Overview
Antibiotic prophylaxis in orthopaedic surgery is used to prevent surgical site infections (SSI) by administering antimicrobial agents before microbial contamination can occur during surgery. Orthopaedic procedures frequently involve implants such as plates, screws, prostheses, or nails, which significantly increase the risk of infection because bacteria can adhere to implant surfaces and form biofilms.
The goal of prophylactic antibiotic therapy is to maintain adequate antimicrobial concentration in the tissues at the time of surgical incision and throughout the duration of the procedure. Appropriate timing, drug selection, and dosing are critical factors that determine the effectiveness of prophylaxis.
Rationale for Antibiotic Prophylaxis
Orthopaedic procedures frequently involve extensive soft tissue dissection and insertion of implants. These implants act as foreign bodies and reduce the number of bacteria required to establish infection.
Even a small number of organisms can colonize implant surfaces and form biofilms, which are difficult to eradicate once established. Therefore prophylactic antibiotics play a crucial role in preventing postoperative infections.
- Reduces risk of surgical site infection
- Prevents implant colonization
- Decreases postoperative morbidity
- Reduces need for revision surgery
Common Causative Organisms
Most orthopaedic surgical infections are caused by skin flora introduced during surgery.
| Organism | Characteristics |
|---|---|
| Staphylococcus aureus | Most common pathogen |
| Staphylococcus epidermidis | Common in implant infections |
| Streptococcus species | Less common but significant |
| Gram negative bacilli | Seen in trauma and open fractures |
Commonly Used Antibiotics
The choice of antibiotic depends on the type of surgery, patient risk factors, and local bacterial resistance patterns.
| Antibiotic | Indication |
|---|---|
| Cefazolin | Most common prophylactic antibiotic |
| Cefuroxime | Alternative cephalosporin |
| Vancomycin | MRSA risk or beta-lactam allergy |
| Clindamycin | Alternative in penicillin allergy |
Timing of Antibiotic Administration
The timing of prophylactic antibiotics is critical to ensure adequate tissue concentrations during surgery.
- Administer within 60 minutes before incision
- Vancomycin may be given within 120 minutes before incision
- Repeat dosing for prolonged surgeries
- Discontinue within 24 hours postoperatively in most cases
Antibiotic Prophylaxis in Open Fractures
Open fractures have a high risk of contamination and infection. Early administration of antibiotics significantly reduces infection rates.
| Gustilo Grade | Recommended Antibiotic |
|---|---|
| Type I and II | First generation cephalosporin |
| Type III | Cephalosporin + aminoglycoside |
| Farm injuries | Add penicillin for anaerobes |
Complications of Antibiotic Use
- Allergic reactions
- Antibiotic resistance
- Clostridium difficile infection
- Drug toxicity
Key Exam Points
- Cefazolin is the most commonly used prophylactic antibiotic in orthopaedic surgery
- Administer within 60 minutes before incision
- Repeat dose if surgery lasts longer than 3–4 hours
- Open fractures require early antibiotic therapy
- Antibiotics are usually discontinued within 24 hours