title: Femoral neck fracture osteosynthesis by the biplane double-supported screw fixation method (BDSF) reduces the risk of fixation failure: clinical outcomes in 207 patients.
abstract: BACKGROUND
  Osteosynthesis of femoral neck fractures is related up to 46% rate of complications. The novel method of biplane double-supported screw fixation (BDSF; Filipov's method) offers better stability using three medially diverging cannulated screws with two of them buttressed on the calcar. Biomechanically, the most effective component is the distal screw placed at steeper angle and supported on a large area along the distal and posterior cortex of the femoral neck following its spiral anterior curve. Thereby, BDSF achieves the strongest possible distal-posterior cortical support for the fixation construct, which allows for immediate full weight-bearing. The aim of this study was to evaluate the outcomes from the first 5-year period of BDSF clinical application.
  
  
  METHODS
  Subject of this retrospective study were 207 patients with displaced Garden III-IV femoral neck fractures treated with BDSF. Three 7.3-mm cannulated screws were laid in two medially diverging oblique planes. The distal and the middle screws were supported on the calcar. The distal screw had additional support on the posterior neck cortex.
  
  
  RESULTS
  The outcomes in 207 patients were analysed in 29.6 ± 16.8 months follow-up. Bone union occurred in 96.6% of the cases (males 97.6%, females 96.4%, P = 0.99). Rate of nonunion was 3.4%, including fixation failure (2.4%), pseudoarthrosis (0.5%) and nonunion with AVN (0.5%). Rate of AVN was 12.1% (males 4.8%, females 13.9%, P = 0.12). Modified Harris hip score was 86.2 ± 18.9 (range 10-100), with no significant difference between genders, P = 0.07. Older patients were admitted with significantly more comorbidities (P = 0.001), and on follow-up they were significantly less mobile (P = 0.005) and had significantly more difficulties to put socks and shoes on (P < 0.001).
  
  
  CONCLUSIONS
  By providing additional cortical support, the novel BDSF method enhances femoral neck fracture fixation strength.
authors.affiliation: Vitosha Hospital, Simeonovsko shose str.108-B, 1700, Sofia, Bulgaria. vitosha_hospital@abv.bg.
authors.forename: Orlin
authors.initials: O
authors.lastname: Filipov
authors.affiliation: Cantonal Hospital Baselland, University Basel, Basel, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Stoffel
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.affiliation: Cantonal Hospital Graubuenden, Chur, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Sommer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D001863:Bone Screws; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure
keywords: BDSF; Biplane; Femoral neck fracture; Fixation; Hip fractures; Osteosynthesis