The purpose of this research was to determine if lumbar curvature could be quantified by using only measurements made on the anterior portion of the body. To do this, 31 subjects were tested in four static seated positions as well as dynamic seated postures using a motion capture system. Anterior measurements were used to quantify the relative positions of the ribcage and pelvis in a measure called “openness angle”. Posterior measurements of the lumbar curvature were quantified in a measure called “lumbar angle”. The relationship between the openness angle and the lumbar angle was evaluated using a linear model and a second-order polynomial model for both the static positions and the dynamic postures.

The relationship between the openness angle and the lumbar angle is fit well by both the linear model and the polynomial model in both the static and dynamic cases. Predictions of static lumbar angles of a population developed from linear and polynomial models from a separate population were found to be statistically indistinguishable from the actual lumbar angles. Subject specific predictions of static lumbar angles were also found to be indistinguishable from actual lumbar angles when the subjects’ dynamic models were used for prediction.

These results show reliable predictions of lumbar curvature are possible in static postures by using openness angle in conjunction with a previously determined first or second order calibration model.