title: Components of laxity in interference fit fixation of quadrupled hamstring grafts.
abstract: We tested in vitro 15 Poly-L-lactic acid and 14 titanium interference screws in male human cadaver tibia-hamstring constructs. Elongation of the graft, displacement of the screw in the tibial tunnel, and slippage at the graft/screw interface were measured as outcomes with an infrared optical system. All constructs failed by slippage of the graft past the interference screw. On average, graft slippage accounted for 92% of total construct laxity at 5mm total construct elongation, whereas permanent stretching of the midsubstance of the graft accounted for only 8%. Movement of the interference screw in the tibial canal was minimal, averaging 0.01 (0-0.5) mm at construct failure. Inadequacy of isolated tibial interference screw fixation of soft tissue grafts may be overcome if early failure at the graft/screw interface is prevented.
authors.affiliation: Baylor Sports Medicine Institute, Institute of Orthopedic Research, Barnhart Department of Orthopedic Surgery, Baylor College of Medicine, Houston, Texas, USA. merittmeister@aol.com
authors.forename: Markus E
authors.initials: ME
authors.lastname: Rittmeister
authors.forename: Philipp C
authors.initials: PC
authors.lastname: Noble
authors.forename: James R
authors.initials: JR
authors.lastname: Bocell
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Alexander
authors.forename: Michael A
authors.initials: MA
authors.lastname: Conditt
authors.forename: Harold W
authors.initials: HW
authors.lastname: Kohl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D016001:Confidence Intervals; D006085:Graft Survival; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000601:surgery; D011091:Polyesters; D011336:Probability; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013718:Tensile Strength; D016378:Tissue Transplantation / Q000379:methods*; D014025:Titanium
chemical_list: D011091:Polyesters; C033616:poly(lactide); D014025:Titanium