Classification of Open Fracture. Open fractures are graded by the severity of soft tissue damage, fracture pattern, and degree of contamination, as defined by Gustilo and Anderson (see Plate 9-3). In type I open fractures, the wound is less than 1 cm in length and is free of contamination. Type II fractures have a wound greater than 1 cm, but less than 10 cm, in length, and the soft tissues are not extensively stripped from the bone. In type IIIA fractures, the wound is larger than 10 cm but soft tissue coverage remains adequate. In type IIIB fractures, the wound is larger than 10 cm, the periosteum is stripped from the bone, and the bone is exposed. Type IIIC fractures have a large wound greater than 10 cm in length and have significant arterial injury that requires surgical repair. All type III injuries are generally considered contaminated and many times are the result of a high-energy gunshot, farm injury, or blast. Gustilo and colleagues noted that the incidence of infection was 1% for type I fractures, 1.8% for type II fractures, and 20.8% for type III fractures.

Contamination of Open Injury. The most important factors contributing to wound infection of an open fracture are the degree of contamination and the severity of the injury. However, even a type I wound may become infected if not adequately cleaned and treated. The potential for infection due to various strains of Clostridium (e.g., tetanus and gas gangrene, see Plate 9-5) always exists, because clostridia are ubiquitous and every contaminated wound may contain them.

Injuries at high risk for infection include wounds contaminated by manure or standing water (which often contains clostridia) and wounds caused by a high-velocity mechanism, such as a gunshot. An open fracture of the toe caused by a lawn mower blade, for example, is a very high-risk wound. The high velocity of the blade edge imparts tremendous energy, increasing soft tissue damage and the risk of contamination. Even in some wounds that appear trivial (e.g., a puncture in the sole of the foot caused by a rusty nail), particularly virulent organisms are inoculated deep into the wound, causing a significant infection. A puncture in the heel that penetrates the calcaneus would be classified as a type I wound; however, this type of puncture wound is notorious for becoming infected, in part because the initial treatment was inadequate. In addition, these puncture wounds are often contaminated by gram-negative organisms, such as Pseudomonas, which can cause a chronic infection that is very difficult to cure.

Puncture wounds resulting from human bites are also serious and are often initially overlooked by the patient. In a fist fight, a metacarpophalangeal joint may be punctured by a tooth and contaminated by anaerobic or microaerophilic bacteria contained in the mouth. These organisms can cause especially aggressive and destructive infections in the hand (see Section 8, Soft Tissue Infections, Plate 8-2). Because of this risk, the gold standard of treatment for all “fight bites” is surgical washout of the involved metacarpophalangeal joints.

Failure to remove contaminating organisms from an open fracture site may result in severe complications. Acute infections with Clostridium species, as well as with streptococci and other bacteria, can lead to cellulitis, sepsis, and even death. Even if acute infections do not develop, osteomyelitis, a low-grade chronic infection of bone, may result (see Section 8, Soft Tissue Infections, Plates 8-2 to 8-9). This condition is distinguished from soft tissue infections by its persistence and severity. Once established, osteomyelitis is very difficult to eradicate. Although soft tissue infections are usually cured by incision and drainage, bacteria can become sequestered in bone, where perfusion is inadequate and bactericidal antibiotic levels cannot be achieved. Chronic osteomyelitis may not respond to surgical debridement and intravenous antibiotics, and purulent drainage often persists.

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Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Infection
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