title: Tip apex distance, hip screw placement, and neck shaft angle as potential risk factors for cut-out failure of hip screws after surgical treatment of intertrochanteric fractures.
abstract: OBJECTIVE
  To describe the quality of osteosynthesis after intertrochanteric fractures evaluation of tip apex distance (TAD) and position of the hip screw have been established. Furthermore, a slightly valgus fracture reduction has been suggested to reduce the risk of cut-out failure. However, uniform recommendations for optimal screw positioning and fracture reduction are still missing. The purpose of our study was to confirm potential risk factors for cut-out of hip screws of intertrochanteric fractures and to provide recommendations for practical clinical use.
  
  
  METHODS
  A retrospective analysis of all patients with intertrochanteric fractures treated with a DHS or a gamma nail between January of 2007 and May of 2010 was performed at a level I trauma center.
  
  
  RESULTS
  Two hundred thirty-five patients with intertrochanteric fractures after intra- and extramedullary stabilization were analyzed. A TAD of more than 25 mm was demonstrated to be the most important factor for cut-out in stable and unstable fractures. Fracture reduction with a valgus NSA of 5-10° was associated with a trend towards a lower rate of screw cut-out while an anterior placement of the screw (Parker's ratio index of <40) significantly increased cut-out incidence.
  
  
  CONCLUSIONS
  According to our results, the TAD should not exceed 25 mm in stable (AO/OTA A1) as well as unstable (AO/OTA A2) fractures. An increased anterior hip screw placement should be avoided while fracture reduction with a slight valgus Neck Shaft seems favorable.
authors.affiliation: Trauma Department, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. andruszkow.hagen@mh-hannover.de
authors.forename: Hagen
authors.initials: H
authors.lastname: Andruszkow
authors.forename: Michael
authors.initials: M
authors.lastname: Frink
authors.forename: Cornelia
authors.initials: C
authors.lastname: Frömke
authors.forename: Amir
authors.initials: A
authors.lastname: Matityahu
authors.forename: Christian
authors.initials: C
authors.lastname: Zeckey
authors.forename: Philipp
authors.initials: P
authors.lastname: Mommsen
authors.forename: Stefanie
authors.initials: S
authors.lastname: Suntardjo
authors.forename: Christian
authors.initials: C
authors.lastname: Krettek
authors.forename: Frank
authors.initials: F
authors.lastname: Hildebrand
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws / Q000009:adverse effects*; D005260:Female; D005272:Femur Neck / Q000473:pathology; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D006620:Hip Fractures / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D016268:Internal Fixators; D008297:Male; D011475:Prosthesis Failure / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D014193:Trauma Centers