title: How to prevent cut-out and cut-through in biaxial proximal femoral nails: is there anything beyond lag screw positioning and tip-apex distance?
abstract: OBJECTIVE
  Hip perforation is a major complication in proximal femoral nailing. For biaxial nails, knowledge of their biomechanics is limited. Besides re-evaluation of accepted risk factors like the tip-apex distance (TAD), we analysed the influence of anti-rotational pin length.
  
  
  METHODS
  We compared 22 hip perforation cases to 50 randomly chosen controls. TAD, lag-screw position, angle between lag-screw and femoral neck axis, lag-screw gliding capacity, displacement and anti-rotational pin length were investigated.
  
  
  RESULTS
  Hip perforation was associated with a higher angle of deviation between lag-screw and femoral neck axis (p = 0.001), a lower telescoping capacity of the lag screw (p = 0.02), and higher TAD (p = 0.048). If the anti-rotational pin exceeded a line connecting the tip of the nail and the lag screw (NS line), hip perforation incidence was increased (p = 0.009). Inadequate pin length resulted in an odds ratio of 10.8 for hip perforation (p = 0.001).
  
  
  CONCLUSIONS
  In biaxial nails anti-rotational element positioning is underestimated, however, crucial.
authors: Department of Trauma and Orthopaedic Surgery, Klinikum Nuernberg, Breslauer Str. 201, 90471 Nuernberg, Germany. birgit.zirngibl@klinikum-nuernberg.de
authors: Birgit
authors: B
authors: Zirngibl
authors: Roland
authors: R
authors: Biber
authors: Hermann Josef
authors: HJ
authors: Bail
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D001858:Bone Nails / Q000009:adverse effects* / Q000145:classification; D001863:Bone Screws / Q000009:adverse effects* / Q000145:classification; D016022:Case-Control Studies; D005264:Femoral Fractures / Q000145:classification / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D025981:Hip Injuries / Q000453:epidemiology / Q000517:prevention & control*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D016896:Treatment Outcome
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