Biomechanical and Computed Tomography Analysis of Adjustable Femoral Cortical Fixation Devices for Anterior Cruciate Ligament Reconstruction in a Cadaveric Human Knee Model

Arthroscopy. 2016 Feb;32(2):253-61. doi: 10.1016/j.arthro.2015.11.034.


Purpose: To evaluate and compare two adjustable femoral cortical suspensory fixation devices used for anterior cruciate ligament reconstruction through a novel, direct computed tomography (CT) analysis metric and biomechanical laxity testing in a matched cadaveric human knee study.

Methods: Anterior cruciate ligament reconstructions with bovine tendon grafts were performed using two adjustable femoral cortical suspensory fixation devices (RigidLoop Adjustable [DePuy Synthes Mitek, Raynham, MA] and TightRope [Arthrex, Naples, FL]) in 12 knees (6 matched pairs). A mechanical testing series was used to determine each knee's laxity in the intact condition. After reconstruction, each specimen was again tested for laxity and also imaged with CT. The laxity testing and CT imaging were then repeated after 1,000 cycles of anteroposterior loading on each knee to compare changes in laxity for the two fixation devices and to visualize changes in button-to-graft distance migration through a three-dimensional CT imaging method.

Results: No significant differences were found between the two fixation groups' laxity measures after reconstruction (all P values ≥ .620) or after cycling (all P values ≥ .211) at any flexion angle. In addition, no significant differences were found between the two groups regarding button-to-graft distance migration (P = .773; mean, 0.61 ± 0.6 mm [95% confidence interval, -0.1 to 1.3 mm] in RigidLoop Adjustable group and 0.53 ± 0.6 mm [95% confidence interval, -0.1 to 1.2 mm] in TightRope group).

Conclusions: There were no significant differences between the two femoral cortical suspensory adjustable-loop devices regarding laxity outcomes or loop displacement as measured by button-to-graft distance migration.

Clinical relevance: Use of either of the adjustable-loop cortical suspensory devices in our analysis would appear to produce similar, acceptable laxity outcomes and minimal effects in terms of device-related loop displacement.

MeSH terms

  • Animals
  • Anterior Cruciate Ligament / diagnostic imaging
  • Anterior Cruciate Ligament / physiopathology*
  • Anterior Cruciate Ligament / surgery*
  • Anterior Cruciate Ligament Reconstruction / instrumentation*
  • Anterior Cruciate Ligament Reconstruction / methods
  • Biomechanical Phenomena
  • Cadaver
  • Cattle
  • Female
  • Femur / surgery
  • Humans
  • Internal Fixators*
  • Joint Instability / diagnostic imaging
  • Joint Instability / physiopathology
  • Knee Joint / diagnostic imaging
  • Knee Joint / physiopathology*
  • Knee Joint / surgery*
  • Male
  • Middle Aged
  • Tendons / transplantation*
  • Tomography, X-Ray Computed