A photoelastic force-indicating spreader for the correction of scoliosis.

: The Harrington rod procedure for the surgical correction of scoliosis may be safely applied only if the spreader is instrumented with a force indicator. A method is described here of providing the surgeon with simple and direct means of controlling the force exerted with the spreader, using a photoelastic transducer with a special device for temperature compensation which is built into the spreader.