title: Revision total knees done for extensor problems frequently require reoperation.
abstract: We retrospectively reviewed 361 patients who had a revision total knee arthroplasty done for an extensor mechanism problem to assess the prevalence, etiology, and risk factors for subsequent reoperation. The prevalence of reoperation was 23% because 84 patients were reoperated on one or more times. The average time to the first reoperation was 2.4 years. The total number of reoperations was 127 with 58 patients reoperated on once, 15 reoperated on twice, and 11 reoperated on three or more times. The cumulative risk of a reoperation for any reason after index revision was 7% at 1 year, 19.6% at 5 years, and 35.9% at 10 years. The most common reason for reoperation was a new or recurrent patellofemoral problem, which accounted for 33% of the first reoperations. The risk of reoperation was substantially lower for patients that had femoral or tibial component malrotation corrected at the time of revision TKA. The risk of reoperation after revision TKA for an extensor mechanism complication increased in patients operated on in the 1990s compared with patients operated on in the 1970s and 1980s.
  
  
  METHODS
  Therapeutic study, Level-IV-1 (case series). See the Guidelines for authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: William P
authors.initials: WP
authors.lastname: Cooney
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Sierra
authors.forename: Robert T
authors.initials: RT
authors.lastname: Trousdale
authors.forename: Mark W
authors.initials: MW
authors.lastname: Pagnano
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D005269:Femur / Q000503:physiopathology; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007720:Knee Prosthesis; D046788:Patellofemoral Pain Syndrome / Q000601:surgery*; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia / Q000503:physiopathology