Type of Study:
This is a multicenter, single arm, retrospective/prospective clinical trial.
Treatment Group:
• The treatment group includes any patient with an acute perioperative infection, an acute hematogenous, or a chronic infection with unresectable components and treated with intraoperative intraosseous vancomycin during a one-stage debridement protocol. Additionally, patients will be treated with at least 4 weeks of IV antibiotics under guidance of an infectious disease specialist, and indefinite antibiotic chronic suppression.
Surgical and Antibiotic Administration Technique:
Initially, all patients will receive standard weight based cefazolin (1 gram for patients \< 80kg, 2 grams for patients between 80-120kg, and 3 grams for patients over 120kg) preoperatively. Our protocol for MRSA positive patients is to use cefazolin and vancomycin preoperatively. Because irrigation and debridement in patients with gram positive infections are frequently done urgently before exact organism identification and sensitivities are available it is important to cover the patient broadly with cefazolin and vancomycin initially.
The treatment group will receive post debridement intraosseous vancomycin as described below. In total knee infections a pneumatic tourniquet must be used for the procedure. After entering the knee joint the following process is followed:
1. Fluid is collected in four syringes and placed into two sets of aerobic and anaerobic adult blood culture bottles,
2. Two synovial tissue cultures from different areas of the joint are obtained and sent for culture,
3. If not enough fluid is obtained send an additional tissue culture,
4. Remaining tissue is sent for final pathologic analysis at the end of the case.
After obtaining cultures radical synovial debridement is performed debriding the inner surface of the entire knee capsule including the posterior capsule of the knee. Modular parts will be removed, that is the polyethylene insert for knees.
Debridement and Irrigation Protocol:
After a complete synovectomy is performed along with extraction of modular parts any exposed metallic parts will be scrubbed with a sterile brush soaked in dilute betadine. A 5-step irrigation protocol will then be used for all surgeries:
1. Pulse lavage with 3 liters of normal saline (NS),
2. Lavage with 100 cc's of 3% H202 and 100 cc's of sterile water, a 50/50 solution left in wound for 2 minutes,
3. Lavage 3 liters NS,
4. Lavage with 1 liter of dilute, sterile Betadine (22.5 ml Betadine/liter NS) - left in wound for 3 minutes
5. Pulse lavage with 3 liters of NS
After debridement and irrigation the interventional group will receive intraosseous vancomycin 500mg in 150ml of normal saline. This dose was selected based on the studies of Young (10) and Clarke (11) who used this dose in two high risk groups (revision TKA and high BMI patients) with no significant side effects or red man syndromes. This solution will be prepared by the hospital pharmacy and administered via an EZ-IO intraosseous cannula. In total knees the cannula will be placed in the proximal medial tibia using a starter drill slightly smaller than the diameter of the cannula to ensure a press fit just distal to the tibia implant in the vicinity of the pes anserine tendons. 75ccs of the vancomycin solution will be injected as a bolus. Subsequent to this the remaining 75ccs will be placed in the distal femur just proximal to the femoral component evenly split between the medial and lateral femoral condyles.
After irrigation and debridement the wound will be closed over a betadine soaked lap sponge placed between the components. Contaminated drapes and instruments will be removed and the patient will be re-prepped with new drapes. New instruments will be used to insert the new modular parts. After opening the wound and prior to inserting new modular parts the wound will be irrigated this time with the following regime:
1. Pulse lavage with 3 liters of normal saline (NS),
2. Lavage with 100 cc's of 3% H202 and 100 cc's of sterile water, a 50/50 solution left in wound for 2 minutes,
3. Lavage 1 liters NS,
4. Lavage with 1 liter of dilute, sterile Betadine (22.5 ml Betadine/liter NS) - left in wound for 3 minutes
5. Pulse lavage with 3 liters of NS
After the modular parts are reinserted the wound is closed with monofilament sutures over drains.
Post-operative treatment will be managed by an infectious disease specialist with at least four weeks of intravenous antibiotics followed by indefinite chronic suppression as recommended by the Musculoskeletal Infection Society (Table 1). Baseline creatinine will be obtained preoperatively and on postop days 1 and 2. Infectious disease consultants will monitor peak and trough levels based on the specific antibiotic administered and they will adjust dosage as indicated.
