title: Navicular subluxation as a radiographic finding in Charcot neuroarthropathy.
abstract: BACKGROUND
  Treatment of patients with Charcot midfoot destruction is a difficult and increasingly common clinical problem. The pathoanatomical features of Charcot neuropathy have been evaluated in only a few studies. This study evaluated whether medial navicular subluxation (adduction of the navicular on the talus) is a radiographic finding present in patients with Charcot neuroarthropathy.
  
  
  METHODS
  A retrospective review of 143 consecutive patients diagnosed with Charcot arthropathy of the foot from January 2004 to May 2011 was performed. Patients were identified based on a clinical diagnosis code 713.5 during an outpatient clinic visit with 2 surgeons at a single institution. After exclusion criteria were applied, a series of radiographs of 50 feet in 40 patients were compared with radiographs from an age-matched control group. Radiographic data including talonavicular coverage angle and talonavicular uncoverage percentage were collected.
  
  
  RESULTS
  The mean talonavicular coverage angle of the Charcot arthropathy group was 1.5 degrees and of the control group 12.1 degrees (P < .05). The talonavicular uncoverage value for the Charcot arthropathy group was 12.2% and for the control group 22.0% (P < .001).
  
  
  CONCLUSIONS
  Medial navicular subluxation was a radiographic finding that was more commonly present in patients with Charcot arthropathy than in a matched control group. It is theorized that this finding is attributable to an unopposed pull of the posterior tibial tendon on the destabilized navicular.
  
  
  METHODS
  Level IV, retrospective case series.
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, CA, USA.
authors.forename: Allyson
authors.initials: A
authors.lastname: Estess
authors.forename: Nicole
authors.initials: N
authors.lastname: Marquand
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Charlton
authors.forename: David B
authors.initials: DB
authors.lastname: Thordarson
mesh_terms: D000328:Adult; D000368:Aged; D001177:Arthropathy, Neurogenic / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013639:Tarsal Bones / Q000000981:diagnostic imaging*; D013640:Tarsal Joints / Q000000981:diagnostic imaging*
keywords: Charcot; arthropathy; coverage; diabetes; talonavicular