Joint dislocation (incl. acromio-clavicular, elbow, shoulder, patella)

Question 1

What is the difference between subluxation vs dislocation?

Answer 1

Dislocation is injury to a joint that causes adjoining bones to no longer touch each other.

Subluxation is a minor or incomplete dislocation in which the joint surfaces still touch but are not in normal relation to each other.

Question 2

What is the most common mechanism for elbow dislocation?

Answer 2

This is usually produced by a fall on the hand with the elbow partially flexed.

Question 3

What is the mechanism of injury for acromioclavicular joint subluxation to occur?

Answer 3

Uncommon - usually caused by fall onto the shoulder e.g. in sports

Question 4

What ligaments are torn in ACJ subluxation?

Answer 4

Superior and inferior AC ligaments

BUT coracoclavicular ligament remains intact

Question 5

What ligaments are additionally torn in ACJ dislocation?

Answer 5

Superior and inferior AC ligaments

AND coracoclavicular ligament

Question 6

What is the management and prognosis of ACJ dislocation/subluxation?

Answer 6

Displacement is difficult to position but function is usually good even without full correction. Subluxation will usually persist.

Broad sling +/- strapping over ACJ

Surgical - only if pain persists –> surgical repair or reconstruction of the coracoclavicular ligament e.g. using screw across clavicle or figure of 8 wire. These can then be removed but subluxation may recur.

Question 7

What are the clinical features of ACJ dislocation/subluxation?

Answer 7

• Prominent outer clavicle
• Swelling
• Restricted shoulder movements

May be missed on XR unless patient holds a weight in hand during the image.

Question 8

Which system ic used to classify ACJ dislocations?

Answer 8

Rockwood system - 6 types

Question 9

What is the mangement of patella dislocation?

Answer 9

1. Reduction usually achieved by straightening the knee
2. Cast or firm bandage - allows the capsule to heal
3. Active mobilisation

Medial patellofemoral ligament can also be repaired or constructed.

Question 10

What is the mechanims of injury in shoulder dislocations?

Answer 10

Fall on arm or shoulder

Question 11

What are the types of shoulder dislocation and which is most common?

Answer 11

• Anterior dislocation is the most common (95%)
• Posterior
• Inferior

Question 12

What are the clinical features of shoulder dislocation?

Answer 12

• Anterior dislocation –> flattening of the deltoid muscle –> loss of curved contour of the shoulder which becomes ‘squared off’
• Posterior dislocation –> less obvious, ‘lightbulb sign’ on XR
• Inferior dislocation –> arm lies in a vertical position beside the patients head
• Pain
• Patient supports arm against all movement
• Humeral head may be palpable - below coracoid or in axilla

Question 13

What is luxatio erecta?

Answer 13

Inferior dislocation

Question 14

When is the ‘lightbulb sign’ seen?

Answer 14

Posterior dislocation

Question 15

What is the Y view of the shoulder and why is it useful?

Answer 15

Lateral scapula shoulder aka Y view is part of the standard shoulder series - pertinent projection to assess suspected dislocations, scapula fractures, and degenerative changes. It is also useful in seeing both the coracoid and acromion process in profile.

The “Y” of this view is formed by the scapula’s body, spine, and coracoid process

Question 16

What imaging is used if there is uncertainty about the dislocation?

Answer 16

CT

Question 17

What are the complications of shoulder dislocation?

Answer 17

• Circumflex (axillary) nerve damage - deltoid paralysis, test sensation over the deltoid
• Brachial artery damage
• Axillary artery damage

Question 18

List 3 methods for shoulder dislocation reduction. What is the management after reduction?

Answer 18

1. Patient lying prone with arm hanging off couch allowing it to be repositioned
2. Hippocratic method - patient supine, arm is pulled down whilst their foot applies counter traction in the axilla
3. Kocher’s method - elbow flexed traction applied then arm adducted across chest. Risk of fracture.

Pain relief given for all methods. XR taken afterwards and arm immobilised in sling for 3 weeks, followed by physiotherapy.

Question 19

What is a Hill Sachs lesion?

Answer 19

A defect visible in the humeral head after several dislocations or on the edge of the glenoid on a lateral XR

Question 20

What is a Bankart lesion?

Answer 20

Lesion where cartilaginous glenoid labrum and capsule is avulsed from the anterior margin of the glenoid

Question 21

What is the management of recurrent dislocations?

Answer 21

Open or arthroscopic stabilisation and repair fo the damaged capsule and labrum.

Question 22

What type of shoulder dislocation is this?

Answer 22

Anterior –> squaring of the shoulder

Question 23

What is the mechanism of injury for an elbow dislocation?

Answer 23

Fall on the hand with the elbow partially flexed

Question 24

What are the clinical features of elbow dislocation?

Answer 24

• Swelling
• Elbow held in flexed position
• Ulna displaced backwards on the lower end of the humerus
• Fractures of the radial head or coronoid process

Question 25

What is the coracoid vs coronoid?

Answer 25

Coracoid = part of the scapula Coronoid = part of the ulna

Question 26

What are the complications of elbow dislocation?

Answer 26

* Median nerve palsy * Brachial artery damage - rare

Question 27

What is the management of elbow dislocation?

Answer 27

1. **Reduction** - this is usually easy and may be done without anaesthesia in the flexed position with fingers around the epicondyles and applying pressure 2. **Immobilisation** in a sling or collar and cuff 3. **Mobilise** as comfort allows

Question 28

What is the mechanism of injury in patella dislocation?

Answer 28

Fall or blow to the side of the knee- usually in children and young adults. Patella dislocates laterally and the knee remains flexed until the patella is reduced.

Question 29

What other injury occurs in patella dislocation?

Answer 29

Tear of the medial capsule Quadriceps expansion

Question 30

What sign is seen in patients prone to recurrent patella dislocations?

Answer 30

Apprehension sign - occurs if an attempt is made to dislocate the patella laterally

Question 31

What is the management of Rockwood system ACJ injuries?

Answer 31

**type I and II (+/- III):** conservative: ice, analgesics and shoulder rest in a sling **type III:** the current evidence does not support surgical intervention on type III injuries as a general rule; the selection of which patients with type III injuries for surgical intervention is difficult, but patients who are particularly thin, require a great range of motion or do heavy lifting may benefit from operative repair **types IV-VI (+/- III):** surgical internal fixation is typically achieved with a hook plate, which in most cases needs to be eventually removed. K-wires have also been used, although rare cases of wire migration into vital organs, has dissuaded many surgeons from using them