title: Biomechanical analysis of four types of internal fixation in subtrochanteric fracture models.
abstract: OBJECTIVE
  To compare the biomechanical properties of four types of internal fixation (proximal femoral nail [PFN], dynamic hip screw [DHS], dynamic condylar screw [DCS], and proximal femoral locking plate [PFLP]) for different types of subtrochanteric fractures.
  
  
  METHODS
  Thirty-two antiseptic femurs were randomly divided into four groups. After internal fixation had been implanted, different types of subtrochanteric fracture models were produced and each tested under vertical, torsional and vertical damage loads.
  
  
  RESULTS
  The stiffness ratio of PFN in each fracture model and failure load were the highest in the four groups; however, the torsional stiffness ratio was the lowest. Tension strain ratios of DHS and DCS on the lateral side became compression strain ratios with restoration of the medial fragment. The stiffness ratio of DHS was lower than PFLP in each fracture model, torsional stiffness ratio was the highest in fracture models II to V and the failure load was lower only than PFN. The stiffness ratio and failure load of DCS were both the lowest, torsional stiffness ratio was similar to PFLP's in fracture models II to V. The stiffness ratio of PFLP was only lower than PFN's in each fracture model, but the failure load was lower than DHS's.
  
  
  CONCLUSIONS
  Four types of internal fixation achieve better stabilities for type I subtrochanteric fractures. PFN and PFLP produce reliable stability in type IIIA subtrochanteric fractures. If the medial buttress is restored, DCS can be considered. For type IV subtrochanteric fractures, only PFN provides stable fixation. PFLP is suitable for comminuted fractures with large fragments.
authors.affiliation: Biomechanics Laboratory of Orthopaedics Institute, Tianjin Hospital, Tianjin, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Xin-long
authors.initials: XL
authors.lastname: Ma
authors.forename: Jian-xiong
authors.initials: JX
authors.lastname: Ma
authors.forename: Dan
authors.initials: D
authors.lastname: Xing
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Shao-wen
authors.initials: SW
authors.lastname: Zhu
authors.forename: Bao-yi
authors.initials: BY
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.forename: Rui
authors.initials: R
authors.lastname: Feng
authors.forename: Hao-bo
authors.initials: HB
authors.lastname: Jia
authors.forename: Jing-tao
authors.initials: JT
authors.lastname: Yu
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001860:Bone Plates; D001863:Bone Screws; D004868:Equipment Failure; D019544:Equipment Failure Analysis / Q000379:methods; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D006620:Hip Fractures / Q000601:surgery*; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D013314:Stress, Mechanical; D016474:Weight-Bearing
keywords: Biomechanics; Internal fixation; Strain distribution; Subtrochanteric fracture