Spinal instrumentation for sacral-pelvic fixation: A biomechanical comparison between constructs ending with either S2 bicortical, bitriangulated screws or iliac screws

Jin Hwan Kim, William Horton, Takahiko Hamasaki, Brett Freedman, Thomas E. Whitesides, William C. Hutton

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Study design: A biomechanical study of 2 fixation techniques for lumbosacral fixation. Objective: To evaluate 2 techniques, one using S1 screws combined with bicortical, bitriangulated (BCBT) S2 screws, and the other using S1 screws combined with iliac screws. Summary of background data: Common to the 2 techniques of sacral-pelvic fixation is S1 pedicle screws; the difference lies between S2 screws versus iliac screws. Iliac screws are clinically effective, yet present clinical disadvantages that S2 screws can potentially obviate, for example, wide dissection, soft tissue coverage, crossing the sacroiliac joint, and interference with bone graft harvesting. In an effort to optimize S2 fixation, we have used a BCBT S2 technique. Methods: Eight fresh human sacral-pelvic specimens were harvested (average age 78.7 y; bone density 0.75 g/cm). Screws were placed bilaterally: (1) at S1: 7.5 mm diameter screws were placed bicortical; (2) at S2: 7.5 mm diameter by 60 mm long screws were placed bicortical and bitriangulated; (3) the ilium received 7.5 mm diameter by 80-mm-long screws. Sacral-pelvic constructs were assembled and biomechanical stiffness testing was performed. The stiffness in each loading mode was calculated. After the stiffness tests were completed, each BCBT S2 screw and each iliac screw were individually loaded to determine fixation strength of each type of screw. Results: There was no significant difference in stiffness between the 2 constructs, although S1 and the BCBT S2 construct tended to be stiffer in all modes. However, for the fixation strength of screws, the iliac screws loosened at loads that were significantly greater than those for BCBT S2 screws (c.f. 435.9 N with 144.7 N). Conclusions: Iliac screws maybe the better choice in cases with poor bone quality. However, the S1-BCBT-S2 screw construct is biomechanically an appropriate alternative to the S1-iliac screw construct and it presents clinical advantages.

Original languageEnglish (US)
Pages (from-to)506-512
Number of pages7
JournalJournal of Spinal Disorders and Techniques
Volume23
Issue number8
DOIs
StatePublished - Dec 1 2010
Externally publishedYes

Fingerprint

Ilium
Sacroiliac Joint
Bone and Bones
Bone Density
Dissection
Transplants
Pedicle Screws

Keywords

  • biomechanics
  • iliac screws
  • S2 screws
  • sacral-pelvic fixation
  • spine

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine
  • Clinical Neurology

Cite this

Spinal instrumentation for sacral-pelvic fixation : A biomechanical comparison between constructs ending with either S2 bicortical, bitriangulated screws or iliac screws. / Kim, Jin Hwan; Horton, William; Hamasaki, Takahiko; Freedman, Brett; Whitesides, Thomas E.; Hutton, William C.

In: Journal of Spinal Disorders and Techniques, Vol. 23, No. 8, 01.12.2010, p. 506-512.

Research output: Contribution to journalArticle

@article{8f685c45868d40468b1947ba5d309317,
title = "Spinal instrumentation for sacral-pelvic fixation: A biomechanical comparison between constructs ending with either S2 bicortical, bitriangulated screws or iliac screws",
abstract = "Study design: A biomechanical study of 2 fixation techniques for lumbosacral fixation. Objective: To evaluate 2 techniques, one using S1 screws combined with bicortical, bitriangulated (BCBT) S2 screws, and the other using S1 screws combined with iliac screws. Summary of background data: Common to the 2 techniques of sacral-pelvic fixation is S1 pedicle screws; the difference lies between S2 screws versus iliac screws. Iliac screws are clinically effective, yet present clinical disadvantages that S2 screws can potentially obviate, for example, wide dissection, soft tissue coverage, crossing the sacroiliac joint, and interference with bone graft harvesting. In an effort to optimize S2 fixation, we have used a BCBT S2 technique. Methods: Eight fresh human sacral-pelvic specimens were harvested (average age 78.7 y; bone density 0.75 g/cm). Screws were placed bilaterally: (1) at S1: 7.5 mm diameter screws were placed bicortical; (2) at S2: 7.5 mm diameter by 60 mm long screws were placed bicortical and bitriangulated; (3) the ilium received 7.5 mm diameter by 80-mm-long screws. Sacral-pelvic constructs were assembled and biomechanical stiffness testing was performed. The stiffness in each loading mode was calculated. After the stiffness tests were completed, each BCBT S2 screw and each iliac screw were individually loaded to determine fixation strength of each type of screw. Results: There was no significant difference in stiffness between the 2 constructs, although S1 and the BCBT S2 construct tended to be stiffer in all modes. However, for the fixation strength of screws, the iliac screws loosened at loads that were significantly greater than those for BCBT S2 screws (c.f. 435.9 N with 144.7 N). Conclusions: Iliac screws maybe the better choice in cases with poor bone quality. However, the S1-BCBT-S2 screw construct is biomechanically an appropriate alternative to the S1-iliac screw construct and it presents clinical advantages.",
keywords = "biomechanics, iliac screws, S2 screws, sacral-pelvic fixation, spine",
author = "Kim, {Jin Hwan} and William Horton and Takahiko Hamasaki and Brett Freedman and Whitesides, {Thomas E.} and Hutton, {William C.}",
year = "2010",
month = "12",
day = "1",
doi = "10.1097/BSD.0b013e3181c37438",
language = "English (US)",
volume = "23",
pages = "506--512",
journal = "Journal of Spinal Disorders",
issn = "1536-0652",
publisher = "Lippincott Williams and Wilkins",
number = "8",

}

TY - JOUR

T1 - Spinal instrumentation for sacral-pelvic fixation

T2 - A biomechanical comparison between constructs ending with either S2 bicortical, bitriangulated screws or iliac screws

AU - Kim, Jin Hwan

AU - Horton, William

AU - Hamasaki, Takahiko

AU - Freedman, Brett

AU - Whitesides, Thomas E.

AU - Hutton, William C.

PY - 2010/12/1

Y1 - 2010/12/1

N2 - Study design: A biomechanical study of 2 fixation techniques for lumbosacral fixation. Objective: To evaluate 2 techniques, one using S1 screws combined with bicortical, bitriangulated (BCBT) S2 screws, and the other using S1 screws combined with iliac screws. Summary of background data: Common to the 2 techniques of sacral-pelvic fixation is S1 pedicle screws; the difference lies between S2 screws versus iliac screws. Iliac screws are clinically effective, yet present clinical disadvantages that S2 screws can potentially obviate, for example, wide dissection, soft tissue coverage, crossing the sacroiliac joint, and interference with bone graft harvesting. In an effort to optimize S2 fixation, we have used a BCBT S2 technique. Methods: Eight fresh human sacral-pelvic specimens were harvested (average age 78.7 y; bone density 0.75 g/cm). Screws were placed bilaterally: (1) at S1: 7.5 mm diameter screws were placed bicortical; (2) at S2: 7.5 mm diameter by 60 mm long screws were placed bicortical and bitriangulated; (3) the ilium received 7.5 mm diameter by 80-mm-long screws. Sacral-pelvic constructs were assembled and biomechanical stiffness testing was performed. The stiffness in each loading mode was calculated. After the stiffness tests were completed, each BCBT S2 screw and each iliac screw were individually loaded to determine fixation strength of each type of screw. Results: There was no significant difference in stiffness between the 2 constructs, although S1 and the BCBT S2 construct tended to be stiffer in all modes. However, for the fixation strength of screws, the iliac screws loosened at loads that were significantly greater than those for BCBT S2 screws (c.f. 435.9 N with 144.7 N). Conclusions: Iliac screws maybe the better choice in cases with poor bone quality. However, the S1-BCBT-S2 screw construct is biomechanically an appropriate alternative to the S1-iliac screw construct and it presents clinical advantages.

AB - Study design: A biomechanical study of 2 fixation techniques for lumbosacral fixation. Objective: To evaluate 2 techniques, one using S1 screws combined with bicortical, bitriangulated (BCBT) S2 screws, and the other using S1 screws combined with iliac screws. Summary of background data: Common to the 2 techniques of sacral-pelvic fixation is S1 pedicle screws; the difference lies between S2 screws versus iliac screws. Iliac screws are clinically effective, yet present clinical disadvantages that S2 screws can potentially obviate, for example, wide dissection, soft tissue coverage, crossing the sacroiliac joint, and interference with bone graft harvesting. In an effort to optimize S2 fixation, we have used a BCBT S2 technique. Methods: Eight fresh human sacral-pelvic specimens were harvested (average age 78.7 y; bone density 0.75 g/cm). Screws were placed bilaterally: (1) at S1: 7.5 mm diameter screws were placed bicortical; (2) at S2: 7.5 mm diameter by 60 mm long screws were placed bicortical and bitriangulated; (3) the ilium received 7.5 mm diameter by 80-mm-long screws. Sacral-pelvic constructs were assembled and biomechanical stiffness testing was performed. The stiffness in each loading mode was calculated. After the stiffness tests were completed, each BCBT S2 screw and each iliac screw were individually loaded to determine fixation strength of each type of screw. Results: There was no significant difference in stiffness between the 2 constructs, although S1 and the BCBT S2 construct tended to be stiffer in all modes. However, for the fixation strength of screws, the iliac screws loosened at loads that were significantly greater than those for BCBT S2 screws (c.f. 435.9 N with 144.7 N). Conclusions: Iliac screws maybe the better choice in cases with poor bone quality. However, the S1-BCBT-S2 screw construct is biomechanically an appropriate alternative to the S1-iliac screw construct and it presents clinical advantages.

KW - biomechanics

KW - iliac screws

KW - S2 screws

KW - sacral-pelvic fixation

KW - spine

UR - http://www.scopus.com/inward/record.url?scp=78650385318&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78650385318&partnerID=8YFLogxK

U2 - 10.1097/BSD.0b013e3181c37438

DO - 10.1097/BSD.0b013e3181c37438

M3 - Article

C2 - 20124912

AN - SCOPUS:78650385318

VL - 23

SP - 506

EP - 512

JO - Journal of Spinal Disorders

JF - Journal of Spinal Disorders

SN - 1536-0652

IS - 8

ER -