title: Contact stress at the post-cam mechanism in posterior-stabilised total knee arthroplasty.
abstract: We measured the contact areas and contact stresses at the post-cam mechanism of a posterior-stabilised total knee arthroplasty when a posterior force of 500 N was applied to the Kirschner Performance, Scorpio Superflex, NexGen LPS Flex Fixed, and NexGen LPS Flex Mobile knee systems. Measurements were made at 90 degrees, 120 degrees, and 150 degrees of flexion both in neutral rotation and 10 degrees of internal rotation of the tibial component. Peak contact stresses at 90 degrees, 120 degrees, and 150 degrees were 24.0, 33.9, and 28.8 MPa, respectively, for the Kirschner; 26.0, 32.4, and 22.1 MPa, respectively, for the Scorpio; and 34.1, 31.5, and 32.5 MPa, respectively, for the NexGen LPS Flex Fixed. With an internally rotated tibia, the contact stress increased significantly with all the fixed-bearing arthroplasties but not with the NexGen LPS Flex Mobile arthroplasty. The post-cam design should be modified in order to provide a larger contact area whilst avoiding any impingement and edge loading.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakayama
authors.forename: S
authors.initials: S
authors.lastname: Matsuda
authors.forename: H
authors.initials: H
authors.lastname: Miura
authors.forename: Y
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: H
authors.initials: H
authors.lastname: Higaki
authors.forename: K
authors.initials: K
authors.lastname: Otsuka
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007720:Knee Prosthesis; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D013314:Stress, Mechanical