Biomechanical testing of a novel four-rod technique for lumbo-pelvic reconstruction

Brian P. Kelly, Francis H. Shen, John S. Schwab, Vincent Arlet, Denis Diangelo

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Study design.: A biomechanical testing protocol was used to study different lumbo-pelvic fixation techniques in a human cadaveric lumbar spine model. Objective.: To compare the in vitro biomechanics of a novel four-rod lumbo-pelvic reconstruction technique with and with out cross-links, to that of a conventional cross-linked two-rod technique. Summary of background data.: Numerous lumbo-pelvic reconstruction methods based on the Galveston two-rod technique have been proposed for cases involving total sacrectomy. Recently a technique that proposes novel use of 4 supporting longitudinal rods across the lumbo-pelvic junction has been reported. No comparative in vitro biomechanical testing has been previously done to evaluate these different reconstruction methods. Methods.: Five spines were evaluated in flexion, extension, left-right lateral bending and left-right axial rotation in a human total sacrectomy model. The model was comprised of cadaveric lumbar spines (L1-L5) with custom fabricated polyethylene blocks used to simulate pelvic fixation. Three conditions were evaluated: Linked Four-Rod, Linked Two-Rod, and Four-Rod (no cross-links). Flexibility and motion data were compared using a one-way repeated measures analysis of variance and SNK tests. Results.: The Linked Four-Rod and Four-Rod conditions significantly decreased flexibility and reduced L5-Pelvic motion over the Linked Two-Rod construct in flexion and extension. The Linked Four-Rod condition significantly decreased flexibility in left-right axial rotation compared with the Four-Rod and Linked Two-Rod conditions. No significant differences occurred in relative lateral movement between left and right pelvic polyethylene blocks. Conclusion.: The four-rod technique improved fixation stability over the conventional linked two-rod technique in flexion and extension, and when cross-linked, in left-right axial rotation. The four-rod technique also significantly reduced L5-Pelvic junction movement in flexionand extension, which may have implications for bony fusion. The use of cross-links is recommended.

Original languageEnglish (US)
JournalSpine
Volume33
Issue number13
DOIs
StatePublished - Jun 1 2008

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Spine
Polyethylene
Biomechanical Phenomena
Analysis of Variance
In Vitro Techniques

All Science Journal Classification (ASJC) codes

  • Physiology
  • Clinical Neurology
  • Orthopedics and Sports Medicine

Cite this

Biomechanical testing of a novel four-rod technique for lumbo-pelvic reconstruction. / Kelly, Brian P.; Shen, Francis H.; Schwab, John S.; Arlet, Vincent; Diangelo, Denis.

In: Spine, Vol. 33, No. 13, 01.06.2008.

Research output: Contribution to journalArticle

Kelly, Brian P. ; Shen, Francis H. ; Schwab, John S. ; Arlet, Vincent ; Diangelo, Denis. / Biomechanical testing of a novel four-rod technique for lumbo-pelvic reconstruction. In: Spine. 2008 ; Vol. 33, No. 13.
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abstract = "Study design.: A biomechanical testing protocol was used to study different lumbo-pelvic fixation techniques in a human cadaveric lumbar spine model. Objective.: To compare the in vitro biomechanics of a novel four-rod lumbo-pelvic reconstruction technique with and with out cross-links, to that of a conventional cross-linked two-rod technique. Summary of background data.: Numerous lumbo-pelvic reconstruction methods based on the Galveston two-rod technique have been proposed for cases involving total sacrectomy. Recently a technique that proposes novel use of 4 supporting longitudinal rods across the lumbo-pelvic junction has been reported. No comparative in vitro biomechanical testing has been previously done to evaluate these different reconstruction methods. Methods.: Five spines were evaluated in flexion, extension, left-right lateral bending and left-right axial rotation in a human total sacrectomy model. The model was comprised of cadaveric lumbar spines (L1-L5) with custom fabricated polyethylene blocks used to simulate pelvic fixation. Three conditions were evaluated: Linked Four-Rod, Linked Two-Rod, and Four-Rod (no cross-links). Flexibility and motion data were compared using a one-way repeated measures analysis of variance and SNK tests. Results.: The Linked Four-Rod and Four-Rod conditions significantly decreased flexibility and reduced L5-Pelvic motion over the Linked Two-Rod construct in flexion and extension. The Linked Four-Rod condition significantly decreased flexibility in left-right axial rotation compared with the Four-Rod and Linked Two-Rod conditions. No significant differences occurred in relative lateral movement between left and right pelvic polyethylene blocks. Conclusion.: The four-rod technique improved fixation stability over the conventional linked two-rod technique in flexion and extension, and when cross-linked, in left-right axial rotation. The four-rod technique also significantly reduced L5-Pelvic junction movement in flexionand extension, which may have implications for bony fusion. The use of cross-links is recommended.",
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