Orthopaedic surgeons and trauma surgeons in the Netherlands are implanting 65,000 joint replacements and treating nearly 300,000 fractures per year. For many travellers with a metal implant - but also for the physicians who are treating them - it is unclear what the consequences will be when they have to go through airport security checks. These checks follow a fixed procedure in accordance with European rules which involves travellers passing through a number of visible and invisible barriers. The first barrier is usually a metal detector or a millimetre wave scanner; when the implant has been detected, this is followed by a body search. The electromagnetic field of a metal detector penetrates into the body; the metal detector has therefore a higher detection rate for metal implants than a millimetre wave scanner, of which radio waves reach up to or just below the skin. Medical documentation can help reassure the traveller or the security officer, but possible additional checks cannot be avoided.