title: Coronal plane stability before and after total knee arthroplasty.
abstract: The success of total knee arthroplasty depends in part on proper soft tissue management to achieve a stable joint. It is unknown to what degree total knee arthroplasty changes joint stability. We used a surgical navigation system to intraoperatively measure joint stability in 24 patients under going primary total knee arthroplasty to address two questions: (1) Is the total arc of varus-valgus motion after total knee arthroplasty different from the arc of varus-valgus motion in an osteoarthritic knee? (2) Does total knee arthroplasty produce equal amounts of varus/valgus motion (ie, is the knee "balanced")? We observed no difference between the total arc of varus-valgus motion before and after total knee arthroplasty; the total amount of motion was unchanged. On average, osteoarthritic knees were "unbalanced" but were "balanced" after prosthesis implantation. We found a negative correlation between the relative amount of varus/valgus motion in extension before and after prosthesis implantation in extension and a positive correlation between how well the knees were balanced after prosthesis implantation in extension and in flexion. Our data suggest immediately after implantation knees retain a greater than normal amount of varus-valgus motion, but this motion is more evenly distributed.
authors.affiliation: Mechanical Engineering Department, Stanford University, Stanford, CA, USA. siston.1@stanford.osu.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Siston
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Goodman
authors.forename: Scott L
authors.initials: SL
authors.lastname: Delp
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Giori
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001696:Biomechanical Phenomena; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery; D011183:Postoperative Complications / Q000209:etiology* / Q000503:physiopathology; D011446:Prospective Studies; D016059:Range of Motion, Articular; D012399:Rotation; D025321:Surgery, Computer-Assisted; D016896:Treatment Outcome