title: Fluoroscopic and computed tomographic analysis of knee kinematics during very deep flexion after total knee arthroplasty.
abstract: We examined the relative motion of femoral and tibial total knee arthroplasty components and the difference between 2 different tibial inserts (9 flat types and 7 dish types) in patients sitting in very deep flexion. X-ray, fluoroscopic examination, and computed tomography were used to analyze liftoff, and rotation. During seiza-style sitting, one knee (11%) with the flat insert lifted off on the medial side and 5 knees (71%) with the dish-type insert showed liftoff. The tibial internal rotation angles were 17.2 degrees +/- 4.1 degrees (flat type) and 11.7 degrees +/- 3.1 degrees (dish type) (P < .05). The flat type showed less liftoff at the medial side and more internal rotation. For very deep flexion, components that tolerate larger rotational freedom are favorable.
authors.affiliation: Faculty of Medicine, Department of Orthopedic Surgery, Kyoto University, Kyoto, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakamura
authors.forename: Haruki
authors.initials: H
authors.lastname: Takagi
authors.forename: Taiyo
authors.initials: T
authors.lastname: Asano
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D005471:Fluoroscopy; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000502:physiology* / Q000601:surgery; D007720:Knee Prosthesis; D020370:Osteoarthritis, Knee / Q000534:rehabilitation / Q000601:surgery*; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome