Interference screw fixation of cervical grafts: A combined in vitro biomechanical and in vivo animal study

P. Vazquez-Seoane, Jung Yoo, D. Zou, L. A. Fay, B. E. Fredrickson, J. C. Handal, H. A. Yuan, W. T. Edwards

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference Screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadavor cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 53.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N);and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four- 3.5 mm screw constructs were significantly greater than the strength of the graft alone(P<0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a singie-level anterior cervical discectomy and fusion were performed on 20 sheep. The fixation was augmented i n ten following surgery. At the end of 12 weeks, all nondisplaced cervical graft/vertebra constructs were harvested, radiographs were taken, and histology was performed. A very high rate of cervical graft dislodgement was found in this sheep model of anterior cervical fusion. The graft survival curve demonstrates that, for both groups, the high-risk period of graft dislodgement is during the first week following surgery. There was statistically-improved graft survival at 1, 2, 6, and 12 Weeks for the grafts augmented with interference screws compared with that seen in the control group (P<0.04). All nondisplaced grafts resulted in solid fusion by observed in direct visual examination, roentgenogram, and histology of the specimen. No adverse effect to graft incorporation was found for the interference screw group. This study demonstrates that interference screw fixation augments the stability of the anterior bone graft construct and decreases the dislodgement following anterior cervical grafting without compromising the graft incorporation.

Original languageEnglish (US)
Pages (from-to)946-954
Number of pages9
JournalSpine
Volume18
Issue number8
StatePublished - 1993
Externally publishedYes

Fingerprint

Transplants
Bone and Bones
Diskectomy
Sheep
Spine
In Vitro Techniques
Graft Survival
Histology
Bone Screws
Cervical Vertebrae
Control Groups

Keywords

  • Animal studyl
  • Cervical spine
  • Discectomy graft
  • Graft migration
  • Interference screw fixation

ASJC Scopus subject areas

  • Clinical Neurology
  • Orthopedics and Sports Medicine
  • Physiology

Cite this

Vazquez-Seoane, P., Yoo, J., Zou, D., Fay, L. A., Fredrickson, B. E., Handal, J. C., ... Edwards, W. T. (1993). Interference screw fixation of cervical grafts: A combined in vitro biomechanical and in vivo animal study. Spine, 18(8), 946-954.

Interference screw fixation of cervical grafts : A combined in vitro biomechanical and in vivo animal study. / Vazquez-Seoane, P.; Yoo, Jung; Zou, D.; Fay, L. A.; Fredrickson, B. E.; Handal, J. C.; Yuan, H. A.; Edwards, W. T.

In: Spine, Vol. 18, No. 8, 1993, p. 946-954.

Research output: Contribution to journalArticle

Vazquez-Seoane, P, Yoo, J, Zou, D, Fay, LA, Fredrickson, BE, Handal, JC, Yuan, HA & Edwards, WT 1993, 'Interference screw fixation of cervical grafts: A combined in vitro biomechanical and in vivo animal study', Spine, vol. 18, no. 8, pp. 946-954.
Vazquez-Seoane P, Yoo J, Zou D, Fay LA, Fredrickson BE, Handal JC et al. Interference screw fixation of cervical grafts: A combined in vitro biomechanical and in vivo animal study. Spine. 1993;18(8):946-954.
Vazquez-Seoane, P. ; Yoo, Jung ; Zou, D. ; Fay, L. A. ; Fredrickson, B. E. ; Handal, J. C. ; Yuan, H. A. ; Edwards, W. T. / Interference screw fixation of cervical grafts : A combined in vitro biomechanical and in vivo animal study. In: Spine. 1993 ; Vol. 18, No. 8. pp. 946-954.
@article{c6d03bf4f3d747aba13748d9946fbdbf,
title = "Interference screw fixation of cervical grafts: A combined in vitro biomechanical and in vivo animal study",
abstract = "The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference Screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadavor cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 53.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N);and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four- 3.5 mm screw constructs were significantly greater than the strength of the graft alone(P<0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a singie-level anterior cervical discectomy and fusion were performed on 20 sheep. The fixation was augmented i n ten following surgery. At the end of 12 weeks, all nondisplaced cervical graft/vertebra constructs were harvested, radiographs were taken, and histology was performed. A very high rate of cervical graft dislodgement was found in this sheep model of anterior cervical fusion. The graft survival curve demonstrates that, for both groups, the high-risk period of graft dislodgement is during the first week following surgery. There was statistically-improved graft survival at 1, 2, 6, and 12 Weeks for the grafts augmented with interference screws compared with that seen in the control group (P<0.04). All nondisplaced grafts resulted in solid fusion by observed in direct visual examination, roentgenogram, and histology of the specimen. No adverse effect to graft incorporation was found for the interference screw group. This study demonstrates that interference screw fixation augments the stability of the anterior bone graft construct and decreases the dislodgement following anterior cervical grafting without compromising the graft incorporation.",
keywords = "Animal studyl, Cervical spine, Discectomy graft, Graft migration, Interference screw fixation",
author = "P. Vazquez-Seoane and Jung Yoo and D. Zou and Fay, {L. A.} and Fredrickson, {B. E.} and Handal, {J. C.} and Yuan, {H. A.} and Edwards, {W. T.}",
year = "1993",
language = "English (US)",
volume = "18",
pages = "946--954",
journal = "Spine",
issn = "0362-2436",
publisher = "Lippincott Williams and Wilkins",
number = "8",

}

TY - JOUR

T1 - Interference screw fixation of cervical grafts

T2 - A combined in vitro biomechanical and in vivo animal study

AU - Vazquez-Seoane, P.

AU - Yoo, Jung

AU - Zou, D.

AU - Fay, L. A.

AU - Fredrickson, B. E.

AU - Handal, J. C.

AU - Yuan, H. A.

AU - Edwards, W. T.

PY - 1993

Y1 - 1993

N2 - The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference Screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadavor cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 53.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N);and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four- 3.5 mm screw constructs were significantly greater than the strength of the graft alone(P<0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a singie-level anterior cervical discectomy and fusion were performed on 20 sheep. The fixation was augmented i n ten following surgery. At the end of 12 weeks, all nondisplaced cervical graft/vertebra constructs were harvested, radiographs were taken, and histology was performed. A very high rate of cervical graft dislodgement was found in this sheep model of anterior cervical fusion. The graft survival curve demonstrates that, for both groups, the high-risk period of graft dislodgement is during the first week following surgery. There was statistically-improved graft survival at 1, 2, 6, and 12 Weeks for the grafts augmented with interference screws compared with that seen in the control group (P<0.04). All nondisplaced grafts resulted in solid fusion by observed in direct visual examination, roentgenogram, and histology of the specimen. No adverse effect to graft incorporation was found for the interference screw group. This study demonstrates that interference screw fixation augments the stability of the anterior bone graft construct and decreases the dislodgement following anterior cervical grafting without compromising the graft incorporation.

AB - The dislodgement of an anterior bone graft in the cervical spine is a frequent complication of attempted fusion following discectomy or corpectomy. It has been hypothesized that fixation augmented with interference Screws may increase the pullout strength of the construct and decrease the rate of these complications. In vitro mechanical tests and in vivo sheep studies were conducted to compare interference screw fixation methods for enhancing the fixation between the bone graft and the adjacent vertebra. Using human cadavor cervical spines, the anterior pullout strengths of cervical bone grafts were compared using fixation with and without the addition of interference screws for the in vitro mechanical testing. The mean pullout forces for a Smith-Robinson type bone graft alone was 53.1 N (SD 11.4 N); for the graft augmented with two 3.5 mm cancellous bone screws, 153.9 N (58.9 N);and for the graft with four 3.5 mm screws, 217.1 N (SD 69.9 N). The pullout strengths of the two- and four- 3.5 mm screw constructs were significantly greater than the strength of the graft alone(P<0.05). Similarly placed 2.7 mm cortical screws of the same length provided increased pullout strength (123.7 N 38.6 N and 142.5N 38.2 N for two- and four-screw constructs, respectively); however, in comparison to the graft alone, these differences were not statistically significant. For both screw types, the four-screw fixations were stronger than the two-screw fixations, although these differences were not statistically significant. For the in vivo portion of the study, a singie-level anterior cervical discectomy and fusion were performed on 20 sheep. The fixation was augmented i n ten following surgery. At the end of 12 weeks, all nondisplaced cervical graft/vertebra constructs were harvested, radiographs were taken, and histology was performed. A very high rate of cervical graft dislodgement was found in this sheep model of anterior cervical fusion. The graft survival curve demonstrates that, for both groups, the high-risk period of graft dislodgement is during the first week following surgery. There was statistically-improved graft survival at 1, 2, 6, and 12 Weeks for the grafts augmented with interference screws compared with that seen in the control group (P<0.04). All nondisplaced grafts resulted in solid fusion by observed in direct visual examination, roentgenogram, and histology of the specimen. No adverse effect to graft incorporation was found for the interference screw group. This study demonstrates that interference screw fixation augments the stability of the anterior bone graft construct and decreases the dislodgement following anterior cervical grafting without compromising the graft incorporation.

KW - Animal studyl

KW - Cervical spine

KW - Discectomy graft

KW - Graft migration

KW - Interference screw fixation

UR - http://www.scopus.com/inward/record.url?scp=0027213269&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027213269&partnerID=8YFLogxK

M3 - Article

C2 - 8367782

AN - SCOPUS:0027213269

VL - 18

SP - 946

EP - 954

JO - Spine

JF - Spine

SN - 0362-2436

IS - 8

ER -