Development of clinical methods for measuring geometric alignment of the thoracic and lumbar spines of wheelchair-seated persons.

This study investigated the use of the geometric alignment of two frontal lines (the sternum and abdominal) for predicting alignment of the thoracic and lumbar spines and for measuring wheelchair-seated posture. The sternum line connects the upper sternum point and the lower sternum point. The abdominal line connects the lower sternum point and the center point between the right and left anterior superior iliac spines. I compared the alignment of these two frontal lines in 10 normal subjects by examining the positions of the spinous processes of their thoracic and lumbar spines in 16 sitting postures. Inclination of the sternum line correlated with that of the thoracic spine in both the frontal and sagittal planes; inclination of the abdominal line correlated with that of the lumbar spine in both planes as well. The length of the abdominal line was correlated with lumbar spine length, and the direction of curvature of the lumbar spine was either convex anterior or posterior.