Fractures in general!

Question 1

What is the difference between primary and secondary bone healing?

Answer 1

Primary - occurs when there is minimal fracture gap (less than 1mm) and the new bone simply bridges the gap

Secondary (majority of fractures) - bridging of the gap with a temporary filling which acts as a scaffold for new bone to be laid down. This involves an inflammatory immune response

Question 2

What are the various steps of secondary bone healing?

Answer 2

1. Haematoma formation
2. Soft callus formation
3. Hard callus formation
4. Bone remodelling

Question 3

What cell type forms new soft cartilage?

What cell type lays down new bone matrix?

Answer 3

Chondroblasts form new soft cartilage

Osteoblasts lay down new bone matrix (made up of type I collagen)

Question 4

What process produces immature woven bone (hard callus)?

Answer 4

Calcium mineralisation

Question 5

What is the difference between atrophic and hypertrophic non-union?

Answer 5

Atrophic - failure of initial union (lack of blood supply, nutrients, too large a gap etc.)

Hypertrophic - callus is formed but the bone fragments do not rejoin, caused by excessive movement at the fracture site

Question 6

What are the different fracture patterns?

Answer 6

Transverse

Oblique

Spiral

Comminuted

Segmental

(also Greenstick and Buckle in paediatrics)

Question 7

When describing displacement of a fracture, it is always from the perspective of which segment?

Answer 7

The distal segment

Question 8

When describing angulation of a fracture, it is always from the perspective of which segment?

Answer 8

The direction that the distal segment is pointing in

Question 9

In general, how are the following fracture types managed?

• no displacement, minimal displacement, minimal angulation and that are stable
• displaced or angulated
• unstable injuries

Answer 9

no displacement, minimal displacement, minimal angulation and that are stable - treat with a period of splintage or immobilisation and subsequent rehab

Displaced/Angulated - reduction under GA, ideally closed, and cast application

Unstable - may need surgical stabilisation (K wires, screws, plates, IM nails, external fixation). Unstable extra-articular fractures can be treated with ORIF

Question 10

What is the benefit of using ORIF?

Answer 10

Through using plates and screws with the aim of anatomic reduction and rigid fixation, primary bone healing can occur

Question 11

In what situations should ORIF not be used?

What would be done instead?

Answer 11

Too much soft tissue swelling

Blood supply to the fracture is unreliable

ORIF would pose a risk of substantial blood loss (e.g. femoral shaft)

Plate fixation is prominent (e.g. tibia)

In the above cases, closed reduction and indirect internal fixation with IM nails and dissection distant to the fracture site may be used. The aim with this is functional reduction and stable fixation allowing micromotions, resulting in secondary bone healing

Alternatively, external fixation can be employed (also secondary bone healing but more susceptible to infection)

Question 12

What is Volkmann’s Ischaemic Contracture?

Answer 12

Acute ischaemia in the flexor muscles of the forearm, causing necrosis and resulting in muscle fibrosis and shortening. Especially seen in Flexor Digitorum Profundus (FDP) and Flexor Pollicis Longus (FPL)

Question 13

What are the classic signs of compartment syndrome?

Answer 13

Increased pain on passive stretching of the involved muscle

Severe pain outwith of the severity of the clinical context

Question 14

Define the following terms…

• Neurapraxia
• Axonotmesis
• Neurotmesis

Answer 14

Neurapraxia - temporary conduction deficit in the nerve. Usually resolves within 28 days and complete recovery is seen

Axonotmesis - due to either sustained compression or stretch. Nerve continuity and internal structure is preserved, however the long nerve axons distal to the site of injury die off - Wallerian degeneration

Neurotmesis - complete transection of the nerve