internal rotation

Question 3

Lesions associated with posterior shoulder instability

Answer 3

• posterior band of IGHL avusion
• posterior bankart
• reverse Hill-Sachs
• posterior labral cyst
• posterior glenoid rim fx
• lesser tubersosity fx
• large capsular pouch

Question 4

Primary stabilizers of the posterior shoulder:

Answer 4

• posterior band of IGHL (internal rotation)
• subscapularis (restraint to external rotation, and posterior subluxation)
• SGHL (inferior translation of the adducted arm and external rotation, PRIMARY RESTRAINT IN FLEXION, ADDUCTION, IR)

Question 5

Posterior load and shift test

Answer 5

• neutral rotation arm, 40-60 deg abduction and forward flexion, load humeral head and apply anterior and posterior translating forces noting subluxation

Question 6

Jerk test

Answer 6

97% sensitive for posterior labral tear in combination with a Kim test

• arm at 90 deg abduction, internal rotation, elbow bent
• apply axial force along axis of humerus and adduct the arm to a forward-flexed position

Question 7

Acute management of a posterior dislocation?

Answer 7

• reduction and immobilization in external rotation 4-6 weeks
• then

Question 8

what is a kim lesion?

Answer 8

an incompletely stripped posterior capsulolabral complex

Question 9

if you over-retrovert a prosthesis, you risk:

Answer 9

anterior dislocation

Question 10

if you over-antevert a prosthesis, you risk:

Answer 10

posterior dislocation

Question 11

best way to manage a reverse hill-sachs lesion with locked posterior dislocation?

Answer 11

modified mclaughlin

• the lesser with the subscap is advanced into the bony defect on the anterior humeral head
• put it into the defect
• defect should be <40% of the articular surface

Question 12

What is the recurrent posterior instability rate in the young active population?

Answer 12

90%

Question 13

What patients deserve surgery following an anterior shoulder dislocation?

Answer 13

• male
• age <25
• competitive athlete
• contact sport

Question 14

how much anterior glenoid bone loss is acceptable without doing a coracoid transfer?

Answer 14

up to 20% can be tolerated, beyond that, do the Latarjet

- >20% loss significantly reduces the force required for redislocation

Question 15

MGHL function

Answer 15

provides anterior stability in up to 45 deg abduction and external rotation

Question 16

IGHL function

Answer 16

anterior band = main anterior restraint in abduction and max external rotation

inferior and posterior bands as well