Ann. rheum. Dis. (1974), 33,136 Measurement of spinal mobility

In the assessment of deterioration or improvement in spinal stiffness it is important to have a measure of spinal range of movement which is reproducible, little subject to observer error, and takes only a short time to perform. In a study ofpatients with ankylosing spondylitis by one of us (FDH), which has continued since 1946, measurements by existing techniques were at first unsatisfactory and unreliable. After 3 years, however, Dunham (1949) reported the use of his spondylometer and since 1950 this has been in con-stant use in our clinic. We have now records of spondylometry using this instrument over a period of 23 years and have found it reliable, quick, and Accepted for publication June 28, 1973. subject to little observer error whether used by one or several assessors. The spondylometer is an instrument consisting of two angled rods measuring 40-6 cm. long, bent 12 6 cm. from their free ends through an angle of 35°. The two rubber cushions of the protractor are placed over the sacrum so that the upper one is just below the 5th lumbar disc and the knob at the top is placed over the vertebra prominens (Fig. la and b). The rods are of brass, 0-6 cm. in diameter, connected at a hinge joint. A protractor is jointed to the free end of one rod at the mid-point of its base and this rod also carries a pointer moving over the protractor scal