title: In-vivo knee kinematics in rotationally unconstrained total knee arthroplasty.
abstract: Total knee replacement designs claim characteristic kinematic performance that is rarely assessed in patients. In the present study, in vivo kinematics of a new prosthesis design was measured during activities of daily living. This design is posterior stabilized for which spine-cam interaction coordinates free axial rotation throughout the flexion-extension arc by means of a single radius of curvature for the femoral condyles in the sagittal and frontal planes. Fifteen knees were implanted with this prosthesis, and 3D video-fluoroscopic analysis was performed at 6-month follow-up for three motor tasks. The average range of flexion was 70.1° (range: 60.1-80.2°) during stair-climbing, 74.7° (64.6-84.8°) during chair-rising, and 64.1° (52.9-74.3°) during step-up. The corresponding average rotation on the tibial base-plate of the lines between the medial and lateral contact points was 9.4° (4.0-22.4°), 11.4° (4.6-22.7°), and 11.3° (5.1-18.0°), respectively. The pivot point for these lines was found mostly in the central area of the base-plate. Nearly physiological range of axial rotation can be achieved at the replaced knee during activities of daily living.
authors: Department of Orthopedic Surgery, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors: Fabio
authors: F
authors: Catani
authors: Claudio
authors: C
authors: Belvedere
authors: Andrea
authors: A
authors: Ensini
authors: Alessandro
authors: A
authors: Feliciangeli
authors: Sandro
authors: S
authors: Giannini
authors: Alberto
authors: A
authors: Leardini
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged