Determine the detection rate of modern spinal implants using the current technology.

There is a paucity of data regarding detection rates of modern spinal implants using modern walk-through pulsed archway metal detectors (AMDs). No published reports compare detection capability with hand-held metal detectors (HHMDs).

ex-vivo & in-vivo comparison of detection rates using AMD & HHMD (set to maximum DoT sensitivities), in patients of varying Body Mass Index (BMI), implants, implant mass/density and alloys.

40 patients with: lumbar disc replacement (CoCr) (n=8), cervical disc replacement (CoCr) (1), posterior deformity instrumentation (17), anterior deformity instrumentation (2), anterior reconstruction (2), PLIF (6), interspinous distraction device (1), anterior cervical plate (2) ALIF (1), All implants were titanium unless indicated. Mean metal mass was 98g (range 6g-222g).

The AMD did not detect any instrumentation individually or in combination up to a titanium mass totalling 215g. The HHMD detected all instrumentation at a distance of 5cm; with the minimum mass being 2g

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, BMI, total metal mass, and metal density/segment.

AMD detectors do not detect modern spinal implants. HHMD detect all modern posterior spinal implants; this has implications for patient documentation.