title: An anatomic study of coronoid cartilage thickness with special reference to fractures.
abstract: BACKGROUND
  Current coronoid fracture classification systems are based on fragment size and configuration using plain radiographs and/or computed tomography (CT). During surgery, coronoid fracture fragments appear much larger than anticipated because cartilage is radiolucent and therefore not accounted for with preoperative imaging. The purpose of this imaging study was to quantify the articular cartilage thickness of the coronoid, with reference to coronoid fractures.
  
  
  METHODS
  Twenty-four cadaveric ulnae were dissected, imaged with CT, and analyzed by use of image analysis software. Thirteen identifiable landmarks were chosen on the coronoid, olecranon, and proximal radioulnar joint to measure articular cartilage thickness. Intraobserver reliability and interobserver reliability were determined.
  
  
  RESULTS
  Cartilage thickness was highest at the coronoid tip, with a mean of 3.0 mm (range, 1.7-4.6 mm). Cartilage thickness at the tip correlated inversely with age (P < .01) and correlated strongly with overall ulnar height and ulnar length (P < .05). All measurements had excellent intraobserver and interobserver reliability.
  
  
  CONCLUSIONS
  The thickness of cartilage on the coronoid tip is not inconsequential. The results of this study indicate that a 2-mm coronoid tip fracture on CT scan may actually appear to be a mean of 5 mm thick when viewed at the time of surgery. Clinically, this is important because it may alter the classification, the decision to treat, or the type of fixation used. Importantly, biomechanical cadaveric studies assessing coronoid injuries have incorporated cartilage thickness into coronoid size measurements when creating simulated fractures; therefore, it is critical that the conclusions of such biomechanical studies be scrutinized with regard to their clinical recommendations. Surgeons should be aware of these discrepancies.
authors: Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada.
authors: Samah
authors: S
authors: Rafehi
authors: Emily
authors: E
authors: Lalone
authors: Marjorie
authors: M
authors: Johnson
authors: Graham J W
authors: GJ
authors: King
authors: George S
authors: GS
authors: Athwal
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D004551:Elbow Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D014457:Ulna / Q000033:anatomy & histology* / Q000601:surgery; D014458:Ulna Fractures / Q000000981:diagnostic imaging / Q000601:surgery; D000092464:Elbow Injuries