The hysteresis loop as a model for low back motion analysis.

The human low back is highly susceptible to dysfunction. Many diagnostic and treatment modalities for low back problems are used subjectively in clinical practice. Availability of a quantitative reference of back motion could improve practice efficiency. This article describes hysteresis and the hysteresis loop as an objective measurement model of low back motion. The authors constructed an instrument that quantifies force displacement responses of the lower back in passive subjects. Hysteresis loops generated by this instrument lay a scientific foundation on which to base diagnostic procedures and therapeutic measures.