Detection of modern spinal implants by airport metal detectors

Prospective cohort observational study.

To determine the detection rates of modern spinal implants by post-9/11 airport metal detectors.

There are few data on the detection rates of modern spinal implants and few that examine the effects of body mass, construct complexity, or implant density.

Implants were tested ex vivo and in vivo using standard arch way metal detectors (AMDs) and handheld metal detectors (HHMDs) in use at the majority of European airports.A volunteer carried individual spinal implants both individually and in various combinations of increasing mass in clothing pockets into the AMD. The same instrumentation was bench tested using HHMD at a distance of 5 cm. Forty patients with modern spinal implants were tested: lumbar disc replacement (8), cervical disc replacement (1), posterior deformity instrumentation (17), anterior deformity instrumentation (2), anterior reconstruction (2), PLIF (6), interspinous distraction device (1), anterior cervical plate (2), and anterior lumbar interbody fusion with cage (1)-all implants were titanium unless indicated. Mean metal mass was 98 g (range, 6-222 g). Subject ages ranged from 13 to 65 years and the mean body mass index was 25 kg/m (range, 15-32).

Ex vivo, the AMD did not detect any instrumentation individually or in combination up to a titanium mass of 215 g. The HHMD detected all instrumentation at a distance of 5 cm, with the minimum mass being 2 g. No implants were detected in patients by the AMD.The HHMD did not detect any anterior lumbar or thoracic surgical implants. It detected anterior cervical implants. The HHMD detected all posterior surgical implants. There was no significant relationship between detection rate, body mass index, total metal mass, and metal density/segment.

AMDs do not detect modern spinal implants. HHMDs detect all modern posterior spinal implants; this has implications for patient documentation.