title: Preoperative assessment of the cancellous bone mineral density of the proximal humerus using CT data.
abstract: BACKGROUND
  Osteoporotic fractures of the proximal humerus show an increasing incidence. Osteoporosis not only influences the fracture risk after low-energy trauma, but also affects the mechanical stability of internal fixation. Preoperative assessment of the local bone quality may be useful in the surgical treatment of patients sustaining these injuries. The aim of the present study was to present a method for the preoperative assessment of the local cancellous bone mineral density (BMD) of the proximal humerus using CT data.
  
  
  METHODS
  In the first part of the study, CT scans of 30 patients with unilateral fractures of the proximal humerus after low-energy trauma were used. The local BMD was assessed on the contralateral uninjured side. All 30 patients additionally underwent dual-emission X-ray absorptiometry (DXA) of the lumbar spine, proximal femur, and forearm of the side of the uninjured proximal humerus within 6 weeks after trauma. Three independent trauma surgeons performed measurements on the uninjured proximal humerus twice with a time interval of 4 weeks in order to assess the inter- and intraobserver reliability of the method. In the second part of the study, the local BMD of 507 patients with either proximal humerus fractures or chronic shoulder instability was assessed by a single trauma surgeon. In both parts, the average HU values in standardized ROIs of the humeral head were automatically calculated after correcting for HU values below the water equivalent. A linear calibration equation was computed for the calculation from HU to BMD using a calibration device (EFP).
  
  
  RESULTS
  The intra- and interobserver reliability was high (ICC > 0.95). Correlation coefficients between the local BMD of the proximal humerus and other anatomical sites were between 0.35 (lumbar spine) and 0.64 (forearm). We found a high correlation between the local BMD and age. The BMD in the fracture group was significantly lower than in the instability group. These patients were significantly older and more likely to be female.
  
  
  CONCLUSIONS
  Our method may provide a preoperative tool for the assessment of the local bone quality of the proximal humerus using CT data. Therapeutic adjustments such as augmentation or primary arthroplasty may be considered in patients with very low local BMD.
authors.affiliation: Department of Trauma Surgery and Sports Medicine, Innsbruck Medical University, Anichstraße 35, 6020, Innsbruck, Austria. Dietmar@krappinger.eu
authors.forename: Dietmar
authors.initials: D
authors.lastname: Krappinger
authors.forename: Tobias
authors.initials: T
authors.lastname: Roth
authors.forename: Martin
authors.initials: M
authors.lastname: Gschwentner
authors.forename: Armin
authors.initials: A
authors.lastname: Suckert
authors.forename: Michael
authors.initials: M
authors.lastname: Blauth
authors.forename: Clemens
authors.initials: C
authors.lastname: Hengg
authors.forename: Franz
authors.initials: F
authors.lastname: Kralinger
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D005260:Female; D006801:Humans; D008297:Male; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging*; D011300:Preoperative Care; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012784:Shoulder Fractures / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*