Effect of screw length on bioabsorbable interference screw fixation in a tibial bone tunnel

Jeffrey B. Selby, Darren L. Johnson, Peter Hester, David N.M. Caborn

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Initial tibial fixation strength is the weak link after anterior cruciate ligament reconstruction with a quadrupled hamstring tendon graft fixed with bioabsorbable interference screws. The purpose of this study was to determine the biomechanical differences between 28-mm and tapered 35-mm interference screws for tibial fixation of a soft tissue graft in 16 young cadaveric tibias. Failure mode, displacement before failure, and ultimate failure load were tested with a testing machine aligned with the tibial tunnel to simulate a worst-case scenario. The mode of failure was graft slippage past the screw in all but one of the specimens. The mean maximum load at failure of the 28-mm screw was 594.9 ± 141.0 N, with mean displacement at failure of 10.97 ± 2.20 mm. The mean maximum load at failure of the 35-mm screw was 824.9 ± 124.3 N, with a mean displacement to failure of 14.38 ± 2.15 mm. The 38% difference in mean maximal load at failure was significant. Important variables in hamstring tendon graft fixation within a bone tunnel include bone mineral density, dilatation, gap size, screw placement, and screw width and length. Attention to these variables will help to provide secure graft fixation during biologic incorporation throughout the rehabilitation period.

Original languageEnglish
Pages (from-to)614-619
Number of pages6
JournalAmerican Journal of Sports Medicine
Issue number5
StatePublished - 2001

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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