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.

Inclusion Criteria:

- Patients 18 years or older;

- Scheduled for primary osteosynthesis or placement of a prosthetic device in the
treatment of closed limb fractures;

- Ability to give informed consent.

Exclusion Criteria:

- Known hypersensitivity to cephalosporins;

- Antimicrobial use or symptoms of infection in the week before surgery;

- Pregnancy;

- Immunosuppressive treatment;

- Inability to give informed consent.