A prototype device to measure the lumbosacral-sacroiliac range-of-motion

It is estimated that at any given time, 20% of the population experiences lower back pain and that the annual cost to the US industry of this common physical complaint approaches $25 billion. To address this issue, two of the co-authors of this presentation (JM, MJW) have designed and constructed a "pelvic roll" table intended to measure quantitatively the range of motion of the lumbosacral-sacroiliac structures, and to assess the efficacy of osteopathic manipulation. The prototype device has the shape and dimension of a conventional examining table that is divided in the middle at the level of the pelvis. Two lever arm mechanisms on each side of this table are installed between the two halves of the table by which an adjustable force is applied to one or the other Posterior-Superior-Iliac-Spines (PSIS) of a supine subject. A wooden platform spans, and is securely strapped to, the Anterior-Superior-Iliac-Spines (ASIS) of the subject; a conventional low-power laser pointer that is bolted to this platform is pointed along the vector between the two ASIS's to a linear-grid deflection chart.