title: Initial fixation strength of a hybrid technique for femoral ACL graft fixation.
abstract: Aperture fixation with interference screws matching the diameter of the tunnel is associated with the risk of graft laceration and graft rotation. A hybrid fixation technique (extracortical and aperture fixation) with undersized interference screws provides a higher fixation strength when compared to an aperture fixation using only a screw matching the size of the tunnel and also reduces the risk of graft laceration. This research is an experimental laboratory study. We evaluated the initial fixation strength at time-zero of an extracortical-, a hybrid- and an aperture fixation in ACL reconstruction using extracortical buttons and different sized interference screws in porcine knees. The tests were performed using a single cycle and cyclic loading protocol. Analysis of yield load, maximum load and stiffness in the single cycle loading test showed no statistically significant differences for hybrid fixation with a 1 mm undersized screw and aperture fixation with a screw matching the size of the tunnel. Cyclic loading tests showed a statistically significant difference between hybrid and aperture fixation. The use of an undersized screw alone in aperture fixation resulted in insufficient fixation strength. The initial fixation strength of the hybrid technique with undersized screws is higher compared to an interference screw fixation alone. The hybrid fixation technique is an alternative for ACL graft fixation.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, Westphalian-Wilhelms-University Muenster, Waldeyerstr 1, 48149 Muenster, Germany.
authors.forename: Andre
authors.initials: A
authors.lastname: Weimann
authors.forename: Thore
authors.initials: T
authors.lastname: Zantop
authors.forename: Mirco
authors.initials: M
authors.lastname: Herbort
authors.forename: Michael
authors.initials: M
authors.lastname: Strobel
authors.forename: Wolf
authors.initials: W
authors.lastname: Petersen
mesh_terms: D020341:Absorbable Implants / Q000009:adverse effects; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws / Q000009:adverse effects; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005269:Femur / Q000601:surgery*; D008422:Materials Testing; D019637:Orthopedic Procedures / Q000379:methods*; D013552:Swine; D013718:Tensile Strength / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology