Hamstring graft motion in the femoral bone tunnel when using titanium button/polyester tape fixation

The objective of this study was to determine the relative motion of a quadr uple hamstring graft within the femoral bone tunnel (graft-tunnel motion) u nder tensile loading. Six graft constructs were prepared from the semitendi nosus and,oracilis tendons of human cadavers and were fixed with a titanium button and polyester tape within a bone tunnel in a cadaveric femur. Three different lengths of polyester tape (15, 25, and 35 mm loops) were evaluat ed. The femur was held stationary and uniaxial tensile loads were applied t o the distal end of the graft using a materials testing machine. Each const ruct was subjected to loading for ten cycles with upper limits of 50 N, 100 N, 200 N and 300 N. Graft-tunnel motion was then determined using the dist ances between reflective tape markers placed on the hamstring graft and at the entrance to the femoral bone tunnel, which were tracked with a high-res olution video system. Graft-tunnel motion was found to range from 0.7 +/- 0 .2 mm to 3.3 +/- 0.2 mm, and significant increases in graft-tunnel motion w ere observed with increasing tensile loads (P < 0.05). Shorter tape length (15 mm) resulted in significantly less motion when compared to longer tape length (35 mm) (P < 0.05). We conclude that graft-tunnel motion is signific ant and should be considered when using this fixation technique. Early stre ss on the graft, as seen in postoperative rehabilitation exercises and athl etic activities, may cause large graft-tunnel motion before graft incorpora tion is complete. A shorter distance between the tendon tissue and the tita nium button is recommended to minimize the amount of graft-tunnel motion. A lternative fixation materials to polyester tape, or different fixation tech niques, need to be developed such that graft-tunnel motion can be reduced. Further studies are needed to evaluate the effect of graft-tunnel motion on graft incorporation in the bone tunnel.