title: Single Versus Multiple-Radii Cruciate-Retaining Total Knee Arthroplasty: An In Vivo Mobile Fluoroscopy Study.
abstract: BACKGROUND
  Previous fluoroscopic studies, using static C-arm systems, have shown nonnormal kinematic patterns in cruciate-retaining (CR) total knee arthroplasty (TKA). This study compares in vivo the kinematic differences in subjects implanted with single sagittal radius (SR) vs multiradii (MR) CR TKA for various activities using a novel mobile fluoroscopic system.
  
  
  METHODS
  Using mobile fluoroscopy and 3D to 2D registration, tibiofemoral kinematics were analyzed for 25 subjects with an SR, symmetrical condylar CR TKA and 25 subjects with an MR, asymmetric condylar CR TKA for three dynamic weight-bearing activities: (1) deep knee bend (DKB), (2) walking up a ramp, and (3) walking down a ramp.
  
  
  RESULTS
  During DKB, from full extension to maximum knee flexion, the SR (-0.43 ± 3.43 mm) and MR (-1.00 ± 3.23 mm) groups experienced statistically similar anterior/posterior (AP) motion in the lateral condyle. The SR (3.51 ± 2.68 mm) group had significant anterior movement compared to the MR (-0.42 ± 2.20 mm) group in the medial condyle. This resulted in a significantly larger amount of normal axial rotation experienced by the SR (5.20 ± 3.93°) group compared to the MR (0.75 ± 5.12°) group. During ramp activities, the SR TKA consistently exhibited a significantly more posterior position of both condyles compared to the MR TKA.
  
  
  CONCLUSIONS
  Although the SR TKA exhibited larger amounts of axial rotation compared to the MR TKA in DKB, neither design exhibited weight-bearing kinematics as previously reported for the normal knee. Additional research on the normal knee for ramp activities is required to understand the importance of condylar position during these activities.
authors.affiliation: Center for Musculoskeletal Research, MABE Department, University of Tennessee, Knoxville, Tennessee.
authors.forename: Trevor F
authors.initials: TF
authors.lastname: Grieco
authors.affiliation: Center for Musculoskeletal Research, MABE Department, University of Tennessee, Knoxville, Tennessee.
authors.forename: Adrija
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Center for Musculoskeletal Research, MABE Department, University of Tennessee, Knoxville, Tennessee.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Komistek
authors.affiliation: Tennessee Orthopaedic Clinics, Knoxville, Tennessee.
authors.forename: Harold E
authors.initials: HE
authors.lastname: Cates
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D001696:Biomechanical Phenomena; D005471:Fluoroscopy; D006801:Humans; D007717:Knee / Q000601:surgery; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery*; D007720:Knee Prosthesis / Q000706:statistics & numerical data*; D008875:Middle Aged; D009068:Movement; D020370:Osteoarthritis, Knee / Q000601:surgery; D016059:Range of Motion, Articular; D012399:Rotation; D016138:Walking; D016474:Weight-Bearing
keywords: cruciate retaining; kinematics; mobile fluoroscopy; multiple radii; single radius; total knee arthroplasty