title: Biomechanical comparison of osteoporotic distal radius fractures fixed by distal locking screws with different length.
abstract: OBJECTIVE
  To evaluate the postoperative stability of osteoporotic distal radius fractures fixed with distal locking screws with different length.
  
  
  METHODS
  A comminuted extra-articular dorsally unstable distal radius fracture, treated with volar locking plate system, was created. The 18 specimens were randomized into 3 groups based on distal locked screws with different length: Group A had unicortical screws with 50% length to the dorsal cortex. Group B had unicortical screws with 75% length to the dorsal cortex. Group C had bicortical screws. Axial compression and bending loads were imposed on the models before and after cycling testing as well as load to clinical and catastrophic failure.
  
  
  RESULTS
  Minimum change in stiffness was observed before and after fatigue for all groups. The final stiffness to bending forces was statistically similar in all groups, but stiffness to axial compression was statistically significant different: Group A approached significance with respect to groups B and C (P = 0.017, 0.009), whereas stiffness in group B and C was statistically similar (P = 0.93). Load to clinical failure was significantly less for group A (456.54±78.59 N) compared with groups B (580.24±73.85 N) and C (591.07±38.40 N). Load to catastrophic failure was statistically similar between groups, but mean values for Group A were 18% less than means for Group C.
  
  
  CONCLUSIONS
  The volar locking plate system fixed with unicortical locking screws with at least 75% length not only produced early stability for osteoporotic distal radius fractures, but also avoided extensor tendon complications due to dorsal screw protrusion.
authors: Department of Anatomy, Southern Medical University, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong, P.R. China; Department of Orthopaedics, Shilongboai Hospital (The Eight People's Hospital of Dongguan), Dongguan, Guangdong, P.R. China.
authors: Xiong
authors: X
authors: Liu
authors: Department of Anatomy, Southern Medical University, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong, P.R. China; Department of Orthopaedics, Wuzhou Red Cross Hospital, Wuzhou, Guangxi, P.R. China.
authors: Wei-dong
authors: WD
authors: Wu
authors: Department of Anatomy, Southern Medical University, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong, P.R. China.
authors: Ya-feng
authors: YF
authors: Fang
authors: Department of Anatomy, Southern Medical University, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong, P.R. China.
authors: Mei-chao
authors: MC
authors: Zhang
authors: Department of Anatomy, Southern Medical University, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong, P.R. China.
authors: Wen-hua
authors: WH
authors: Huang
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D006801:Humans; D010024:Osteoporosis / Q000150:complications / Q000503:physiopathology*; D011885:Radius Fractures / Q000150:complications / Q000503:physiopathology / Q000601:surgery*