title: Assessment of implant position after total knee arthroplasty by dual-energy computed tomography.
abstract: BACKGROUND
  Correct alignment of prosthetic components is the most important factor for the success of total knee arthroplasty (TKA). Dual-energy computed tomography (DECT) may be a reliable method in determining implant position after TKA.
  
  
  OBJECTIVE
  To evaluate the accuracy and reproducibility of DECT in determining implant position after TKA.
  
  
  METHODS
  Institutional review board approval was obtained. Forty-five patients (age 75.2 ± 6.4 years) prospectively underwent TKA at our institution between May and December 2012. DECT was performed 1 year after surgery, using an alignment similar to a standing position and generating images at an extrapolated energy of 120 kVp, in order to reduce metal artifacts. Implant position was evaluated by two independent readers. Intra- and inter-observer agreements were calculated. DECT measurements on implant position were compared with the preoperative planning based on radiographs. Additional clinical and DECT findings were taken into account.
  
  
  RESULTS
  Metal artifact reduction was judged satisfactory in all cases. Regarding implant position assessed with DECT, good to excellent intra-observer (k: 0.74-0.87 and k: 0.75-0.88, respectively), and inter-observer agreement (k: 0.72-0.82) were found. In the comparison with preoperative planning, the widest limits of agreement were within 3.9° for the sagittal orientation of tibial component. A single patient with postoperative knee pain and stiffness had periprosthetic osteopenia, quadriceps femoris tendon calcifications, articular effusion, and excessive intrarotation of the femoral component.
  
  
  CONCLUSIONS
  DECT is an accurate and reproducible tool for determining implant position after TKA.
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy ferdinandoferrara1@gmail.com.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Ferrara
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cipriani
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Santi
authors.initials: S
authors.lastname: Rapisarda
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Iacobucci
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Magarelli
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Leone
authors.affiliation: Department of Radiological Sciences, Catholic University of the Sacred Heart, "A. Gemelli" Hospital, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Bonomo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D016477:Artifacts; D005260:Female; D006801:Humans; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000601:surgery*; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
keywords: Knee arthroplasty; dual-energy computed tomography; implant position control