title: Predictive factors of distal femoral fracture nonunion after lateral locked plating: a retrospective multicenter case-control study of 283 fractures.
abstract: BACKGROUND
  Reported initial success rates after lateral locked plating (LLP) of distal femur fractures have led to more concerning outcomes with reported nonunion rates now ranging from 0 to 21%. Reported factors associated with nonunion include comorbidities such as obesity, age and diabetes. In this study, our goal was to identify patient comorbidities, injury and construct characteristics that are independent predictors of nonunion risk in LLP of distal femur fractures; and to develop a predictive algorithm of nonunion risk, irrespective of institutional criteria for clinical intervention variability.
  
  
  METHODS
  A retrospective review of 283 distal femoral fractures in 278 consecutive patients treated with LLP at three Level1 academic trauma centers. Nonunion was liberally defined as need for secondary procedure to manage poor healing based on unrestricted surgeon criteria. Patient demographics (age, gender), comorbidities (obesity, smoking, diabetes, chronic steroid use, dialysis), injury characteristics (AO type, periprosthetic fracture, open fracture, infection), and management factors (institution, reason for intervention, time to intervention, plate length, screw density, and plate material) were obtained for all participants. Multivariable analysis was performed using logistic regression to control for confounding in order to identify independent risk factors for nonunion.
  
  
  RESULTS
  28 of the 283 fractures were treated for nonunion, 13 were referred to us from other institutions. Obesity (BMI>30), open fracture, occurrence of infection, and use of stainless steel plate were significant independent risk factors (P<0.01). A predictive algorithm demonstrates that when none of these variables are present (titanium instead of stainless steel) the risk of nonunion requiring intervention is 4%, but increases to 96% with all factors present. When a stainless plate is used, obesity alone carries a risk of 44% while infection alone a risk of 66%. While Chi-square testing suggested no institutional differences in nonunion rates, the time to intervention for nonunion varied inversely with nonunion rates between institutions, indicating varying trends in management approach.
  
  
  CONCLUSIONS
  Obesity, open fracture, occurrence of infection, and the use of stainless steel are prognostic risk factors of nonunion in distal femoral fractures treated with LLP independent of differing trends in how surgeons intervene in the management of nonunion.
authors.affiliation: Beth Israel Deaconess Medical Center, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA. Electronic address: ekrodrig@bidmc.harvard.edu.
authors.forename: Edward K
authors.initials: EK
authors.lastname: Rodriguez
authors.affiliation: University of Maryland, Shock Trauma, Department of Orthopaedics, Baltimore, MD, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Boulton
authors.affiliation: Brigham and Women's Hospital, Department of Orthopedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Weaver
authors.affiliation: Beth Israel Deaconess Medical Center, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Herder
authors.affiliation: Brigham and Women's Hospital, Department of Orthopedic Surgery, Harvard Medical School, Boston, MA, USA; Massachusetts General Hospital, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Jordan H
authors.initials: JH
authors.lastname: Morgan
authors.affiliation: Beth Israel Deaconess Medical Center, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Aron T
authors.initials: AT
authors.lastname: Chacko
authors.affiliation: Beth Israel Deaconess Medical Center, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Appleton
authors.affiliation: Boston Children's Hospital, Departments of Anesthesia and Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.affiliation: Brigham and Women's Hospital, Department of Orthopedic Surgery, Harvard Medical School, Boston, MA, USA; Massachusetts General Hospital, Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Vrahas
mesh_terms: D000369:Aged, 80 and over; D001860:Bone Plates / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D005264:Femoral Fractures / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods*; D017102:Fracture Healing; D005597:Fractures, Open / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D005599:Fractures, Ununited / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D011379:Prognosis; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D013530:Surgical Wound Infection / Q000150:complications / Q000517:prevention & control*; D016896:Treatment Outcome
keywords: Distal femur fracture; LISS; Locked plating; Nonunion; Periprosthetic; Supracondylar