High-stiffness distal fixation restores anterior laxity and stiffness as well as joint line fixation with an interference screw
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Published on: May 20, 2019
David Liu-Barba1, Stephen M Howell, Maury L Hull
1Department of Mechanical Engineering, University of California at Davis, Davis, California, USA.
Background:
Fixation of an anterior cruciate ligament graft at the joint line with an interference screw restores anterior laxity better than low-stiffness distal fixation with double staples and sutures tied to a post at implantation in porcine bone.
Hypothesis:
Fixation of an anterior cruciate ligament graft with a high-stiffness distal fixation device restores anterior laxity and knee stiffness as well as joint line fixation with an interference screw in human bone.
Study Design:
Controlled laboratory study.
Methods:
Eleven cadaveric knees with foam reinforcement of the bone were reconstructed with a double-looped tendon graft and fixed with an interference screw and 3 high-stiffness methods of fixation (tandem washer, WasherLoc, and WasherLoc with bone dowel). Anterior laxity at 225 and 110 N of anterior load and knee stiffness were measured at 0 degrees , 30 degrees , 60 degrees , 90 degrees , and 120 degrees of flexion with a 6 degrees of freedom load application system.
Results:
The increase in anterior laxity and knee stiffness with the interference screw was not significantly different from that with the high-stiffness distal methods.
Conclusion:
In the human knee, the use of high-stiffness fixation devices placed distal to the joint line restored anterior laxity and knee stiffness as well as joint line fixation with an interference screw at implantation.
Clinical Relevance:
The stiffness provided by each method of fixation should be considered along with the length of the graft when determining anterior laxity and knee stiffness.
