History of Isola-VSP fatigue testing results with correlation to clinical implant failures

William L. Carson, Marc A. Asher, Oheneba Boachie-Adjei, Behrooz Akbarnia, Robert Dzioba, Nathan H Lebwohl

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

The objective was to compare the history of Isola-VSP in vitro fatigue testing results with clinical implant failures from a five-center retrospective survey of 2499 cases to determine if the appropriate types of tests had been performed. To determine the effect of bending iron marks, bends, and connectors on 1/4″ rod fatigue, 4-point bend fatigue tests were conducted. To characterize bone anchor-connector-rod assemblies, unilateral construct flexion fatigue tests were conducted. Clinically 111 components failed: 41 screws, 57 rods, nine transverse connectors, two interbody graft/cages, one extended slotted connector, and one at unreported location. The screw, rod, and connector clinical data correlate to the lower to higher relative fatigue strength respectively of original integral nut screws; rods at bending iron marks, connectors and lordotic bends; original slotted connector, current slotted connector, and straight rods with unblemished surface. In vitro and clinical failure locations also correlated. The transverse connector cross member failed near the longitudinal rod in 8/9 instances. This implies a lateral bending profile similar to that produced by the H construct used to test them in reversed lateral bending. Recommendations relative to ASTM standards/guides include: incorporation of an H construct to test transverse connectors in lateral bending, replacement of fixed-fixed end with fixed-free end assembly in F 1798-97, and replacement of constrained fixtures in F 1717-01 with unconstrained.

Original languageEnglish (US)
Title of host publicationASTM Special Technical Publication
PublisherAmerican Society for Testing and Materials
Pages3-16
Number of pages14
Edition1431
StatePublished - 2002
EventSpinal Implants: Are We Evaluating Them Appropriately - Dallas,TX, United States
Duration: Nov 6 2001Nov 7 2001

Other

OtherSpinal Implants: Are We Evaluating Them Appropriately
CountryUnited States
CityDallas,TX
Period11/6/0111/7/01

Fingerprint

Connectors (structural)
Fatigue testing
Fatigue of materials
Iron
Nuts (fasteners)
Anchors
Grafts
Bone

Keywords

  • Bending iron marks
  • Bent/straight rod
  • Connector
  • Implant failure
  • In vitro test history
  • Pedicle screw
  • Relative fatigue strength
  • Retrospective clinical survey
  • Rod

ASJC Scopus subject areas

  • Engineering(all)

Cite this

Carson, W. L., Asher, M. A., Boachie-Adjei, O., Akbarnia, B., Dzioba, R., & Lebwohl, N. H. (2002). History of Isola-VSP fatigue testing results with correlation to clinical implant failures. In ASTM Special Technical Publication (1431 ed., pp. 3-16). American Society for Testing and Materials.

History of Isola-VSP fatigue testing results with correlation to clinical implant failures. / Carson, William L.; Asher, Marc A.; Boachie-Adjei, Oheneba; Akbarnia, Behrooz; Dzioba, Robert; Lebwohl, Nathan H.

ASTM Special Technical Publication. 1431. ed. American Society for Testing and Materials, 2002. p. 3-16.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Carson, WL, Asher, MA, Boachie-Adjei, O, Akbarnia, B, Dzioba, R & Lebwohl, NH 2002, History of Isola-VSP fatigue testing results with correlation to clinical implant failures. in ASTM Special Technical Publication. 1431 edn, American Society for Testing and Materials, pp. 3-16, Spinal Implants: Are We Evaluating Them Appropriately, Dallas,TX, United States, 11/6/01.
Carson WL, Asher MA, Boachie-Adjei O, Akbarnia B, Dzioba R, Lebwohl NH. History of Isola-VSP fatigue testing results with correlation to clinical implant failures. In ASTM Special Technical Publication. 1431 ed. American Society for Testing and Materials. 2002. p. 3-16
Carson, William L. ; Asher, Marc A. ; Boachie-Adjei, Oheneba ; Akbarnia, Behrooz ; Dzioba, Robert ; Lebwohl, Nathan H. / History of Isola-VSP fatigue testing results with correlation to clinical implant failures. ASTM Special Technical Publication. 1431. ed. American Society for Testing and Materials, 2002. pp. 3-16
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