title: Double-concave deformity of the polyethylene tibial post in posterior stabilized total knee arthroplasty.
abstract: This report describes a unique case of bilateral total knee arthroplasty necessitating revision of the polyethylene insert, which showed prominent marks on the tibial post resulting from repeated seiza-style sitting. The patient presented 7 years postoperatively with knee pain and flexion disturbance due to continuous joint effusion persisting for more than 4 months. Proliferating synovia throughout the joint revealed reactive synovitis to polyethylene particles. The retrieved polyethylene inserts displayed double-concave deformity of the tibial post with burnishing and creep in tibiofemoral articulation. The damage pattern of retrieved polyethylene inserts reflected the data from tibiofemoral contact location obtained using a shape-matching technique in the early postoperative phase. This case provides an example of damage to the polyethylene tibial post caused by a floor-sitting lifestyle and the potential clinical sequelae.
authors.affiliation: Department of Orthopaedic Surgery, Keio University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Niki
authors.forename: Hideo
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Yoshimine
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Suda
authors.forename: Scott A
authors.initials: SA
authors.lastname: Banks
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D003469:Culture; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007720:Knee Prosthesis; D008019:Life Style; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011475:Prosthesis Failure; D016059:Range of Motion, Articular / Q000502:physiology; D012086:Reoperation; D013977:Tibia
chemical_list: D020959:Polyethylene