This is a prospective multicenter study. All patients presenting for revision hip or knee arthroplasty for all indications under the respective surgeon's care may be eligible. Per standard of care preoperatively, all patients must have blood drawn for erythrocyte sedimentation rate(ESR), C-reactive protein(CRP) and D-dimer. Aspiration of the joint in question may be performed at the discretion of the treating surgeon and results documented. Intraoperative samples will also be collected and sent for NGS analysis