3D-location of the L5-S1 fulcrum in relation to the hip.

The purpose of the present study was to measure the three-dimensional distance between the hips and L5-S1 joint in vivo so that this data could then be used in computer programs predicting the load at the lumbosacral joint from posture and anthropometric data. Twenty-one subjects were investigated with computed tomography; consecutive transverse slices were taken from the low-back to proximal thigh, and three-dimensional coordinates were recorded. The distance between the hips and the L5-S1 joint was 122 mm, corresponding to 6.9% and 7.5% of body height for men and women, respectively (P less than 0.05).