Fracture management

Fracture

Complete/incomplete break of bone continuity

Causes of bone fractures

Traumatic, Avulsed, Pathological, Stress and Compression

Traumatic fracture

Direct - blow/injury results in fracture at site of trauma

Indirect - impact/contact made away from fracture site i.e. twisting injury

Avulsed fracture

Bone damaged by violent contraction of attached muscles

Pathological fracture

Spontaneous bone fracture already weakened due to pathological process i.e. neoplasia

Stress fracture

Fatigued bone fractures due to prolonged, repetitive stress

Compression fracture

Cancellous bone fracture after compression, causing collapse in on itself, typically skull or vertebrae

Clinical signs of broken bones

Swelling, heat, bruising, pain, deformity, crepitus (crunching sound bone rubs), function loss, unnatural mobility

Classification of fractures

Open versus closed, anatomical location, number of fragments

Open versus Closed

• Open - broken bone visible through skin. Potentially due to overlying wound exposing bone, or bone fragments poke through skin. Without skin barrier to protect bone, risk of infection greater

• Closed - broken bone remains covered by skin. Reduces likelihood of infection, injury less obvious, therefore damage overlooked/underestimated

Anatomical location

• Articular - fracture associated with joint, implications for movement & healing. Avulsed fractures can occur when attachment of muscles (tendons) ‘rip’ away bone section, leaving fragment free-floating on radiographs

• Diaphyseal - most common, main shaft of bone (diaphysis) broken, due to trauma/pathological

• Physeal - in epiphyseal (growth) plate in immature animal. Significant implications for growing and categories of injury can help determine risk factors

• Epiphyseal - involves ends of bone - epiphyses

• Condylar - involves condyles of long bone

Number of fragments

• Simple - one fracture line, two bone fragments (bone above and below fracture). Heal quickly, without complications

• Comminuted (image) - multiple fracture lines, more than two fragments

• Wedge - multiple fracture lines, some contact between main fragments create patch/wedge pattern damage

• Segmental - one or multiple complete fragments/sections of bone, each segment having intact shaft of bone (360 cortical bone)

• Irregular - multiple fragments, no complete shaft, other than sections above and below injury. Little fragments like shattered glass

• Multiple - multiple fracture lines, across different bones e.g. across digits or involving more than one rib

Salter-Harris (growth plate) fractures

Epiphyseal plate fractures interrupt normal growth processes involved with growth plate, can impact development of limb architecture and have lifelong impact on animals mobility

Fracture grades

• Type 1: Fracture across growth plate, without bone. Best prognosis for repair and normal function

• Type 2: Fracture beyond growth plate, include bone within metaphysis (area above growth plate). Most common Salter-Harris fracture

• Type 3: Fracture beyond growth plate, into epiphysis (end of long bone). Reflects complications associated with joint involvement

• Type 4: Involves metaphysis, growth plate and epiphysis, significant effect on joint development and mobility

• Type 5: Crush injury to growth plate, may unnoticed until animal develops, result angular abnormalities in affected limb

Types of displacement

Greenstick, fissure, depressed, compressed, oblique, spiral and longitudinal

Greenstick

Incomplete fracture of bone in immature animal (not involve growth plate)

Fissure

Fine crack may displace during surgery/stress

Depressed

Flat bones pushed into underlying cavity e.g. skull fractures

Compressed

Compressive force crushes bones into each other, shortening effect on bone(s) e.g. vertebral fracture

Oblique

Fracture line angle of at least 30

Spiral

Fracture line curves around bone, typically twisting injury

Longitudinal

Fracture on longitudinal axis of bone

Dislocation

Clinical signs - deformity, function loss, pain, limb shortening

Does not involve break in bone continuity, but displacement of joint

Sub-luxation

Left hip not snug within acetabulum, some connection between the two.

Articular surfaces reduced contact

Luxation

Left hip sits above acetabulum, no connection between two

Articular surfaces no longer in contact

Congenital dislocation

Anatomical abnormalities at birth, may be inherited

Most common congenital luxation involves patella (dislocated kneecap) small breed e.g. jack russell

Acquired

Trauma e.g. RTA

Ligaments keeping joint in normal position are damaged and joint is forced out of alignment, typically involving hip and elbow

Dislocation correction

Before correction animal movement restricted to reduce trauma to soft tissues surrounding joint

Closed reduction

Manipulation of joint, maintaining structural integrity of skin, thereby reducing infection risk

Technique can be used for full/partial luxations

• Bones either side of dislocation manipulated into position while under anaesthetic

• Strict rest, evaluated frequently to check joint in correct position

• Specialised flexion bandaging technique sometimes used to help keep joint in place: Ehmer sling (image) for hind limb, Velpeau sling forelimb

Surgical correction

Surgical intervention to ensure prolonged stabilization of joint

Increased support of joint - tightening joint capsule/providing prosthetic joints, e.g. total hip replacement

Surgery can re-contour joint anatomy to reduce risk of redislocation.

Post-reduction care

Vital to avoid complications exercise restricted 3-4weeks

Applying bandaging/immobilisation to fractures

Manipulation of site increase risk of traumaising soft tissues, e.g. ligaments, nerves and blood vessels, movement painfuk

Better to restrict movement, allow to assume comfortable postion, await veterinary assessment

Diagnosis

Radiographs, CT/MRI warranted with spinal or skull fractures

Anaesthesia recommended due to manipulation and associated pain

Two views ensure abnormailites identified and degree of displacement determined

Non-affected limb for comparison

Primary fracture healing

When bone ends closely aligned, simple fracture/surgically repaired, direct healing can occur.

Bone cells (osteoblasts) within Haversian canals able to bridge gap between bone fragments, negating stablising fibrous framework (callus)

Secondary Fracture healing

Unstable fracutres/multiple fragments

Increased trauma to soft tissues and medullary cavity results in formation of haematoma - subsequent infiltration of fibrous material to create callus. Haversian remodelling restores normal architecture of bone, unless increased movement of bone fragments occurs during healing, prolonged callus (thickening) or malunion can occur

Rate of healing

Clinical (weight bearing) union averaging 12-16 weeks. Remodelling can continue for months after clinical union.

Assessed by CE and radiographs to determine development, remodelling of callus

Rate of healing points

• Immature heal quicker, geriatric/debilitated longer

• Fractures within cancellous bone often heal quick than cortical bone, as good blood supply promote healing

• Osteomyelitis (bone inflammation) delay healing, reversal with appropriate antibiotic therapy

• Oblique fracture quick heal than transverse, larger contact area promoting tissue re-growth

• Poor reduction (space between fragments/movement connecting edges) slow healing

Non-union

Complete failure of fracture ends to unite

Delayed union

Slowed fracture healing, clinical union not achieved within expected time

Mal-union

Fracture heals in abnormal position

Shortened limb

Inadequate reduction of overriding fracture fragments causing shortening of limb, function severley compromised

Sequestrum

Necrotic bone piece incorporated successfully into fracture repair

Osteomyelitis

Inflammation of bone, bacterial osteomyelitis due to inadequate asepsis during surgery, damaged to local blood supply

Implant failure

Stress applied to surgical implant due to inappropriate selection of implant, due overactive patient, suddent deteroration, instability and pain

Reduction fracture repair

• Reduction - fragments brought together in correct anatomical alignment either:

• Closed - traction applied to bone fragments through skin, manipulated into place

• Open - skin and overlying tissues surgically retracted to visualise fracture, then manipulated into place

Fixation fracture repair

Bone fragments immobilised in correct alignment until clinical union occurs, either directly over fracture or distally (intact bone above and below site). Fragments may also be compressed together to narrow fracture gap, promoting primary healing and speedier recoveries

Principles of fracture fixation

Ensure correct alignment of interrupted bone architecture, restoration of normal function

Immobilising fracture sites

• Restore functional anatomy

• Restore continuity of bone

• Restore bone length

• Restore functional shape

• Maintain soft tissue function

• Prevent pain by fragment movement

• Prevent displacement of bone fragments

• Prevent movement within fracture site, may delay healing or cause non-union

Methods of fracture fixation

External coaption (splints/casts)

Internal fixation (pins, plates, screws and wire)

External-internal fixation (external skeletal fixators)

External fixation/Coaption

Non-invasive, simple, cheap

For minimally displaced fractures, well tolerated

Careful application of splint/cast due to pressure/rubbing sores

Gross limb immobility - muscle atrophy (wastage)

Casts

Moulded to individual contours of limb

Stable fracture site for method to success, at least 50% fracture in contact with adjoining bone. use limited to lower limb (below elbow/stifle) to ensure adequate immobilisation while preventing slippage

Plaster of Paris (POP) can be time-consuming and messy. Resultant cast heavy for smaller patients, increasing slipping, non-use (muscle atrophy) and fragment displacement

Synthetic casts - quickly mould/harden. Lightweight though may not provide sufficient support for heavier patients

Splints

Bandaging techniques e.g. Robert Jones used for simple fractures

Expensive, time consuming, potential for slipping

Splints on own support or into bandages e.g. wooden splints, Zimmer splints, gutter splints

Resin/plastic splints, inflatable splints

Limited to limbs, straightforward fractures, minimal involvement of other structures e.g. muscles/nerves/blood vessels

Internal fixation

Surgical exposure of fracture site

Invasive, expensive, complex, risks of surgery, anaesthetic, infection, implant reaction, soft tissue injury

Accurate reduction and provides rigid fixation.

Repair encourages return to full function, optimal fracture healing, reduced long-term complications e.g. prolonged callus formation

(Implant, intermedullary pins, cerclage wire and plates/screws)

Implants

Join bone fragments together, restoring normal bone architecture. Provide support while bone heal

Remain in situ for life or removed once site healed

e.g. Tension-band wires and Association for osteosynthesis (AO)/Association for study of internal fixation (ASIF) techniques

Intermedullary pins

Placement of metal rod through medullary cavity to join two ends of bone

Cheap, quick, minimal surgical exposure. Pin easy remove once bone healed to avoid implant reactions

Not ideal for all fractures, less stability than other forms, slower heal

Arthrodesis or Kirschner wire used as intermedullary pin in small animals/bones, used in addition to larger intermedullary pin to increase stabilisation or incorporate additional fragments

image - central intermedullary pin, Kirschner wires each side extending into condyles

Cerclage wire

Stabilise fracutres and compress bone fragments, ensuring close connection, optimal healing

Can be used instead of intermedullary pins/Kirschner wire and bone plates. Wire placed around bone fragments, tightened, compressing fragments and increasing support of fracture site

Helpful with multiple fracture fragments i.e. communited fractures

Cerclage wire useful on small non-weight bearing bones e.g. jaw

Plates and Screws

Metal plates held in position with screws, common method of stabilising fracture sites, some capable being bent to closely fit contours of bone

Useful for fragmented bones, multiple screws holding small bone fragments in place while healing

Plates durable and strong, in situ for animal life, providing support for large animals. Can provide accurate reconstruction of bone architecture, enable longevity of support for slow healing fractures

Venebles, sherman and dynamic compression plates most used

External Fixators

Pins driven into bone, proximally and distally to fracture, to stabilise fracture site during healing.

Pins connected on outside of body to one/more connecting bars, allowing compression of site to encourage close contact of fragments and optimal healing

Useful for open/infected fractures, reduced surgical involvement when compared to plate/screw methods, delayed/non-union fractures following intermedullary pin placement.

Useful for highly contoured bones e.g. mandibular fractures

Kirschner-Ehmer system

One/more straight pins to stabilise/compress fracture site

Llizarov system

Circular frame to stabilise/compress fracture site

External fixation concerns

• Prolonged exposure of bone to external environment (internal-external pins). Bone infection serious complication if not managed aseptically

• Loose pins, increased movement if clamps not tight. Increase instability within fracture site, delay healing

• Soft tissue irritation, swelling quickly impinging on metalwork surrounding site. Pain, risk of infection and exudates

Managing external fixation

Rubber tips/silicon coating/bandaging