Figure 2From: Lateral Trunk Motion and Knee Pain in Osteoarthritis of the Knee: a cross-sectional study Trunk motion. Measurement of lateral trunk motion, expressed as the total angle 2α in degrees (i.e. the sum of the movement to the right and left) in the frontal plane (x, z). C7 represents the spinal processus of cervical 7 and S1 represents the spinal processus of sacral 1.Back to article page