Airport security screening measures have changed substantially during the past decade, but few reports have examined how this affects patients who have undergone knee arthroplasties. The purpose of this study was to characterize the efficacy of airport metal detection of total knee prostheses, the delays faced, any inconvenience this may have caused, and the role of implant identification cards. Ninety-seven total knee arthroplasty recipients reported passing through an airport metal detector, with 70 triggering the alarm a mean of 3 times (range, 1-36). The presence of a single-knee prosthesis triggered airport security alarms more than 83% of the time and increased patient inconvenience. Patients should be informed about this chance and be prepared to present documentation of their prosthesis.