title: Dislocation of posterior-stabilized mobile-bearing knee prosthesis. A case report.
abstract: Spin-out of mobile-bearing knees is a significant early complication of mobile-bearing total knee arthroplasty. Dislocation of the cam-post mechanism of fixed-bearing posterior-stabilized knees occurs more rarely. We have observed an unusual case of dislocation of posterior-stabilized rotating-platform total knee arthroplasty, which has both a cam-post mechanism and rotating platform. A 65-year-old man with knee osteoarthritis and cervical spondylotic myelopathy underwent total knee arthroplasty using a mobile-bearing prosthesis. The dislocation, which occurred 4 days postoperatively, could not be reduced by closed manipulation. However, spontaneous reduction occurred 6 days after the dislocation, which did not recur. A gap mismatch or trapezoidal-shaped gaps may lead to dislocation or spin-out of the bearing insert. This case illustrates that dislocation of a posterior-stabilized mobile-bearing total knee arthroplasty can occur, and both quadriceps deficiency and ligament laxity may contribute to the risk of dislocation.
authors.affiliation: Department of Orthopaedic Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu City, Mie 514-8507, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sudo
authors.forename: Aki
authors.initials: A
authors.lastname: Fukuda
authors.forename: Atsumasa
authors.initials: A
authors.lastname: Uchida
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery; D011474:Prosthesis Design; D011475:Prosthesis Failure