Measurement of spinal range of motion in healthy individuals using an electromagnetic tracking device

Object. The authors measured the range of motion (ROM) of the spine in healthy individuals by using an electromagnetic tracking device to evaluate the functional performance of the spine. Methods. The authors used the Flock of Birds electromagnetic tracking device with 4 receiver units attached to C-7, T-12, S-1, and the midthigh region. Forward/backward bending, bilateral side bending, and axial rotation of the trunk were performed in 18 healthy individuals. Results. The average ROM was calculated after 3 consecutive measurements. The thoracic spine generated the greatest angle in axial rotation and smallest angle in backward bending. The lumbar spine generated the greatest angle in forward bending and smallest angle in axial rotation. The hip joints generated the greatest angle in forward bending and smallest angle in backward bending. Additionally, 40% of forward-bending motion occurred in the lumbar spine and 40% occurred in the hip joints. Approximately 60% of backward bending occurred in the lumbar spine; 60% of axial rotation occurred in the thoracic spine; and 45% of side bending occurred in the thoracic spine. Conclusions. The Flock of Birds electromagnetic tracking device cannot only measure the ROM of spine but also easily differentiate the 6-degree contributions by different segments.