Shoulder Instability

Question 1

What increases the recurrence rate in patients with TUBS?

Answer 1

▪ have a high recurrence rate that correlates with age at dislocation

up to 80-90% in teenagers (90% chance for recurrence in age <20)

Question 2

What are the 4 Associated injuries with TUBS?

Answer 2

1- labral & cartilage injuries

Bankart lesion

is an avulsion of the anterior labrum and anterior band of the IGHL from the anterior inferior glenoid.

is present in 80-90% of patients with TUBS

Humeral avulsion of the glenohumeral ligament (HAGL)

occurs in patients slightly older than those with Bankart lesions

associated with a higher recurrence rate if not recognized and repaired

an indication for possible open surgical repair

Glenoid labral articular defect (GLAD)

is a sheared off portion of articular cartilage along with the labrum

Anterior labral periosteal sleeve avulsion (ALPSA)

can cause torn labrum to heal medially along the medial glenoid neck

associated with higher failure rates following arthroscopic repair

2- Fractures & bone defects

Bony Bankart lesion

is a fracture of the anterior inferior glenoid

present in up to 49% of patients with recurrent dislocations

higher risk of failure of arthroscopic treatment if not addressed

defect >20-25% is considered “critical bone loss” and is biomechanically highly unstable

stability cannot be restored with soft tissue stabilization alone (unacceptable >2/3 failure rate)

require bony procedure to restore bone loss (Latarjet-Bristow, other sources of autograft or allograft)

recent studies suggest critical bone loss may be as low as 13.5%

Hill Sachs defect

is a chondral impaction injury in the posterosuperior humeral head secondary to contact with the glenoid rim.

is present in 80% of traumatic dislocations and 25% of traumatic subluxations

is not clinically significant unless it engages the glenoid

Greater tuberosity fracture

is associated with anterior dislocation in patients > 50 years of age

Lesser tuberosity fracture

is associated with posterior dislocations

3- Nerve injuries:Axillary nerve injury

is most often a transient neurapraxia of the axillary nerve

present in up to 5% of patients

4- Rotator cuff tears

30% of TUBS patients > 40 years of age

80% of TUBS patients > 60 years of age

Question 3

What is the Antero-posterior Translation Grading Scheme

Answer 3

Grade 0: Normal glenohumeral translation

Grade 1+: Humeral head translation up to glenoid rim

Grade 2+: Humeral head translation over glenoid rim with spontaneous reduction once force withdrawn

Grade 3+: Humeral head translation over glenoid rim with locking

Question 4

Sulcus Test Grading Scheme

Answer 4

Grade 1: Acromiohumeral interval <1cm

Grade 2: Acromiohumeral interval 1-2cm

Grade 3: Acromiohumeral interval >2cm

Question 5

What is the ISIS score?

Answer 5

Question 6

What to look for on physical exam for TUBS?

Answer 6

Load and shift

Grade I - increased translation, no subluxation

Grade II - subluxation of humeral head to, but not over, glenoid rim

Grade III - dislocation of humeral head over glenoid rim

apprehension sign

patient supine with arm in 90/90 position

positive sign in mid-ranges of abduction is highly suggestive of concomitant glenoid bone loss

relocation sign

decrease in apprehension with anterior force applied on shoulder

sulcus sign

tested with patient’s arm at side

generalized ligamentous laxity

assess via Beighton’s criteria

shoulder specific laxity defined as

Hyper-external rotation at side > 85 degrees

Hyperabduction > 120 degrees (Gagey’s maneuver)

OR > 2+ load shift in 2 or more planes (anterior, posterior, inferior)

Question 7

5 Risk factors for re-dislocation?

Answer 7

1. age < 20 (highest risk)
2. male
3. contact sports
4. Hyper-laxity
5. Glenoid bone loss >20-25%

Question 8

Any benefits for immobilization of the shoulder > 1 week for TUBS?

Answer 8

studies have not shown any benefit of immobilization > 1 week for decreasing recurrence rates

Question 9

Indications for open Bankart repair?

Answer 9

• Bankart lesion with glenoid bone loss < 20-25%
• revision stabilization following failed arthroscopic Bankart repair without glenoid bone loss >20%
• humeral avulsion of the glenohumeral ligament (HAGL); can also be performed arthroscopically but is technically challenging

Question 10

Indications for Latarjet procedure?

Answer 10

1. Chronic bony deficiencies with >20-25% glenoid deficiency (inverted pear deformity to glenoid)
2. transfer of coracoid bone with attached conjoined tendon and CA ligament
3. Latarjet procedure performed more commonly than Bristow
4. Latarjet triple effect = bony (increases glenoid track), sling (conjoined tendon on top of subscapularis), capsule reconstruction (CA ligament)

Question 11

2 Surgical options for >20-25% glenoid deficiency ?

Answer 11

1. Latarjet

2. Autograft (tri-cortical iliac crest) or allograft (iliac crest or distal tibia) for glenoid bone loss

Question 12

Indications for Remplissage technique

Answer 12

• Engaging large (>25-40%) Hill-Sachs defect
• “off-track” Hill-Sachs lesions with <20-25% glenoid bone loss

Question 13

Minimal number of anchors for Bankart labral repair?

Answer 13

≥ 3 anchors

Question 14

How to avoid axillary nerve injury during open bankart repair?

Answer 14

avoid by abduction and ER of arm during procedure

Question 15

What is the most common nerve injury seen in latarjet procedure and how to treat it?

Answer 15

▪ majority are traction or contusion neuropraxias and resolve spontaneously

treat with observation for 3-6 weeks; delayed EMG if deficits persist

musculocutaneous nerve is most common

occurs during instrumentation around the conjoint tendon

axillary nerve also at risk

occurs during graft fixation

Question 16

What are some risk factors for recurrence after surgery of TUBS?

Answer 16

• unrecognized glenoid bone loss (especially with glenoid bone loss >20-25%)
• can be due to poor surgical technique (ie, < 3 suture anchors)
• increased risk with preoperative risk factors including age < 20, male sex, contact/collision sport, ligamentous laxity, and unrecognized glenoid and/or humeral head bone loss (critical bone loss or “off-track” lesion)
• medical management should be exhausted prior to surgery in patients with seizures, as there is a high recurrence risk even when bony augmentation techniques are used
• unrecognized pan-labral tear

Question 17

8 complications after Bankart Repair?

Answer 17

1. Recurrence
2. Shoulder Pain
3. Nerve injury
4. Stiffness
5. Infection
6. Graft Lysis
7. Hardware complications
8. Chondrolysis

Question 18

What are Beighton criteria’s

Answer 18

Question 19

ON-Track and OFF-Track lesions

Answer 19

Glenoid track = area of contact between the humeral head and glenoid and is defined as ~83% of glenoid width

A Hill-Sachs defect that is smaller than the track (“on-track”) will maintain contact and is at lower risk of engagement and instability. Conversely, a Hill-Sachs defect that is larger than the glenoid track (“off-track”) will be at increased risk of engagement and instability (i.e. is an “engaging Hill-Sachs defect”).

Thus, there are two factors that contribute to determining if a bipolar bone lesion is on-track or off-track:

Anteroinferior glenoid bone loss

Hill-Sachs interval

Off-track lesions can result from either a large bony Bankart lesion or Hill-Sachs defect, or from a combination of a moderate-sized Hill-Sachs defect and moderate-sized bony Bankart lesion.

Determining on-track or off-track lesions was initially described on CT but can also be calculated on MRI. Two measurements are required 2:

Glenoid track: calculated on a sagittal oblique plane of the glenoid using the best-fit circle method

a best-fit circle is placed on the glenoid, matching the posterior and inferior borders

a horizontal line is drawn through the center of the best-fit circle reaching both anterior and posterior aspects (D)

a second horizontal line is drawn along the same plane from the anterior aspect of the circle to the anterior glenoid (d), i.e. measuring the width of anterior glenoid bone loss

Glenoid track = (0.83 x D) - d

Hill-Sachs interval = Hill-Sachs defect + bone bridge between the rotator cuff attachment and lateral aspect of the Hill-Sachs defect: measured in the axial plane

A bipolar lesion is said to be engaging if the Hill-Sachs interval is larger than the glenoid track.

non-engaging, on-track Hills-Sachs defect = Hill-Sachs interval < glenoid track

engaging, off-track Hills-Sachs defect = Hill-Sachs interval > glenoid track

Question 20

3 Mechanisms for posterior shoulder dislocation?

Answer 20

1. trauma (posterior dislocation)
2. microtrauma (posterior instability) common in lineman, weight lifters, overhead athletes ; insidious onset and presentation
3. seizures and electric shock

Question 21

What are the associated conditions with posterior shoulder instability?

Answer 21

Question 22

Difference in presentation between traumatic and chronic instability?

Answer 22

◦ chronic instability often presents with insidious onset, and vague symptoms (usually pain and not instability as opposed to anterior instability)

often in sporting or occupational activities that require repetitive pushing with the arm in forward flexed position foot ball lineman, weight lifters, etc

shoulder locked in an internally rotated position common in undiagnosed posterior dislocations

pain on flexion, adduction and internal rotation for posterior instability

Question 23

What are the provocative tests - performed in the setting of chronic posterior instability ?

Answer 23

▪ Posterior load & shift test

place patient supine with arm in neutral rotation with 40 to 60° abduction and forward flexion, load humeral head and apply anterior and posterior translating forces noting subluxation

Jerk test

place arm in 90° abduction, internal rotation, elbow bent

apply an axial force along axis of humerus and adduct the arm to a forward-flexed position

a ‘clunk’ is positive for posterior subluxation

97% sensitive for posterior labral tear when combined with a Kim test

Kim test

performed by having the patient seated, arm at 90° abduction, followed by flexing the shoulder to 45 forward flexion while simultaneously applying axial load on the elbow & posterior-inferior force on the upper humerus.

test is positive when pain is present

posterior stress test

stabilize scapula and look for posterior translation with a posterior direct force

pain is elicited often, but this is not a specific finding

Posterior Load & Shift Grading

1+

apparent translation but not to rim

2+

translation to glenolabral rim

3+

translation over glenolabral rim

4+

translation with complete dislocation

Question 24

Best view to demonstrate a posterior dislocation?

Answer 24

axillary lateral

Question 25

View to check for posterior dislocation of the shoulder if patient can’t abduct arm?

Answer 25

Velpeau view if patient is unable to abduct arm for axillary view

Question 26

Indications for CT in posterior dislocations of the shoulder?

Answer 26

Analyze the extent and location of bone loss in a chronic dislocation (>2 to 3 weeks)

Question 27

What is the conservative management for (Posterior shoulder instability)

Answer 27

◦ acute reduction and immobilization in external rotation for 4 to 6 weeks

should be initially attempted for all acute traumatic posterior dislocations

most dislocations reduce spontaneously

technique

immobilize in 10-20 degrees of external rotation with elbow at side

after 6 weeks advance to physical therapy (rotator cuff strengthening and peri-scapular stabilization) and activity modification (avoid activities that place arm in high-risk position)

Physical therapy

may be a first line treatment for chronic posterior instability with rotator cuff strengthening, peri-scapular stabilizers may be considered for the in-season athlete

Question 28

What are the surgical treatment options for posterior shoulder instability?

Answer 28

open or arthroscopic posterior labral repair (Bankart)

recurrent posterior shoulder instability despite appropriate course of physical therapy

continued pain with loading of arm in forward flexed position (bench press, football blocking)

negative Beighton’s score

outcomes

80% to 85% success at 5- to 7-year follow-up after open repair

similar outcomes with arthroscopic repair after shorter follow-ups

open or arthroscopic posterior capsular shift and rotator interval closure

Indications: positive Beighton score

posterior glenoid opening wedge osteotomyindications

excessive congenital glenoid retroversion

limited studies assessing outcomes with this approach

open reduction with subscapularis transfer (McLaughlin) or lesser tuberosity transfer to the defect (Modified McLaughlin)

indications

chronic dislocation < 6 months old

reverse Hill-Sachs defect < 40%

Hemiarthroplasty

indications

chronic dislocation > 6 months old

severe humeral head arthritis

collapse of humeral head during reduction

reverse Hill-Sachs defect > 40% of articular surface

Total shoulder arthroplasty

Indications: significant glenoid arthritis in addition to one of the hemiarthroplasty indications

Question 29

What is the most common complication? What are the other complications? (Posterior shoulder instability)

Answer 29

Stiffness

most common complication after labral repair

Recurrence

2nd most common (7% to 50%)

Degenerative joint disease

3rd most common

Adhesive capsulitis

Overtightening of posterior capsule

may lead to anterior subluxation or coracoid impingement

Nerve injury

axillary or suprascapular