title: Congruity of the subtalar joint in tongue fracture of the calcaneus: an anatomical study.
abstract: METHODS
  An anatomic study.
  
  
  OBJECTIVE
  To evaluate the effect of displacement of the fractured posterior facet in tongue fracture of the calcaneus on the congruity of the subtalar joint.
  
  
  METHODS
  Eleven feet were used in this study. Seven females and four males with age range from 59 to 78. The specimens were dissected from both the lateral and the medial aspects of the calcaneus to expose these surfaces. A primary fracture line was created first, then a secondary line was engineered to simulate tongue fracture. Displacement of the superio-lateral fragment was done with 5-mm increment. Radiography was performed and the graphs were scanned and studied on specific computer software to explore the effects of displacement on joint congruity.
  
  
  RESULTS
  The anterior end of the fragment of the tongue fracture, when displaced, not only is depressed but also rotated in the sagittal plane in a downward or planterward direction. The articular surface of the posterior facet of the calcaneus and the inferior facet of the talus are maintained in congruence with each other despite the varying degree of displacement and rotation.
  
  
  CONCLUSIONS
  Congruity of the subtalar joint in tongue fractures is maintained despite different degrees of displacement. This study explains why the non-surgical treatment outcome is comparable to that of the operative treatment in tongue fractures of calcaneus. It also explains why tongue fractures have a good outcome with closed reduction.
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Ohio, Toledo 43614, USA.
authors.forename: N A
authors.initials: NA
authors.lastname: Ebraheim
authors.forename: F F
authors.initials: FF
authors.lastname: Sabry
authors.forename: S
authors.initials: S
authors.lastname: Haman
authors.forename: H
authors.initials: H
authors.lastname: Elgafy
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D002111:Calcaneus / Q000033:anatomy & histology / Q000293:injuries*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular; D012680:Sensitivity and Specificity; D013380:Subtalar Joint / Q000473:pathology / Q000503:physiopathology*