Abstract
The aim was to compare the initial pull out strengths of various interference screw devices used for tibial fixation of hamstring grafts and the effect of concentric or eccentric screw position.
Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix, RCI screw, Wedge screw +/− transfix pin, screw and post) in both concentric and eccentric positions. A single load to failure test was then performed.
The highest pull out strength was with the Intrafix device inserted concentrically (mean 941N). This was significantly higher than the wedge screw inserted concentrically (737N) (p=0.015). This in turn had significantly greater initial pull out strength than the wedge eccentric with post or pin (p=0.03) and the RCI screw (464N) (p=0.00036).
In this sheep model the Intrafix device inserted concentrically had a significantly greater initial pull-out strength than the other interference screws tested. Concentric positioning of an interference screw gave significantly greater initial pullout strength of a quadruple hamstring graft than eccentric positioning. Addition of a cross pin or post made no difference to initial pullout strength.
The abstracts were prepared by Editorial Secretary Jean-Claude Theis. Correspondence should be addressed to NZOA at Department of Orthopaedic Surgery, Dunedin Hospital, Private Bag 1921, Dunedin, New Zealand.
