Although the wounds associated with an open fracture attract your immediate attention, the first priority is to ensure that the patient is properly evaluated and stabilised. During this process, the wound is covered with a sterile or clean dressing to prevent further contamination and to control any haemorrhage.

Open fractures have a soft tissue wound that exposes the bone to the external environment. There is an increased risk of osteomyelitis at the fracture site due to contamination and infection of the soft tissue wound. The extent of the fracture and soft tissue wound is determined by the level of energy causing the injury.

Open fractures vary widely in severity from simple punctures to serious tissue loss. They are classified into three types or grades, based on the extent and duration of the soft tissue wound. This classification helps us to decide on the best type of fracture management, and the likely prognosis.

Classification

 Type I injury: Fractured bone fragments puncture through the skin from within.

 Type II injury: External trauma causing the fracture also inflicts a wound from outside, causing a skin and soft tissue deficit which communicates with the fracture site. Also hair, dirt and asphalt (grit) may be driven into the wound.

 Type III injury: Extensive skin, subcutaneous tissue and muscle injury from the external trauma. Often associated with soft tissue avulsion and degloving injury, gunshot, neurovascular injury or traumatic amputation. All type III fractures develop some degree of infection. Open type I and II fractures that become infected due to delayed treatment are included in this group, because their management is similar.

Infection

The major factors that determine whether infection develops in open fractures are the severity of the bacterial contamination, extent of damage to bone blood supply, soft tissue necrosis, foreign material, insufficient debridement, absence of drainage and delay in treatment. Treatment of an open fracture is to be regarded with some urgency and it should be undertaken as soon as the animal's overall condition allows.

Treatment

Treatment is in two parts: wound debridement and fracture stabilisation.

Wound Management and Debridement

1.  All animals with open fractures are given prophylactic, broad-spectrum antibiotics immediately.

2.  Cover the open wound with a sterile dressing as soon as the animal is admitted, to prevent a nosocomial infection. If a dressing is already covering the wound, leave it in place until you are ready to debride and clean the wound. Sedate or anaesthetise the animal if possible, to facilitate the wound management.

3.  Radiographs are taken of the fracture without removing the dressing, to prevent further contamination.

4.  Clip the hair from a wide area of skin around the wound, and scrub the limb with povidone-iodine solution. In animals with other life-threatening injuries that preclude anaesthesia, the wound is irrigated with sterile saline solution to remove as much contamination as possible. The wound is covered with sterile dressings that are changed daily until surgical debridement can be performed.

5.  Normally surgical debridement is performed as soon as possible, using a standard surgical pack in the operating room.

Type I open fractures require very little debridement, except perhaps sharp excision of necrotic tissue if any, before fracture fixation.

Types II and III require more extensive debridement. Prepare and drape the limb. Sharply excise necrotic skin, fat, fascia and muscle from wound. Swabs of necrotic tissue and from deep within the wound are taken for microbiology and sensitivity testing. Remove all foreign material such as dirt and hair with flushing and careful debridement. Tiny chips of bone can be discarded, but all other bone fragments are kept. Take care to preserve soft tissue attachments and blood supply to bone fragments. If these bone fragments do become sequestra, due to subsequent infection, they are removed at that time. Irrigate and clean, but do not excise tendon, ligament, cartilage, vessels or nerves. Lavage the wound with 1–2 l of warm saline with a 60 ml syringe.

Fracture Fixation

 Stabilisation of the fracture is not done until the wound has been debrided as above.

 A new sterile surgical pack and drapes are used for the open reduction and fracture stabilisation, to prevent the transfer of contamination from the dirty wound.

 Stabilisation of the fracture with an external fixator or internal fixation is preferred over splints, because it makes wound management easier. Also, the patient is less painful with a stable fracture.

Type I and many type II open fractures can be stabilised as if they had been closed initially. More stable techniques of fixation such as plating or an external fixator are generally better than unstable techniques. Generally intramedullary pinning is avoided because it allows some continuing fracture instability. Fractures can heal even with the presence of pathogenic bacteria, provided the fracture is absolutely stable.

The surgical approach for open reduction and internal fixation is performed via a second incision, away from the traumatised tissue and initial wound if possible.

The surgical incision that was made for the fracture fixation is closed primarily with sutures. The traumatic wound is usually not sutured. At the end of the surgery, it is covered with a sterile dressing, which is changed on a daily basis, until the wound heals by second intention. During this period, the wound must be observed carefully to detect suppuration, or development of deeper infection or abscesses.

Type III open fractures and all infected open fractures of the diaphysis are usually stabilised with an external fixator. This method provides good fracture stability. It can be applied without enlarging the initial traumatic wound, and so avoids further loss of soft tissue attachment or damaging bone blood supply. Furthermore, the fixation pins are inserted through healthy tissues, away from the fracture site. In the face of infection, implants become colonised by bacteria which cause persistence of infection. This is not necessarily a problem, although the implants will need to be removed after the fracture has healed.

The external fixator can be used as the definitive fracture stabilisation until the fracture heals, or else it can be replaced by a plate after healing of the soft tissues and resolution of infection has occurred.

Bone Grafting

Autogenous cancellous bone collected from the proximal metaphysis of the humerus or tibia is packed into defects and around the fracture site, especially in adult animals. In all type I and selected type II open fractures, the bone grafting is done at the same time as the fracture stabilisation. Cancellous bone grafts are not at risk of becoming a sequestrum. In type III and obviously infected fractures, cancellous bone grafting is done as a delayed procedure, 7–10 days later. The graft is packed around the fracture site, underneath the granulation tissue which will have formed. Alternatively, it can be inserted next to the fracture, via a separate surgical approach made through healthy tissue.

Postoperative Care

 Keep wounds covered with sterile dressings that are changed on a daily basis.

 Clean wounds by gentle irrigation with sterile saline, and using sterile gloves and instruments. Most wounds will heal by second intention, without the need for reconstructive procedures.

 Prevent the animal from disturbing the bandage or wound by application of an Elizabethan collar.

Antibiotics

Antibiotic therapy is given for at least 10 days. Broad-spectrum oral antibiotics that are effective against beta-lactamase-producing Staphylococcus infection are preferred (for example amoxicillin-clavulanate, 20 mg/kg q8h) unless the culture results indicate another drug is needed. For open fractures that become complicated by osteomyelitis, more prolonged therapy is indicated.

Complications

 Chronic infection may develop, especially if there is foreign material, sequestrum, fracture instability or loose implants present at the fractures site.

 Union may be delayed in open fractures due to infection, devitalisation of bone, poor reduction, fracture instability and bone loss.