title: Femoral offset following trochanteric femoral fractures: a prospective observational study.
abstract: BACKGROUND
  Reconstruction of the femoral offset reportedly improves outcome following total hip arthroplasty, but little is known of its influence following hip fractures. We aimed to establish the effect of the femoral offset on the medium-term functional outcome in elderly patients who had sustained trochanteric fractures requiring proximal femoral nailing.
  
  
  METHODS
  We measured the rotation corrected femoral offset (FORC) and relative femoral offset (FORL) on plain anteroposterior radiographs of the hip in 188 patients (58 male, 130 female) with a trochanteric fracture who underwent proximal femoral nailing at our institution. The primary outcome measure was the Harris hip score (HSS) 6 and 12 months postoperatively; the Barthel index was assessed as a secondary outcome.
  
  
  RESULTS
  The mean FORC after surgery was 58 mm (±11 mm), while the mean FORL was 1.21 (±0.22). At final follow up, we found significant inverse relationships (Spearman's rank correlation coefficient, ρ) between FORC and FORL and the functional outcome assessed by the HSS (FORC: ρ = -0.207, p = 0.036; FORL: ρ = -0.247, p = 0.012), and FORL and the Barthel index (FORC: ρ = -147, p = 0.129; FORL: ρ = -0.192, p = 0.046). A consistent trend was observed after adjustment for confounding variables.
  
  
  CONCLUSIONS
  Our results underline the biomechanical importance of the femoral offset for medium-term outcomes in elderly patients with trochanteric fractures. In contrast with the published findings on total hip arthroplasty, we found an inverse correlation between functional outcome and the extent of the reconstructed femoral offset.
  
  
  METHODS
  Level I - Prognostic study.
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Buecking
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany; Department of Orthopaedic and Trauma Surgery, University Hospital of Cologne, Cologne, Germany.
authors.forename: Christoph Kolja
authors.initials: CK
authors.lastname: Boese
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Seifert
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Ruchholtz
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Frink
authors.affiliation: Center for Orthopaedics and Trauma Surgery, University of Giessen and Marburg, Marburg, Germany. Electronic address: lechler@med.uni-marburg.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lechler
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005594:Fracture Fixation, Intramedullary; D006620:Hip Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D011379:Prognosis; D011446:Prospective Studies; D016059:Range of Motion, Articular; D020127:Recovery of Function; D015203:Reproducibility of Results; D012399:Rotation; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: AP – anteroposterior; ASA – American society of anaesthesiologists; CCD – caput-collum-diaphyseal; FH – femoral head circumference; FO – femoral offset; FO(P) – projected femoral offset; FO(RC) – rotation-corrected femoral offset; HR – hip rotation; MMSE – mini–mental state examination; RCF – rotation-correction-factor as assessed; THA – total hip arthroplasty; by the tangent function; femoral offset; femoroacetabular impingement; hip biomechanics; hip fracture; proximal femoral nailing; γ(I) – gamma angle of the implant; γ(p) – projected gamma angle of the implant