Session 8 - Workbook - Supracondylar Fracture of the Distal Humerus

Question 1

What is the prevalence of supracondylar fractures?

Answer 1

Supracondylar fractures comprise up to 75% of all elbow injuries.

Question 2

What is the most common mechanism for obtaining a supracondylar fracture?

Answer 2

The most common mechanism is falling from a moderate height onto an outstretched hand with the elbow hyperextended e.g. a child falling off ‘monkey bars’ (a climbing frame).

Question 3

What is the epidemiology of supracondylar fractures?

Answer 3

90% of supracondylar fractures are seen in children younger than 10 years of age, with a peak age of 5-7 years.

Question 4

Which sex is more likely to obtain a supracondylar fracture?

Answer 4

They occur more commonly in boys.

Question 5

What is a patient with a supracondylar fracture likely to present with?

Answer 5

The child presents with pain, deformity and loss of function.

Question 6

Other than falling onto a hyperextended elbow, what is a less common mechanism of obtaining a supracondylar fracture?

Answer 6

[A less common mechanism (5%) is falling onto a flexed elbow (which is the mechanism quoted in TeachMeAnatomy).]

Question 7

What is the name for a supracondylar fracture obtained from falling onto a flexed elbow, and who are more likely to obtain these injuries?

Answer 7

[These ‘flexion supracondylar fractures’ more often occur in the elderly and are not discussed further in this unit.]

Question 8

What is the pathology behind supracondylar fractures?

Answer 8

In supracondylar fractures, the fracture line is usually extra-articular (the joint is not involved) and the distal fragment is usually displaced posteriorly.

Question 9

What are the complications regarding supracondylar fractures?

Answer 9

There are three main complications:
[Malunion
Damage to the ulnar, median or radial nerve
Ischaemic contracture]

Question 10

What causes ‘gunstock deformity’ and what is its medical name?

Answer 10

 Malunion, resulting in cubitus varus.

Question 11

What is cubitus varus also known as, and why?

Answer 11

This is also known as the ‘gunstock deformity’ because it resembles the stock of an old ‘long barrel’ gun

Question 12

What nerves can be damaged in supracondylar fractures?

Answer 12

 Damage to the ulnar nerve (most common), median nerve or radial nerve

Question 13

What artery can cause ischaemic contracture in supracondylar fractures?

Answer 13

 Ischaemic contracture: The brachial artery passes very close to the fracture site and can occasionally be damaged or occluded by a displaced fracture.

Question 14

How does ischaemia of the muscles in the forearm occur in supracondylar fractures?

Answer 14

If reflex spasm of the collateral circulation around the elbow also occurs, there will be ischaemia of the muscles in the anterior compartment of the forearm.

Question 15

What will ischaemia of the muscles in the forearm cause?

Answer 15

This results in oedema and a rise in compartment pressure (compartment syndrome) which further exacerbates the ischaemia as it impedes arterial inflow and, if untreated, the muscle bellies will undergo infarction.

Question 16

What happens as the ischaemic tissue is repaired in ischaemic contracture?

Answer 16

During the repair phase, the dead muscle tissue becomes replaced by scar tissue through fibrosis.

Question 17

What is the name and mechanism of the ischaemic contraction sometimes produced as a complication of supracondylar fractures?

Answer 17

The fibrotic tissue contracts (by myofibroblast activity) eventually resulting in a flexion contracture known as Volkmann’s ischaemic contracture.

Question 18

How does Volkmann’s ischaemic contracture present?

Answer 18

The wrist is typically flexed, the fingers are extended at the metacarpophalangeal joints and flexed at the interphalangeal joints, the forearm is often pronated and the elbow is flexed.

Question 19

How do we minimise risk of complications of supracondylar fractures?

Answer 19

In order to minimize the risk of these complications, it is essential that a prompt and thorough neurovascular examination is conducted in any patient with a supracondylar fracture.

Question 20

What is the treatment if there is compromise to the neurovascular supply of the forearm or hand?

Answer 20

If there is any compromise of the neurovascular supply of the forearm or hand, emergency reduction and fixation of the fracture (under anaesthetic) is required.