title: Incidence of patellar clunk with a modern posterior-stabilized knee design.
abstract: Patellar clunk is an uncommon complication of posterior-stabilized total knee arthroplasty (TKA), though the incidence has been reported to be as high as 7.5% with some posterior-stabilized implants, and the etiology is multifactorial. Femoral component design has been implicated as a major cause of this complication. This series compares the incidence of patellar clunk with 2 different knee prostheses, the Insall-Burstein II (IB) and the NexGen Legacy PS (NG), both manufactured by Zimmer (Warsaw, Ind). One-hundred fifty consecutive posterior-stabilized TKAs were in each group, and the groups were similar in surgical approaches and techniques. Insall-Salvati (IS) ratios and joint-line positions were measured on preoperative and postoperative x-rays. Knee Society Clinical and Functional scores were calculated. Incidence of patellar clunk was reduced from 4% with the IB design to 0% with the NG design. IS ratios, joint-line positions, and clinical outcomes were no different between the groups. It appears that femoral component design may play a substantial role in development of patellar clunk after posterior-stabilized TKA.
authors.affiliation: Pennsylvania Hospital, Philadelphia, PA, USA. LonnerJ@pahosp.com
authors.forename: Jess H
authors.initials: JH
authors.lastname: Lonner
authors.forename: Jeff G
authors.initials: JG
authors.lastname: Jasko
authors.forename: Hari P
authors.initials: HP
authors.lastname: Bezwada
authors.forename: David G
authors.initials: DG
authors.lastname: Nazarian
authors.forename: Robert E
authors.initials: RE
authors.lastname: Booth
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D015994:Incidence; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000503:physiopathology*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000503:physiopathology*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D016896:Treatment Outcome