The use of patient-specific instruments for total knee arthroplasty shifts computer navigation for bone landmark registration and implant positioning from the intraoperative to the preoperative setting. Each system requires preoperative MRI or CT, with specifications determined by the instrument manufacturer. The marketed advantages of patient-specific instruments include greater accuracy in coronal alignment with fewer outliers, no need for instrumentation of the intramedullary canal, reduced surgical time, lower side effects, and improved clinical outcomes.