How four weeks of implantation affect the strength and stiffness of a tendon graft in a bone tunnel: a study of two fixation devices in an extraarticular model in ovine.
BACKGROUND
For a tendon graft to function as an anterior cruciate ligament, the tendon must heal to the bone tunnel. We studied the effect of 4 weeks of implantation on the strength and stiffness of a tendon in a bone tunnel using two different fixation devices in an ovine model.


OBJECTIVE
The type of fixation device in anterior cruciate ligament reconstruction may affect early healing, which can be measured as the strength and stiffness of a tendon in a bone tunnel.


METHODS
Controlled laboratory study.


METHODS
An extraarticular tendon graft reconstruction was performed in ovine tibias. The graft was fixed with either a bioresorbable interference screw or a WasherLoc. After 4 weeks of implantation the strength and stiffness of the complex and the tendon graft-bone tunnel interface were determined by incrementally loading specimens to failure.


RESULTS
For the interference screw, the strength deteriorated 63% and the stiffness deteriorated 40%. For the WasherLoc, the strength was similar and the stiffness improved 136%.


CONCLUSIONS
The type of fixation device determines whether the strength and stiffness of a tendon in a bone tunnel increases or decreases after implantation.


CONCLUSIONS
The pace of rehabilitation may need to be adjusted based on the type of fixation device used to secure a soft tissue graft.
Singhatat
Wamis
W
Biomedical Engineering Graduate Group, University of California at Davis, Davis, California 95823, USA.
Lawhorn
Keith W
KW
Howell
Stephen M
SM
Hull
Maury L
ML
D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D004195:Disease Models, Animal; D008422:Materials Testing; D009984:Orthopedic Fixation Devices; D011897:Random Allocation; D012756:Sheep; D013710:Tendons / Q000637:transplantation*; D013997:Time Factors; D014945:Wound Healing