Regional delivery of prophylactic antibiotics in total knee arthroplasty via an intraosseous route

INTERVENTION: Immediately following tourniquet inflation Group 1 would then receive a single 1g dose of cefazolin via an intraosseous cannula into the proximal tibia. The cefazolin would be administered in 200ml of saline solution. CONDITION: Infected total knee arthroplasty PRIMARY OUTCOME: Primary outcome is Cephazolin concentration in tissue. Seven samples will be taken from each patient, 4 fat samples and 3 bone samples. Each sample will be approximately the size of a pinhead. Bone samples will be taken from the femur only to ensure no direct contamination from the site of injection (tibia). Due to the small size of the samples it is anticipated that there will be no detrimental effect on the patient whatsoever. Samples will be stored at Middlemore hospital lab at ‐90 degrees Celsius, before being sent to Christchurch for analysis using a technique called high performance liquid chromatography (HPLC), which will determine the concentration of Cefazolin in each sample. SECONDARY OUTCOME: Nil INCLUSION CRITERIA: Total Knee Replacement patients Osteoarthritis Body Mass Index (BMI)<30