title: Causes of instability after total knee arthroplasty.
abstract: The purpose of the present study was to characterize the underlying causes that lead to instability after total knee arthroplasty (TKA). We reviewed 83 revision TKAs (79 patients) performed for instability. After detailed analysis of patient's history, physical examination, operative report and radiographs, we identified six categories: flexion/extension gap mismatch, component malposition, isolated ligament insufficiency, extensor mechanism insufficiency, component loosening, and global instability. Twenty-five knees presented with multi-factorial instability. When these knees were classified according to the most fundamental category, each category above included 24, 12, 11, 10, 10 and 16 knees respectively. The unstable TKA may result from a variety of distinct etiologies which must be identified and treated at the time of revision. The revision TKA could be tailored to the specific causes.
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Song
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, Redwood City, California.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Detch
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, Redwood City, California.
authors.forename: William J
authors.initials: WJ
authors.lastname: Maloney
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, Redwood City, California.
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Goodman
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, Redwood City, California.
authors.forename: James I
authors.initials: JI
authors.lastname: Huddleston
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology* / Q000628:therapy; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D012086:Reoperation; D016896:Treatment Outcome
keywords: cause; instability; knee; total knee arthroplasty