title: Morphomic measurement of the temporalis muscle and zygomatic bone as novel predictors of hospital-based clinical outcomes in patients with mandible fracture.
abstract: BACKGROUND
  Patients with mandibular fracture often have comorbidities and concomitant injuries making the decision for when and how to operate a challenge. Physicians describe "temporalis wasting" as a finding that indicates frailty; however, this is a subjective finding without quantitative values. In this study, we demonstrate that decreased morphomic values of the temporalis muscle and zygomatic bone are an objective measure of frailty associated with increased injury-induced morbidity as well as negative impact on overall hospital-based clinical outcomes in patients with mandible fracture.
  
  
  METHODS
  Computed tomographic (CT) scans from all patients with a diagnosis of a mandible fracture in the University of Michigan trauma registry and with a hospital admission were collected from the years 2004 to 2011. Automated, high-throughput CT analysis was used to reconstruct the anatomy and quantify morphomic values (temporalis volume, area and thickness, and zygomatic thickness) in these patients using MATLAB v13.0 (MathWorks Inc, Natick, MA, USA). Subsequently, a subset of 16 individuals with a Glasgow Coma Scale of 14 or 15 was analyzed to control for brain injury. Clinical data were obtained, and the association between morphomic measurements and clinical outcomes was evaluated using Pearson correlation for unadjusted analysis and multiple regression for adjusted analysis.
  
  
  RESULTS
  The mean age of patients in the study was 47.1 years. Unadjusted analysis using Pearson correlation revealed that decreases in zygomatic bone thickness correlated strongly with increases in hospital, intensive care unit, and ventilator days (P < 0.0001, P = 0.0003, and P = 0.0017, respectively). Furthermore, we found that decreases in temporalis mean thickness correlated with increases in hospital and ventilator days (P = 0.0264 and P = 0.0306, respectively). Similarly, decreases in temporalis local mean thickness are significantly correlated with increases in hospital and ventilator days (P = 0.0232 and P = 0.0472, respectively).
  
  
  CONCLUSIONS
  Decreased thicknesses of the zygomatic bone and temporalis muscle are significantly correlated with higher hospital, ventilator, and intensive care unit days in patients with mandibular fracture receiving reconstructive operations. This morphomic methodology provides an accurate, quantitative means to evaluate craniofacial trauma patient frailty, injury, and outcomes using routinely obtained CT scans. In the future, we plan to apply this approach to determine preoperative risk stratification and assist in surgical planning.
authors.affiliation: From the *Section of Plastic Surgery, Department of Surgery, and †Department of Biostatistics, University of Michigan, Ann Arbor, MI; and ‡International Center for Automotive Medicine, University of Michigan, Ann Arbor, MI.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lisiecki
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.forename: Jacob
authors.initials: J
authors.lastname: Rinkinen
authors.forename: Sara
authors.initials: S
authors.lastname: De La Rosa
authors.forename: Binu
authors.initials: B
authors.lastname: Enchakalody
authors.forename: Robert Cameron
authors.initials: RC
authors.lastname: Brownley
authors.forename: Stewart C
authors.initials: SC
authors.lastname: Wang
authors.forename: Steven R
authors.initials: SR
authors.lastname: Buchman
authors.forename: Benjamin
authors.initials: B
authors.lastname: Levi
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D002508:Cephalometry / Q000379:methods*; D015897:Comorbidity; D005260:Female; D017102:Fracture Healing / Q000502:physiology*; D015600:Glasgow Coma Scale; D006305:Health Status Indicators; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery; D008337:Mandibular Fractures / Q000000981:diagnostic imaging* / Q000601:surgery*; D008875:Middle Aged; D010347:Patient Care Planning; D011379:Prognosis; D019651:Plastic Surgery Procedures; D013703:Temporal Muscle / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D015050:Zygoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*