title: Mechanical comparison of biodegradable femoral fixation devices for hamstring tendon graft--a biomechanical study in a porcine model.
abstract: 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.
authors.affiliation: Department of Orthopaedic Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. wu.jialin.ortho@gmail.com
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Wu
authors.forename: Tsu-Te
authors.initials: TT
authors.lastname: Yeh
authors.forename: Hsain-Chung
authors.initials: HC
authors.lastname: Shen
authors.forename: Cheng-Kung
authors.initials: CK
authors.lastname: Cheng
authors.forename: Chian-Her
authors.initials: CH
authors.lastname: Lee
mesh_terms: 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
chemical_list: D001672:Biocompatible Materials