Static plain radiographs at the end of uncontrolled bending are the current standard of care for measuring translatory slip in back pain patients. Quantitative fluoroscopy systems (QF) that employ standardised bending protocols have been found to improve precision and reduce dose, but comparative data are lacking. We compared 4 QF methods with static radiographs in a control population, calculating ranges, population variation and measurement errors over 6 weeks. Fifty-four healthy controls (F=22, M=23) received passive recumbent and active weight bearing QF screenings during controlled motion, plus still fluoro imaging in neutral, flexion and extension. The translatory slip of all levels from L2-S1 was determined for each condition using bespoke image tracking codes (Matlab) and pooled to provide means and ranges of variation (+/-1.96SD). The pooled measurement error, or minimal detectable change (MDC95), reflecting the intra subject repeatability over 6 weeks was calculated. Ranges of translation for each level (L2-S1), for each type of motion were also calculated.Purpose and background
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