title: Total ankle arthroplasty: optimizing computed tomography imaging protocol.
abstract: OBJECTIVE
  To evaluate parameters and positioning when imaging total ankle prostheses on computed tomography (CT).
  
  
  METHODS
  An ankle prosthesis implanted into a pig's knee joint underwent 16 different CT imaging protocols. Four defects were drilled around prosthesis components simulating periprosthetic osteolytic lesions. The specimen with the implant was imaged in four different orientations with the tibial stem parallel to the table and at 25, 45, and 90° angles to it. The protocol consisted of scanning at 100, 120, and 140 kVp in every position with a pitch of 1.2. The scanning at 120 kVp in every position was repeated with a pitch of 1.0.
  
  
  RESULTS
  CT proved to be a reliable imaging modality when studying periprosthetic lesions adjacent to the ankle prosthesis when the tibial stem alignment was parallel to the table. When imaging at higher angles, metal artifacts distorted the image, making the analysis of periprosthetic bone structure unreliable. There were no statistically significant differences between different tube voltages or pitch in volume measurements of the osteolytic lesions.
  
  
  CONCLUSIONS
  CT is a reliable imaging method to evaluate periprosthetic bone structure around ankle prostheses when orientation of the prosthesis and acquisition parameters is optimized.
authors.affiliation: Medical Imaging Centre of Southwest Finland, Turku University Hospital, Kiinamyllynkatu 4-8, 20520, Turku, Finland, ia.kohonen@tyks.fi.
authors.forename: Ia
authors.initials: Ia
authors.lastname: Kohonen
authors.forename: Helka
authors.initials: H
authors.lastname: Koivu
authors.forename: Tero
authors.initials: T
authors.lastname: Vahlberg
authors.forename: Heli
authors.initials: H
authors.lastname: Larjava
authors.forename: Kimmo
authors.initials: K
authors.lastname: Mattila
mesh_terms: D000818:Animals; D000843:Ankle Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D058737:Arthroplasty, Replacement, Ankle / Q000379:methods*; D016477:Artifacts; D006801:Humans; D066298:In Vitro Techniques; D056888:Patient Positioning / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
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