The purpose of this study was to determine how effectively the torsion meter measures vertebral rotation. Nine thoracic vertebrae from three disarticulated spines were individually rotated through an arc of 0-60 degrees and measured with a torsion meter by three investigators. One hundred forty-four errors were made in the 351 measurements, of which greater than 92% were within +/- 5 degrees. We concluded that use of the torsion meter is an effective way to measure vertebral rotation.