Antibiotic Prophylaxis in Orthopaedic Traumatology

The proposed study is a prospective, randomized, double-blinded clinical trial intended to further define the appropriate duration of antibiotic (cefazolin) administration for surgical prophylaxis in the internal fixation of closed fractures. Our hypothesis is that there will be no difference in the incidence of infection between single-dose versus 24 hours of antibiotic prophylaxis. The null hypothesis is that multiple-dose antibiotic prophylaxis will have a decreased incidence of infection.

Research Design:

A prospective, randomized, double-blinded clinical trial will be conducted to evaluate the duration of antibiotic prophylaxis. After investigators obtain Institutional Review Board approval, recruited patients will be randomly assigned to one of two groups. Both groups will receive 1 gram (g) of IV cefazolin prior to incision, per standard protocol at our institution. If a tourniquet is used, the cefazolin will be administered at least 10 minutes prior to inflation. A 2-g dose of cefazolin will be administered IV for patients weighing more than 80 kg. A second 1-g dose of cefazolin will be given three hours later if the patient is still in the operating room. Upon completion of the surgical procedure, Group I will receive 1-g doses of cefazolin every eight hours for the next 24 hours. Group II will receive no additional antibiotic. Instead, they will receive normal saline injection every eight hours as a placebo. Group assignments will not be disclosed to the evaluators responsible for clinical examination or to the patients until the end of the study.

Either an orthopaedic surgeon or nurse practitioner will evaluate the patients for the development of a wound infection. Follow-up will occur at 10-14 days, six weeks, 12 weeks, and every six to eight weeks thereafter until bony union occurs. Wound infection will be defined as one or more of the classic signs and symptoms of inflammation (rubor, calor, tumor, dolor) together with purulent drainage at the operative site. Wound infections will be classified either as superficial (infection of the skin or subcutaneous tissue, not communicating with the bone) or deep (infection that reached bone or material implanted for osteosynthesis). Bacteriological cultures will be obtained in the event of infectious complications, but wound infections will be diagnosed clinically.

Several studies have demonstrated that there are numerous patient-related and treatment-related factors that predispose to infectious complications. We will use several of these factors to assign a risk score to each of the enrolled patients. Each factor will be worth one point for a total score ranging from 0 (lowest risk) to 7 (highest risk). The risk factors are: 1) smoking; 2) age >65; 3) diabetes mellitus; 4) obesity (BMI >35); 5) duration of surgery >3 hours; 6) urinary catheterization (0=no catheter, 1=catheter <48 hours, 2=catheter >48 hours).

Statistical evaluation will be conducted by Student's t-test for patient characteristics and chi square analysis for infection rates. The relation between wound infection and the various possible risk factors will be assessed by forward stepwise logistic regression analysis. Significance will be defined at the P < 0.05 level.