Open fractures are common in veterinary medicine, often affecting bones of the appendicular skeleton. These cases represent a unique combination of soft tissue and orthopedic injuries.
In a recent cross-sectional and case-control study the risk factors for open fractures of the appendicular skeleton in dogs and cats were evaluated.3 The authors found that sexually intact, younger dogs were at a higher risk. Interestingly, toy-breed dogs had a lower risk of open fractures when compared to other breeds in the case group. Bone segments with a higher risk included the scapula, radius or ulna, tibia or fibula and tarsus. Comminuted fractures were strongly associated with an open fracture followed by short oblique fractures. Similarly, sexually intact and younger cats were at a higher risk of open fractures.
Classification systems exist in the human literature and have been used to classify these fractures in veterinary medicine (figures 1 and 2).2 The goal of using such a system is to help provide a prognosis and guide treatment. The use of this system can also help during conversations with a referral surgeon as it provides an understanding of the degree of injury.
As with all trauma cases it is essential to assess the entire patient as, in many cases, comorbidities may prove more life threating than the orthopedic injury. The goals of successful management of an open fracture include preventing infection, promoting fracture healing and restoring function to the affected extremity. Key steps in achieving these goals include prompt and aggressive debridement of contaminated material and nonviable tissue; vigorous irrigation; administration of antimicrobials and restoration of soft tissue coverage to healing bone, tendons, ligaments and neurovascular structures.
The overriding goals of wound treatment in these patients are centered around prevention of further contamination and soft tissue trauma/injury. In many cases sedation and/or general anesthesia is essential, so thorough assessment of the overall patient stability is necessary. The wound should be packed with sterile, water-soluble lubricant. The hair should be clipped widely around the wound to give the surgeon the most flexibility in treating the wound. Gross debris is removed, nonviable soft tissues are debrided judiciously and the wound is lavaged.
The general recommendation for lavage is to use a sterile isotonic fluid at a pressure of 7 to 8 psi which is thought to limit trauma to the viable tissues. Such a pressure can be achieved using a 1-litre fluid bag placed in a pressure sleeve, attached to IV fluid tubing and a 22 to 16-gauge needle with the pressure in the sleeve raised to 300 mm Hg.1,2 In cases of severe contamination, tap water, although not ideal, can be used to remove gross debris prior to lavage. Similarly, the use of a 0.05% chlorhexidine solution has been described. Once the wound is clean a sterile dressing and bandage, often with rigid external fixation (e.g. fiberglass cast splint, aluminum rod) is placed.
The choice of antimicrobial in these cases can be a challenge. One must consider not only the commensal organisms of the patient but also those that have contaminated the wound. It is also prudent to realize that contamination of a wound does not necessarily mean the wound will become colonized and develop an active infection. Similarly, the population of a given wound is not static and can change in relation to many patient and environmental factors. In general, the antimicrobial chosen should be broad spectrum with efficacy against Gram-positive, Gram-negative, aerobic and anaerobic organisms. Some more common isolates include Staphylococcus spp., Streptococcus spp., Klebsiella spp., Pseudomonas spp., Enterobacter spp., and Escherichia coli.
In a prospective study of 1104 open fractures in humans there was a significant decrease in infection rate when antibiotics were administered within 3 hours after injury (4.7%), compared with 4 hours or longer after injury (7.4%).5 The authors also noted that the lowest infection rates occurred when the antimicrobial drugs provided coverage against Gram-positive, Gram-negative, aerobic and anaerobic organisms. Finally, an increased risk of infection was noted when there was a lack of antimicrobial administration; when it was > 4 hours from injury until initiation of antimicrobials; when there was extensive soft tissue trauma; when resistant organisms were present; and when the post debridement-irrigation culture was positive.5
The final consideration regarding the use of antimicrobials in these cases is that surgical site infections are increasingly the result of pathogens acquired in a hospital setting; pathogens that often have some degree of antimicrobial resistance. In attempts to avoid this complication it is best to avoid unnecessarily maintaining an open fracture as this likely increases the rate of nosocomial infection.
Definitive Surgical Treatment
The goals of definitive surgical treatment include preventing infection, promoting bony union, repair of soft tissue damage, and restoring function. Restoration of the soft tissue element is essential for fracture healing and the use of vacuum-assisted closure techniques may be beneficial.2 The Gustilo-Anderson classification scheme can be used to help determine the best surgical treatment. In general, Type I open fractures can usually be treated using the same method of fixation as would be used for a closed fracture of similar configuration. Type II open fractures require the proper management as outlined above and can be treated using the same method of fixation as would be used for closed fractures. Type III open fractures have extensive soft tissue damage which may preclude internal fixation.2 In every case, appropriate, experienced judgment is necessary.
Complications (figures 3 and 4) can occur and counselling owners regarding this potential is important. Widely described complications include: superficial infections, deep-seated infections (may require implant removal), delayed union or nonunion, necrosis of soft tissue with subsequent breakdown of soft tissue repair techniques, and temporary or permanent neurologic damage from the initial injury. In severecases amputation may be necessary and septicemia and death may result from infections treated inappropriately.
These cases can be challenging and at times daunting, but with appropriate and timely treatment, a successful outcome is achievable. If you are unsure or would like to consult on a case, please give our surgery service a call.
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