Mechanical comparison of biodegradable femoral fixation devices for hamstring tendon graft--a biomechanical study in a porcine model.
BACKGROUND
Initial fixation strength is critical for the early post-operative rehabilitation of patients with anterior cruciate ligament reconstructions. However, even the best femoral fixation devices remain controversial. We compared the biomechanical characteristics of tendon grafts fixed by different biodegradable femoral fixation devices following anterior cruciate ligament reconstruction.


METHODS
The Bio-TransFix, Rigidfix, Bioscrew with EndoPearl augmentation and Bioscrew devices were used to fix porcine flexor digitorum profundus tendon grafts in 32 porcine femora. Displacement of each tendon graft was evaluated after cyclic loading testing. Stiffness, ultimate failure load and failure mode of these fixation devices were measured with load-to-failure testing.


RESULTS
The displacement of the femur-graft-cement complex in response to cyclic loading was lower (P<0.05) for the Bio-TransFix than the Rigidfix, Bioscrew with EndoPearl augmentation, and Bioscrew groups. The fixation stiffness values of the Rigidfix and the Bioscrew were significantly greater (P<0.05) than that of the Bio-TransFix. The ultimate failure load was significantly greater for the Bio-TransFix and the Rigidfix than the Bioscrew with EndoPearl augmentation or the Bioscrew (P<0.05).


CONCLUSIONS
The Bio-TransFix provided the least graft displacement under cyclic loading. However, this device gave less stability. The Rigidfix device provided better stability and stiffness of the tendon graft among those fixation devices that showed no significant differences in graft displacement under cyclic loading. However, no single fixation device provided less displacement along with a larger failure load and stiffness in this study.
Wu
Jia-Lin
JL
Department of Orthopaedic Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. wu.jialin.ortho@gmail.com
Yeh
Tsu-Te
TT
Shen
Hsain-Chung
HC
Cheng
Cheng-Kung
CK
Lee
Chian-Her
CH
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery / Q000637:transplantation; D001672:Biocompatible Materials; D001673:Biodegradation, Environmental; D001696:Biomechanical Phenomena; D004867:Equipment Design; D004868:Equipment Failure; D005269:Femur / Q000473:pathology; D016268:Internal Fixators; D008422:Materials Testing; D019651:Plastic Surgery Procedures / Q000295:instrumentation; D013314:Stress, Mechanical; D013552:Swine; D013718:Tensile Strength
D001672:Biocompatible Materials