Dislocation of the Shoulder

Question 1

Define dislocation

Answer 1

A dislocation means that the joint surfaces are completely displaced and are no longer in contact.

Question 2

Define subluxation

Answer 2

Subluxation implies a lesser degree of displacement and that the articular surfaces are still partly apposed.

Question 3

What are the clinical features of dislocation

Answer 3

The joint is painful and the patient refuses to move it. The shape of the joint is abnormal and bony landmarks may be displaced.

Question 4

Name and describe a special test for joint dislocation

Answer 4

Apprehension test – If the dislocation is reduced by the time the patient is seen, the joint can be tested by stressing it as if almost to reproduce the suspected dislocation: the patient develops a sense of impending disaster and violently resists further manipulation.

Question 5

Give four reasons the shoulder joint is so commonly dislocated

Answer 5

The extraordinary range of movement; underlying conditions such as ligamentous laxity or glenoid dysplasia and the vulnerability of the joint.

Question 6

What are the three stabilisers of joints?

Answer 6

When assessing joint stability it is essential to know the different stabilisers – bony anatomy, cartilaginous structures and tendons + ligaments which hold the joint in place.

Question 7

Give three specific stabilisers of the shoulder joint

Answer 7

• The glenoid labrum, a fibrocartalignous ring which deepens the glenoid cavity
• The joint capsule around the shoulder
• The coracoacromial ligament, glenohumeral ligaments and coracohumeral ligaments.

Question 8

What is the most common direction of shoulder dislocation?

Answer 8

Shoulder dislocation is anterior in 95-98% of cases, although posterior dislocation can sometimes occur.

Question 9

What is the force generally applied to anteriorly dislocated the shoulder joint

Answer 9

a combination of abduction, extension and a posteriorly directed force on the arm. A fall on an outstretched hand is a common mechanism in the elderly.

Question 10

Describe a shoulder dislocatiom

Answer 10

A fall on an outstretched hand causes the humeral head to be forced anteriorly, out of the glenohumeral joint, tearing the shoulder capsule and detaching the labrum from the glenoid. A fracture of the humeral head, neck or greater tuberosity can occur at the same time.

Question 11

Give the clinical features of anterior shoulder dislocation

Answer 11

Pain is severe and the patient supports the arm with the opposite hand and is loathe to permit examination. The lateral outline of the shoulder may be flattened and if that patient is not too muscular, a bulge may be felt just below the clavicle.

Question 12

What must you always observe in anterior shoulder dislocation?

Answer 12

You must always examine for nerve and vessel injury before reduction is attempted. Check the radial pulse, sensation in the regimental badge area and radial nerve function (thumb, wrist and elbow weakness on extension). The rotator cuff is frequently damaged and should be examined after reduction.

Question 13

What will you see on x-ray of a dislocated shoulder?

Answer 13

The AP x-ray will should the overlapping shadows of the humeral head and glenoid fossa with the head usually lying below and medial to the socket.
A lateral view is required to work out whether the dislocation is anterior or posterior.

Question 14

What first aid procedures should be followed if you discover someone with an shoulder dislocation

Answer 14

The shoulder and arm should be splinted in the abducted position in which they are found. A pillow or rolled blanket can be placed in the space between the arm and chest wall for comfort and support. The elbow should be flexed to 90* and a sling applied to support the arm. The pillow and sling can be secured as a unit to the chest.

Question 15

Outline a method of reducing a shoulder

Answer 15

Stimson’s technique – The patient is left prone with the arm hanging over the side of the bed. After 15 or 20 minutes the shoulder may reduce.
Hippocratic method – Gently increasing traction is applied to the arm with the shoulder in slight abduction while an assistant applied firm counter traction to the body.
Kocher’s method – The elbow is bent to 90 degrees and held close to the body; no traction should be applied. The arm is slowly rotated to 75* laterally, then the point of the elbow is lifted forwards and finally the arm is rotated medially. This technique carries many risks so should probably not be tried.

Question 16

What must be done after succesful reduction of the shoulder joint ?
(3)

Answer 16

After reduction an x-ray is taken to exclude a fracture and a neurovascular examination is performed. The arm is then rested in a sling for three weeks in those 30. Analgesia should be given

Question 17

What is the most common complication of shoulder dislocation in old people?

Answer 17

Rotator cuff – This commonly accompanies anterior dislocation, particularly in older people. The patient may have difficulty abducting the arm after reduction – palpable contraction of the deltoid excludes an axillary nerve palsy. Most do not require surgical intervention.

Question 18

What nerve is commonly impinged in shoulder dislocation

Answer 18

Nerve injury – Axillary nerve is the most commonly injured, although occasionally median, radial and musculocutaneous can be impinged.

Question 19

Give two late complications of shoulder dislocations

Answer 19

Shoulder stiffness – prolonged immobilization can cause stiffness, which is an issue in people over 40. Activity should loosen it up.
Recurrent dislocation – If an anterior dislocation tears the shoulder capsule and detaches the glenoid labrum then shoulder can dislocate repeatedly. This is known as Bankart’s lesion.

Question 20

What happens in posterior dislocation?

Answer 20

Much less obvious on examination and can easily be missed. Patient’s sometime present with a long-standing posterior dislocation. The patient usually presents with the arm adducted and internally rotated. Attempted abduction and external rotation are painful – examination resembles a frozen shoulder.