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 < 0.05).