title: A posterior-stabilized total knee arthroplasty shows condylar lift-off during deep knee bends.
abstract: This prospective randomized study was done to examine whether any difference in presentation of condyler lift-off exists between posterior cruciate-retaining and posterior-stabilized total knee arthroplasties. Fluoroscopic analysis of flexion kinematics under weightbearing condition was done for 18 patients who had bilateral paired total knee arthroplasties. The posterior cruciate-retaining and posterior-stabilized prostheses were from the same total knee arthroplasty series with comparable surface geometries and were implanted by one surgeon. At evaluation, five of 18 patients (28%) with posterior cruciate-retaining total knee arthroplasties had condylar lift-off, compared with 12 of 18 patients (67%) with posterior-stabilized total knee arthroplasties. Consequently, a significant difference in its incidence was seen between the groups. Condylar lift-off in posterior-stabilized knees was observed at various flexion angles, and one knee in this group had lift-off laterally and medially at different flexion angles. These findings raise concern that the higher incidence of condylar lift-off in posterior-stabilized total knee arthroplasty may lead to an increased wear rate of polyethylene associated with long-term prosthetic loosening.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Sang Yang
authors.initials: SY
authors.lastname: Lee
authors.forename: Nobuzo
authors.initials: N
authors.lastname: Matsui
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
authors.forename: Richard D
authors.initials: RD
authors.lastname: Komistek
authors.forename: Mohamed
authors.initials: M
authors.lastname: Mahfouz
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Dennis
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshiya
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000502:physiology; D005471:Fluoroscopy; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology