Mechanical testing of spinal instrumentation

R. B. Ashman, J. G. Birch, L. B. Bone, J. D. Corin, J. A. Herring, C. E. Johnston, J. F. Ritterbush, J. W. Roach

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Clinically, implant failure is often the result of fatigue from continuous cyclic loading. Because of the inadequacies of long-run cyclic testing, fatigue susceptibility of implants was investigated by means of strain measurements and stress analysis under physiologic loads. The implants were equipped with strain gauges during load-deformation testing, and the tensile stress (the component of stress-producing fatigue failure in metals) was calculated for that site on the implant. For metals most often implanted for spinal surgery, such as stainless steel and chrome-cobalt alloys, a stress exists, known as the endurance limit, below which failure will not occur, even if cycled indefinitely. By calculating the tensile stresses in an implant and relating them to the endurance limit, the implant's susceptibility to fatigue can be determined at the site of stress analysis without formal cyclic load testing.

Original languageEnglish (US)
Pages (from-to)113-125
Number of pages13
JournalClinical orthopaedics and related research
StatePublished - 1988

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine


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