A Proposed Medical Application of the Shape Memory Effect: A NiTi Harrington Rod for the Treatment of Scoliosis
Scoliosis is a deformity which develops in the growing spine. It consists of either a single or combination of sideways curvatures leaving a buckled configuration which can be disfiguring and painful, and can cause interference with internal organs. Figure la shows an X-ray of an untreated curvature in a teenage child. Harrington instrumentation for the internal correction of scoliosis accompanied by fusion is currently the surgical technique most widely usedl. A Harrington distraction rod with purchasing hooks is shown in figure 2a. During surgery the hooks are attached to transverse processes of vertebrae above and below the curve to be corrected. The spine is distracted (straightened under tension) by an external device and the rod inserted and made to apply the correcting force by moving the hook along the ratchets closer to its end of the rod. Figure lb shows the X-ray of the same patient as in figure la after instrumentation. This distraction with tension an the concave side is used universally often in conjunction with a compression rod on the convex side to prevent excessive stretching of the spinal column.
KeywordsShape Memory Effect Lateral Load Shape Recovery Distraction Force Corrective Force
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- 1.P. R. Harrington, J. Bone and Joint Surg., 44-A 591 (1962).Google Scholar
- 2.A. B. Schultz and C. Hirsch, Clin. Orthop., 100, 63 (1974).Google Scholar
- 3.T. R. Waugh, Acta Orthop. Scandenavica, Supplementum 93 (1966).Google Scholar
- 4.A. Nachemson and G. Elfström, J. Bone and Joint Surg. 53-A 445 (1971).Google Scholar
- 5.L. S. Castleman, The 5th Annual Biomaterials Symposium, April 1973, Clemson, S. C. and Private Communication.Google Scholar
- 6.D. E. Cutright, S. N. Bhaskar, B. Perez, R. M. Johnson, G. S. M. Cowan, J. Oral Surg. 35, No. 4 (1973).Google Scholar
- 7.P. R. Harrington (Private Communication).Google Scholar