title: Midflexion instability in revision total knee arthroplasty.
abstract: Midflexion instability is a new concept associated with revision total knee arthroplasty. It appears as rotational instability with combined external rotation and valgus stress in a knee flexed between 45 degrees and 90 degrees. Three main factors contribute to this instability: anterior medial collateral ligament attenuation, femoral-tibial articular geometry, and tibial post-femoral box geometry. Rotational stress should be included when assessing stability intraoperatively to identify those patients who may require additional constraint.
authors.affiliation: Los Angeles Orthopaedic Institute, Los Angeles, California, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: McPherson
authors.forename: John
authors.initials: J
authors.lastname: Cuckler
authors.forename: Adolph V
authors.initials: AV
authors.lastname: Lombardi
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control*; D007720:Knee Prosthesis / Q000009:adverse effects*; D012086:Reoperation / Q000009:adverse effects