title: Will My Tibial Fracture Heal? Predicting Nonunion at the Time of Definitive Fixation Based on Commonly Available Variables.
abstract: BACKGROUND
  Accurate prediction of tibial nonunions has eluded researchers. Reliably predicting tibial nonunions at the time of fixation could change management strategies and stimulate further research.
  
  
  OBJECTIVE
  We asked (1) whether data from medical records, fracture characteristics, and radiographs obtained at the time of fixation would identify features predictive of tibial fracture nonunion; and (2) whether this information could be used to create a model to assess the chance of nonunion at the time of intramedullary (IM) nail fixation of the tibia.
  
  
  METHODS
  We retrospectively reviewed all tibial shaft fractures treated at our center from 2007 to 2014. We conducted a literature review and collected data on 35 factors theorized to contribute to delayed bone healing. Patients were followed to fracture healing or surgery for nonunion. Patients with planned prophylactic nonunion surgery were excluded because their nonunions were anticipated and our focus was on unanticipated nonunions. Our cohort consisted of 382 patients treated with IM nails for tibial shaft fractures (nonunion, 56; healed, 326). Bivariate and multivariate regression techniques and stepwise modeling approaches examined the relationship between variables available at definitive fixation. Factors were included in our model if they were identified as having a modest to large effect size (odds ratio > 2) at the p < 0.05 level.
  
  
  RESULTS
  A multiple variable logistic regression model was developed, including seven factors (p < 0.05; odds ratio > 2.0). With these factors, we created the Nonunion Risk Determination (NURD) score. The NURD score assigns 5 points for flaps, 4 points for compartment syndrome, 3 points for chronic condition(s), 2 points for open fractures, 1 point for male gender, and 1 point per grade of American Society of Anesthesiologists Physical Status and percent cortical contact. One point each is subtracted for spiral fractures and for low-energy injuries, which were found to be predictive of union. A NURD score of 0 to 5 had a 2% chance of nonunion; 6 to 8, 22%; 9 to 11, 42%; and > 12, 61%.
  
  
  CONCLUSIONS
  The proposed nonunion prediction model (NURDS) seems to have potential to allow clinicians to better determine which patients have a higher risk of nonunion. Future work should be directed at prospectively validating and enhancing this model.
  
  
  METHODS
  Level III, diagnostic study.
authors.affiliation: Regions Hospital/University of Minnesota, St Paul, MN, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: O'Halloran
authors.affiliation: R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 2200 South Greene Street, SuiteT3R62, Baltimore, MD, 21201, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Coale
authors.affiliation: R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 2200 South Greene Street, SuiteT3R62, Baltimore, MD, 21201, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Costales
authors.affiliation: R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 2200 South Greene Street, SuiteT3R62, Baltimore, MD, 21201, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Zerhusen
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Renan C
authors.initials: RC
authors.lastname: Castillo
authors.affiliation: R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 2200 South Greene Street, SuiteT3R62, Baltimore, MD, 21201, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Nascone
authors.affiliation: R Adams Cowley Shock Trauma Center, Department of Orthopaedics, University of Maryland School of Medicine, 2200 South Greene Street, SuiteT3R62, Baltimore, MD, 21201, USA. rvo3@yahoo.com.
authors.forename: Robert V
authors.initials: RV
authors.lastname: O'Toole
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015142:Baltimore; D001858:Bone Nails; D016009:Chi-Square Distribution; D016208:Databases, Factual; D003661:Decision Support Techniques; D005260:Female; D005594:Fracture Fixation, Intramedullary / Q000009:adverse effects* / Q000295:instrumentation; D017102:Fracture Healing; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult