title: Central head perforation, or "cut through," caused by the helical blade of the proximal femoral nail antirotation.
abstract: OBJECTIVE
  This study was designed to investigate the specific type and incidence of implant failure in patients with a proximal femur fracture treated with a proximal femoral nail antirotation. This device has a helical-shaped blade as a neck-head holding device, instead of the lag screw used in other intramedullary nails. The advantage of the blade is believed to originate from bone impaction and a larger bone-implant interface in comparison with the lag screw design, with consequential greater mechanical resistance to torsion in the cancellous bone.
  
  
  METHODS
  This is a retrospective cohort study conducted at the state hospital of Winterthur, Switzerland. From December 2006 until November 2008, 210 consecutive patients were treated with a pertrochanteric femur fracture (OTA type 31-A1, 31-A2, and 31-A3) using a proximal femoral nail antirotation. One hundred and twelve patients were followed up clinically for a minimum of 12 months after discharge. Clinical and radiologic assessment of fracture healing and/or implant failure was investigated.
  
  
  RESULTS
  We report 7 cases of implant failure with a "Cut Through," defined as a postoperative central perforation of the spiral blade into the hip joint, without any displacement of the neck-head fragment.
  
  
  CONCLUSIONS
  Cut through needs to be distinguished from the well-known anterocranial perforation combined with a varus displacement of the neck-head fragment, known as "Cut Out," seen with intramedullary nails utilizing lag screws.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Surgery, Kantonsspital Winterthur, Winterthur, Switzerland. hans-curd.frei@ksw.ch
authors.forename: Hans-Curd
authors.initials: HC
authors.lastname: Frei
authors.forename: Thomas
authors.initials: T
authors.lastname: Hotz
authors.forename: Dieter
authors.initials: D
authors.lastname: Cadosch
authors.forename: Mark
authors.initials: M
authors.lastname: Rudin
authors.forename: Kurt
authors.initials: K
authors.lastname: Käch
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001858:Bone Nails / Q000706:statistics & numerical data*; D001863:Bone Screws / Q000706:statistics & numerical data*; D015331:Cohort Studies; D015897:Comorbidity; D005264:Femoral Fractures / Q000453:epidemiology* / Q000601:surgery*; D025981:Hip Injuries / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012306:Risk; D013557:Switzerland / Q000453:epidemiology; D016896:Treatment Outcome; D014950:Wounds, Penetrating / Q000453:epidemiology*