Anterior cruciate ligament fixation: is radial force a predictor of the pullout strength of soft-tissue interference devices?


Journal Article

BACKGROUND: In anterior cruciate ligament (ACL) reconstruction, an interference device achieves soft-tissue graft fixation by radially compressing the graft against the bone. PURPOSE: The objective of this study was to measure the radial force generated by different interference devices and evaluate the effect of this radial force on the pullout strength of graft-device constructs. STUDY DESIGN: Controlled laboratory study. METHODS: A resultant force (F(R)) was used as a representative measure of the total radial force generated. Bovine tendons were fixated in either synthetic bone or porcine tibia using one of following devices: (1) RCI titanium screw, (2) PEEK screw, (3) IntraFix sheath-and-screw device, and (4) ExoShape sheath-and-insert device. F(R) was measured while each device was inserted into synthetic bone mounted on a test machine (n=5 for each device). In a subsequent test series, graft-device constructs were loaded to failure at 50mm/min. The pullout strength was measured as the ultimate load before failure (n=10 for each device). RESULTS: The F(R) values generated during insertion into synthetic bone were 777 ± 86N, 865 ± 140N, 1313 ± 198N, and 1780 ± 255N for the RCI screw, PEEK screw, IntraFix, and ExoShape, respectively. The pullout strengths in synthetic bone for the RCI screw, PEEK screw, IntraFix and ExoShape were 883 ± 125N, 716 ± 249N, 1147 ± 142N, and 1233 ± 190N, respectively. CONCLUSIONS: These results suggest that the F(R) generated during interference fixation affects the pullout strength with sheath-based devices providing superior F(R) compared with interference screws. The use of synthetic bone was validated by comparing the pullout strengths to those when tested in porcine tibia. CLINICAL RELEVANCE: These results could be valuable to a surgeon when determining the best fixation device to use in the clinical setting.

Full Text

Duke Authors

Cited Authors

  • Smith, KE; Garcia, M; McAnuff, K; Lamell, R; Yakacki, CM; Griffis, J; Higgs, GB; Gall, K

Published Date

  • December 2012

Published In

Volume / Issue

  • 19 / 6

Start / End Page

  • 786 - 792

PubMed ID

  • 22439980

Pubmed Central ID

  • 22439980

Electronic International Standard Serial Number (EISSN)

  • 1873-5800

International Standard Serial Number (ISSN)

  • 0968-0160

Digital Object Identifier (DOI)

  • 10.1016/j.knee.2012.02.008


  • eng