Efficacy and Safety of Intraosseous Antibiotic Prophylaxis in Total Hip Replacement: A Prospective Randomized Controlled Trial

The goal of this clinical trial is to learn if intraosseous antibiotic (cefazolin) administration can improve antibiotic levels in adults undergoing primary total hip replacement. The main question it aims to answer is: • Does intraosseous cefazolin increase antibiotic concentrations in blood and tissue compared with standard intravenous cefazolin alone? Researchers will compare patients receiving intraosseous cefazolin plus standard intravenous cefazolin to those receiving placebo injection plus standard intravenous cefazolin to see if local antibiotic delivery improves outcomes. Participants will: * Receive standard intravenous cefazolin before surgery and either intraosseous cefazolin or placebo * Provide blood samples before and after antibiotic administration * Have small tissue samples collected during surgery * Complete routine postoperative follow-up and outcome assessment for 90 days

Inclusion Criteria: * The subject population will include all patients over the age of 18 scheduled to undergo primary total hip replacement receiving antibiotic prophylaxis for prosthetic joint infection with the institution standards i.v. bolus dose of cefazolin just prior to surgery. Exclusion Criteria: * Patients with reduced renal function (GFR \< 30), reduced liver function (AST/ALT \>3x upper limit of normal) and weight greater than 120kg will be excluded since these variables may impact cephalosporin pharmacokinetics and pharmacodynamics and confound our results. We will also exclude patients undergoing bilateral total hip arthroplasty. We will also exclude patients with documented cefazolin anaphylaxis, active documented joint infection, history of diabetes, inflammatory arthropathies, patients unable to understand written and/or spoken English and those undergoing revision total hip replacement.