title: Anterior locking plate reduces trochanteric fracture migrations during hip extension.
abstract: BACKGROUND
  Greater trochanter fractures or osteotomies fixed with lateral plates still present high rates of complications. Unblocked greater trochanter anterior movement during hip extension might be a possible cause of failure. This study aimed to determine, under stair climbing conditions, the biomechanical behaviour of a greater trochanter fragment and the impact of an anterior locking plate on its migration.
  
  
  METHODS
  Eighteen femurs paired from nine fresh frozen cadaveric specimens were tested on a quasi-dynamic stair climbing cycling test bench. Left and right sides with greater trochanter fractures were randomly fixed either with an antero-lateral locking plate or with a lateral locking plate. Migrations, defined as the remaining movements of the unloaded greater trochanter fragment, were measured for all 18 femurs.
  
  
  RESULTS
  During hip extension, multi-directional greater trochanter fragment movements occurred and showed a back-and-forth anterior rotation. The lateral locking plate failed due to greater trochanter fragment rotation around the superior axis and anterior translation. The antero-lateral locking plate significantly reduced greater trochanter anterior migration (-0.9 mm ± 1.6) compared to the lateral locking plate (9.6 mm ± 9.5).
  
  
  CONCLUSIONS
  Hip extension provides a plausible explanation for the high rate of post-operative failures of greater trochanter fixations. An antero-lateral locking plate represents an efficient surgical alternative counteracting the multi-directional greater trochanter movements occurring during hip extension.
authors.affiliation: Mechanical Engineering Department, École de technologie supérieure, Montreal, Quebec, Canada; Laboratoire d'imagerie et d'orthopédie, Hôpital du Sacré-Cœur, Research Center, Montreal, Quebec, Canada.
authors.forename: Luc P
authors.initials: LP
authors.lastname: Cloutier
authors.affiliation: Laboratoire d'imagerie et d'orthopédie, Hôpital du Sacré-Cœur, Research Center, Montreal, Quebec, Canada.
authors.forename: G Yves
authors.initials: GY
authors.lastname: Laflamme
authors.affiliation: Laboratoire d'imagerie et d'orthopédie, Hôpital du Sacré-Cœur, Research Center, Montreal, Quebec, Canada.
authors.forename: Jeremie
authors.initials: J
authors.lastname: Menard
authors.affiliation: Mechanical Engineering Department, École de technologie supérieure, Montreal, Quebec, Canada; Laboratoire d'imagerie et d'orthopédie, Hôpital du Sacré-Cœur, Research Center, Montreal, Quebec, Canada. Electronic address: yvan.petit@etsmtl.ca.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Petit
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D001842:Bone and Bones / Q000502:physiology; D002102:Cadaver; D004867:Equipment Design; D005260:Female; D005269:Femur / Q000502:physiology*; D006620:Hip Fractures / Q000601:surgery*; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D009985:Orthopedics / Q000379:methods; D011474:Prosthesis Design; D012086:Reoperation; D012399:Rotation
keywords: Anterior locking plate; Greater trochanter; Hip revision surgery; Multi-directional migration; Quasi-dynamic stair climbing