40. Fractures. Aetiology, symptoms. Biological, physical and clinical assessment of the fracture. Methods of therapy. Cerclage. Intramedullary pinning. Bone plate. External fixation of the bone fractures.

What are some common aetiologies of fractures?

Trauma, jumping, falling, pathological conditions (osteoporosis)

What are the two main types of fractures based on skin penetration?

Open (perforated skin) and closed (skin intact)

What is a complete fracture?

Bone fragments are completely separated

What are the two types of complete fractures?

Displaced (fragments moved) and non-displaced (fragments unmoved)

What are examples of complete fractures?

1. Transverse fracture: at a right angle to bone's long axis

2. Oblique fracture: diagonal to bone's long axis

3. Spiral fracture: at least one part of bone has been twisted

4. Comminuted fracture: bone has broken into several pieces

5. Segmental fracture: bone has broken in at least two places

6. Avulsion fracture: bone has been broken off by lig/tendon

Describe a transverse fracture.

Fracture line perpendicular to the bone's long axis.

Describe an oblique fracture.

Fracture line diagonal to the bone's long axis.

Describe a spiral fracture.

Fracture line twisted around the bone's long axis.

Describe a comminuted fracture.

Bone broken into multiple pieces.

Describe a segmental fracture.

Bone broken in at least two places.

Describe an avulsion fracture.

Bone fragment broken off by ligament or tendon.

What is an incomplete fracture?

Bone fragments are still partially joined.

What are examples of incomplete fractures?

1. Greenstick

2. Linear

Describe a greenstick fracture.

Incomplete fracture, crack in bone tissue.

Describe a linear fracture.

Fracture line parallel to the bone's long axis.

What is the Salter-Harris classification system used for?

Fractures involving the growth plate (physis).

Describe the five types of Salter-Harris fractures.

1. Type 1: Through physis (Straight across)

2. Type 2: Through physis and metaphysis (Above)

3. Type 3: Through physis and epiphysis (Lower)

4. Type 4: Through epiphysis, physis, and metaphysis (Through Everything)

5. Type 5: Crush injury to physis. (CRush)

What are some clinical signs of fractures?

Lameness, pain, non-weight bearing, vocalisation, bruising, angulation.

How are fractures diagnosed?

X-ray (minimum two views: ML, CrCa).

What are the two main types of fracture healing?

Primary (contact healing) and secondary (callus formation).

What characterises primary fracture healing?

No callus formation, direct bone formation, requires rigid fixation.

What are the stages of secondary fracture healing?

1. Haematoma and inflammation

2. Fibrous callus

3. Cartilaginous callus

4. Osseous callus

5. Bone remodelling

What is the Fracture Assessment Score (FAS)?

A method to evaluate fracture healing potential. Mostly used for long bones (diaphyseal fractures)

What is each factor of the FAS scored out of?

1 to 10. A higher score means faster healing and lower risk of implant failure.

What types of factors are assessed in the FAS?

1. Biological (affect how fast bone will heal)

2. Mechanical (affect how stable the fracture is & weight loading)

3. Clinical (relating to the patient and their care)

What are examples of biological factors of the FAS?

1. Age: paediatric patients exhibit significantly faster bone healing than adults or geriatric patients

2. Soft tissue injury: compromise blood supply to bone, decreasing healing potential

3. Region of bone affected: bones of distal extremities (radius & tibia) are surrounded by a smaller volume of muscle & soft tissue, thus exhibit an increased rate of delayed fracture union

4. Health: heal faster than one with health issues.

What are examples of mechanical factors of the FAS?

1. Fracture configuration: Comminuted, non-reconstructable fractures have lower assessment score

2. Patient size: larger dogs exert larger forces on fracture, thus have lower assessment score

3. Presence of single limb versus multiple limb injury.

What are examples of clinical factors of the FAS?

1. Post-op patient cooperation: active patients are poor candidates for external fixators.

2. Patient comfort: presence of an external fixator may inhibit normal limb use for some dogs

3. Owner compliance: owners who are unable or unwilling to perform post operative management for casts are better off having their pet’s fracture managed with internal fixation

How does the FAS help guide treatment decisions?

• High: simpler methods (like casts or external fixators) might be enough

• Low: more robust methods (like plates or rods) are needed to ensure healing and prevent complications like implant failure

What are the goals of fracture treatment?

1. Reposition and stabilise fragments

2. Promote healing

3. Restore function

4. Achieve cosmetic appearance.

What are the two main categories of fracture treatment?

1. External stabilisation

2. Internal stabilisation

What are some indications for external fixation?

When fracture can be reduced with minimal displacement. Usually incomplete fractures of young, healthy animals

What are some types of external fixation?

1. Conservative: Casts, splints, bandage

2. Surgical: external skeleton fixation

What is external skeleton fixation?

Stainless steel/titanium pins are placed transcutaneous & attached to external pin-gripping clamps & connecting bar

What are indications for external skeleton fixation?

Open fractures (radius, ulna) or across joints. Contraindicated when fracture is unstable

What are some benefits and disadvantages to external skeleton fixation?

Advantage: infections are uncommon, less expensive, wide usage

Disadvantage: Bulky for animals

What are the types of frames used in external skeleton fixation?

1. Half-pin splintage

2. Full-pin splintage

3. Combination

What are some surgical methods of internal fixation?

1. Cerclage wire

2. Intramedullary (IM) pins

3. Bone plates and screws.

When is cerclage wire indicated?

Spiral or oblique fractures, combined with IM pin or fixator (Not strong enough to be used as the sole means of repair of diaphyseal long bone fractures)

What are the different types of cerclage wiring?

Full cerclage, hemi-cerclage, tension band.

What is full cerclage wire?

Utilises 360° circumferential wire placed around bone at a fracture site.
This use is generally restricted to diaphyseal segments of long bones.

What is hemicirclage wire?

Wire is placed through (not around) main fragments of bone. Other components of fracture are then enclosed in wire to hold them firmly to main fragment

What is tension band wiring?

A specialised form of hemi cerclage. Use 2 K-wires

What is the principle of intramedullary pins?

Internal fixation in which pins are inserted into medullary cavity of bone & left in for 6-8 weeks. IM pin must fulfil 75% of IM cavity.

IM pins function to resist bending forces placed on fracture site, however an IM pin alone cannot resist rotational forces. Therefore, any fracture is rarely suitable for IM pinning alone, unless fracture interdigitates after reduction

What are some types of IM pins?

1. Steinmann pin

2. Kirschner wire

3. Rush pin

4. Kuntscher nail

What are the two techniques for IM pin insertion?

1. Normograde: drill through both sections at once. From unaffected bone to the fracture site to other side. Preferred over retrograde - minimally invasive.

2. Retrograde: drill from fracture site into bone. Then down into other half of the bone. Performed when normograde cannot be performed likely due to risk of damaging joint.

What is the primary function of IM pins?

Resist bending forces.

What are some methods to reduce rotational forces with IM pins?

1. Adding wires

2. External fixator

3. Multiple pins

4. Plate and screw fixation.

What type of material is used for bone plates/screws?

Titanium (biocompatible)

What types of fractures can bone plates and screws be used for?

Versatile & can be used for most types & locations of fractures

What is the function of bone plates?

Plates neutralise forces (bending, rotation, compression, tension) placed on bone. Plates can be used w/ IM pins for extra support.

What are considerations for removal or leaving bone plates in place?

Most plates are left in place, though some may be removed.

If the animal is growing then remove plates once fracture is healed to avoid bone complications. If older patient - just leave it. Removing plate can be deemed unnecessary surgery.

What are examples of bone screws?

1. Cortical screws: Designed for dense bone.

2. Cancellous screws: For spongy bone.

3. Self-tapping and non-self-tapping screws.

4. Locking screws: Lock into the plate for additional stability

What types of holes can be drilled into the bone fragments to prepare for bone screws?

Gliding hole: Matches screw diameter. Screws glide and don’t hold proximal segment. Without a gliding hole, the screw threads will engage in both the proximal and distal segments, preventing compression.

Threaded hole: Smaller diameter (equal to or less than diameter of the core), drawing the distal bone segment towards the proximal segment with the gliding hole, facilitating compression

At what angle to the fracture should holes be drilled?

90 (perpendicular)

What are the main types of bone plates?

1. Classic plates: Screws fix the plate to the bone.

2. Locking plates: Screws lock into the plate itself, maintaining stability, often used in bridging techniques for complex fractures.

3. Dynamic Compression Plates (DCP): Sloped holes allow the screw to compress bone fragments as it's tightened.

What are the main concepts of bone plates?

1. Protection (neutralisation)

2. Compression

3. Bridging

4. Buttress (antiglide)

What are dynamic compression plates (DCPs)?

Plates with sloped holes that compress bone fragments when screws are tightened.