title: Does the PFNA™ nail limit impaction in unstable intertrochanteric femoral fracture? A 115 case-control series.
abstract: BACKGROUND
  Femoral neck shortening after dynamic fixation of extra-capsular fracture may impair functional results, but is rarely assessed. The present study measured impaction in stable and unstable fractures (on the Ender classification) treated by PFNA™ nail. The objectives were: 1) to validate the Ender classification to assess fracture stability; 2) to determine whether neck shortening and head purchase quality varied with stability; and 3) to determine the functional impact of femoral neck shortening.
  
  
  OBJECTIVE
  The study hypothesis was that the PFNA™ nail stabilizes unstable as well as stable fractures.
  
  
  METHODS
  One hundred and fifteen consecutive patients, aged over 70 years, operated on for intertrochanteric fracture using the PFNA™ nail were followed up prospectively for 6 months. Multivariate analysis, including age, gender, assembly quality and body-mass index, was applied to assess the predictive power of the Ender classification with respect to femoral neck shortening. Secondly, patients were grouped according to stable versus unstable fracture (n=70 and 45, respectively), and impaction and femoral head purchase were assessed on a dedicated radiographic protocol. Functional results were assessed on Parker score.
  
  
  RESULTS
  In the unstable fracture group, 3 assembly failures required revision by total hip replacement. Ender grade>2 was significantly predictive of>5mm neck shortening. Neck shortening was greater in unstable fracture: 8.1 ± 8.4mm (range, 4-32 mm), versus 2.5 ± 3.7 mm (range, 3-14 mm) (P=0.0004). Mean blade cut-through was 1.2 ± 2.9 mm (range, 1-12 mm) in unstable fracture, versus 0.3 ± 1.3 mm (range, 1-6mm) (P=0.02). Mean cut-out was 2.3 ± 6 mm (range, 2-21 mm) in unstable fracture, versus 0.5 ± 2.6 mm (range, 1-8mm) (P=0.03). Parker scores diminished comparably in the two groups, without significant difference at follow-up: 3.9 ± 2.6 (range, 0-9) in stable and 3.1 ± 1.9 (range, 0-8) in unstable fracture; reduction in Parker score showed no correlation with femoral neck shortening (r=0.013, P=0.88).
  
  
  CONCLUSIONS
  The PFNA™ nail provides poorer stabilization of unstable compared to stable fracture. Femoral neck shortening should be taken into account in assessing internal fixation hardware perfomances.
  
  
  METHODS
  Level III. Prospective case-control study.
authors.affiliation: Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Hélin
authors.affiliation: Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Pelissier
authors.affiliation: Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Boyer
authors.affiliation: Département de biostatistiques, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France.
authors.forename: T
authors.initials: T
authors.lastname: Delory
authors.affiliation: Département de biostatistiques, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France.
authors.forename: C
authors.initials: C
authors.lastname: Estellat
authors.affiliation: Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France. Electronic address: philippe.massin@bch.aphp.fr.
authors.forename: P
authors.initials: P
authors.lastname: Massin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data; D001858:Bone Nails; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D011446:Prospective Studies; D011859:Radiography
keywords: Fixation failure; Internal fixation; Intertrochanteric fracture; O.R.I.F unstable fracture; Secondary displacement