Fractures

Question 1

Biology of bone healing

Answer 1

The periosteum provides vascular supply that plays an essential role in fracture healing. The periosteum in children is substantially thicker and more robust than in adults accounting for more rapid healing.

Question 2

Stages of bone healing

Answer 2

1. Inflammatory: dominated by vascular events. Following a fracture, hematoma forms which provides the building blocks for healing. Subsequently, reabsorption occurs of the 1-2mm of bone at the fracture edges that have lost their blood supply.
2. Reparative phase: new blood vessels from outside the bone that supplies nutrients to the cartilage, which begins to form across the fracture site. Nearly complete immobilisation is desirable during the both the inflammatory phase and the early reparative phase to allow for the growth of these new vessels. However, once neovascularisation is complete, progressive loading and stress across the fracture site are desirable to augment callus formation. The callus is initially highly cartilaginous but hardens as mineralisation and endochondral calcification occur during the remodelling phase. late in the reparative phase, clinical union of the fracture occurs.
3. Remodelling phase: the endochondral callus becomes completely ossified and the bone undergoes structural remodelling. Common conditions that impair fracture healing include DM, arterovascular disease, anemia, hypothyroidism, malnutrition, excessive chronic alcohol use and smoking. Specific medications may also impair fracture healing, including NSIADs, glucocorticoids and certain antibiotics.

Question 3

Fracture description

Location

Answer 3

Proper fracture description begins with precise identification of the injured bone. Once the fractured bone is identified, the aspect of the injury is described using precise anatomic terms such as medial or lateral. Long bone fractures should be described using the involved regions of the bone: metaphysis, diaphysis, epiphysis. Diaphyseal fractures are further characterised as involving the proximal, middle or distal third of the bone.

Fractures that extend into a joint space are referred to as ‘intra-articular’. Intra-articular fractures are characterised by the percentage of the joint space they disrupt eg: involving 30% of the joint space.

Question 4

Fracture description

Orientation: transverse, oblique and sprial

Answer 4

A fracture line may have one of 3 possible orientations: transverse, oblique or spiral. Transverse fracture lines travel perpendicular to the long axis of the bone. Typically caused by a direct force, transverse fracture is the most common type.
Oblique and spiral fractures run diagonally down the long axis of a bone.

Question 5

Fracture description

Displacement and angulation

Answer 5

Angulated or displaced fractures result in the loss of normal anatomic alignment. These fracture types common result in more severe soft tissue injuries than nondisplaced fractures. By convention, any fracture malalignment is described by referring to movement of the distal fragment relative to the proximal bone.
Displacement can be quantified by the percentage of bone that is maligned eg: 75% medially displaced.
Special cases of displacement occur when fracture ends are crushed together (impacted) or pulled apart (distracted).

Angulation refers to motion relative to the long axis of the bone. When describing angulation, both the direction and the degree of malformation are important.

Question 6

Hand Fracture

Answer 6

Common sites of injury: finger tip (crush fracture), Base of distal phalanx (mallet finger), neck of 5th MC (boxer’s fracture)
Thumb injuries: Skiers thumb - ulnar collateral ligament injury at the MCPJ. May have an associated avulsion injury and require US to confirm diagnosis
Bennett’s fracture - # to base of 1st MC. Unstable as technically intra-articular and fracture/dislocation
Comminuted intra-articular fracture through the base of 1st MC is called Rolando fracture

Question 7

Wrist Fracture

Answer 7

Aged related injuries:
4-10 = Torus and greenstick fractures
11-16 = Salter-harris injuries
17-40 = Scaphoid and triquetral fractures
40-60 = Colles/Smiths fractures

Alignment: Gilula’s arch should be parallel and 1-2mm apart
Radial inclination: 20-25 degrees
Radial length: 10-13mm
Volar tilt: 12degrees

Question 8

Elbow fracture

Answer 8

Radio-capitellar line should dissect the capitellum
Anterior humeral line (along the anterior humeral cortex) should have a third or more of the capitellum anterior to it.

Haemarthrosis in the elbow will cause displacement of anterior fat pad causing appearance of the sail sign, indicative of a fracture at the elbow.
The posterior fat pad may be displaced by a very large effusion and shows up as a thin black line posterior to the cortex of the distal humerus

Question 9

Shoulder Fracture

Answer 9

Rockwood AC joint injury classification:
Type 1 - no joint separation
Type 2 - AC joint disrupted with a slight vertical separation
Type 3 - CC distance of 25-100% of other side
Type 4 - lateral end of the clavicle is displaced posteriorly through trapezius as seen on the axillary x-ray
Type 5 - CC distance > 100% of other side
Type 6 - inferiorly displaced clavicle

Neer’s classification of proximal humeral fractures
1 part - no significant displacement across fracture lines
2 part - displacement across one fracture
3 part - some displacement across 2 fractures
4 part - serious displacement across 3 fractures, severe comminution