Biomechanical comparison of occipitoatlantal screw fixation techniques: Laboratory investigation

Nicholas C. Bambakidis, Iman Feiz-Erfan, Eric Horn, L. Fernando Gonzalez, Seungwon Baek, K. Zafer Yüksel, Anna G U Brantley, Volker K H Sonntag, Neil R. Crawford

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Object. The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. Methods. Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. Results. Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p <0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. Conclusions. Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.

Original languageEnglish (US)
Pages (from-to)143-152
Number of pages10
JournalJournal of Neurosurgery: Spine
Volume8
Issue number2
DOIs
StatePublished - Feb 2008
Externally publishedYes

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Fatigue
Transplants
Articular Range of Motion
Skull Base
Direction compound

Keywords

  • Atlas
  • Axis
  • Biomechanics
  • Cable/graft fixation
  • Occiput
  • Screw/rod fixation

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery
  • Neurology

Cite this

Bambakidis, N. C., Feiz-Erfan, I., Horn, E., Gonzalez, L. F., Baek, S., Yüksel, K. Z., ... Crawford, N. R. (2008). Biomechanical comparison of occipitoatlantal screw fixation techniques: Laboratory investigation. Journal of Neurosurgery: Spine, 8(2), 143-152. https://doi.org/10.3171/SPI/2008/8/2/143

Biomechanical comparison of occipitoatlantal screw fixation techniques : Laboratory investigation. / Bambakidis, Nicholas C.; Feiz-Erfan, Iman; Horn, Eric; Gonzalez, L. Fernando; Baek, Seungwon; Yüksel, K. Zafer; Brantley, Anna G U; Sonntag, Volker K H; Crawford, Neil R.

In: Journal of Neurosurgery: Spine, Vol. 8, No. 2, 02.2008, p. 143-152.

Research output: Contribution to journalArticle

Bambakidis, NC, Feiz-Erfan, I, Horn, E, Gonzalez, LF, Baek, S, Yüksel, KZ, Brantley, AGU, Sonntag, VKH & Crawford, NR 2008, 'Biomechanical comparison of occipitoatlantal screw fixation techniques: Laboratory investigation', Journal of Neurosurgery: Spine, vol. 8, no. 2, pp. 143-152. https://doi.org/10.3171/SPI/2008/8/2/143
Bambakidis, Nicholas C. ; Feiz-Erfan, Iman ; Horn, Eric ; Gonzalez, L. Fernando ; Baek, Seungwon ; Yüksel, K. Zafer ; Brantley, Anna G U ; Sonntag, Volker K H ; Crawford, Neil R. / Biomechanical comparison of occipitoatlantal screw fixation techniques : Laboratory investigation. In: Journal of Neurosurgery: Spine. 2008 ; Vol. 8, No. 2. pp. 143-152.
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abstract = "Object. The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. Methods. Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. Results. Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3{\%} of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p <0.02), reducing ROM to 17{\%} of normal. The wired contoured rod reduced motion to 31{\%} of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26{\%}, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. Conclusions. Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.",
keywords = "Atlas, Axis, Biomechanics, Cable/graft fixation, Occiput, Screw/rod fixation",
author = "Bambakidis, {Nicholas C.} and Iman Feiz-Erfan and Eric Horn and Gonzalez, {L. Fernando} and Seungwon Baek and Y{\"u}ksel, {K. Zafer} and Brantley, {Anna G U} and Sonntag, {Volker K H} and Crawford, {Neil R.}",
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AU - Bambakidis, Nicholas C.

AU - Feiz-Erfan, Iman

AU - Horn, Eric

AU - Gonzalez, L. Fernando

AU - Baek, Seungwon

AU - Yüksel, K. Zafer

AU - Brantley, Anna G U

AU - Sonntag, Volker K H

AU - Crawford, Neil R.

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N2 - Object. The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. Methods. Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. Results. Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p <0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. Conclusions. Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.

AB - Object. The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. Methods. Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. Results. Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p <0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. Conclusions. Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.

KW - Atlas

KW - Axis

KW - Biomechanics

KW - Cable/graft fixation

KW - Occiput

KW - Screw/rod fixation

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