title: Incidence and reasons for nonrevision reoperation after total knee arthroplasty.
abstract: BACKGROUND
  A dramatic increase in the demand for TKA is expected. The current burden of revision TKA is well known but the incidence and etiology of nonrevision reoperations after primary TKA is not.
  
  
  OBJECTIVE
  We determined the rate, reason, timing, and predictors of nonrevision reoperation after TKA.
  
  
  METHODS
  Using our institutional joint arthroplasty database, we identified 10,188 TKA performed on 7,613 patients between April 2000 and March 2008. A nonrevision reoperation was defined as any procedure requiring anesthetic in which components with bony interfaces were not removed or exchanged. Procedures after revision TKA were excluded. Potential risk factors investigated included age, gender, laterality, and simultaneous bilateral versus staged bilateral versus unilateral TKA. The minimum followup was 1 year (median, 4.1 years; range, 1.1 to 9.1 years).
  
  
  RESULTS
  Three hundred fifty-three patients of 7,613 (4.6%) underwent 434 nonrevision reoperations on 384 of 10,188 (3.8%) knees. The most common indication for nonrevision reoperation was stiffness (58%; 252 of 434), followed by patellar clunk (12%; 53), infection (12%; 52), wound revision (6%; 26), hematoma (4.4%; 19), among others. The median time to reoperation was 74.5 days (range, 1-3058 days) but varied widely. Younger patients and those with unilateral TKA were more likely to have a nonrevision reoperation.
  
  
  CONCLUSIONS
  The majority of nonrevision reoperations are performed for stiffness. Patellar clunk and infection also result in a large number of nonrevision reoperations. In weighing the future economic and workforce burden of TKA, nonrevision reoperations need to be acknowledged, and preventive measures need to be implemented.
  
  
  METHODS
  Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: The Rothman Institute of Orthopaedics at Thomas Jefferson University Hospital, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Zmistowski
authors.forename: Camilo
authors.initials: C
authors.lastname: Restrepo
authors.forename: Lauren K
authors.initials: LK
authors.lastname: Kahl
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
authors.forename: Peter F
authors.initials: PF
authors.lastname: Sharkey
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation; D016009:Chi-Square Distribution; D005260:Female; D006406:Hematoma / Q000209:etiology / Q000601:surgery; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D015143:Philadelphia; D011183:Postoperative Complications / Q000209:etiology / Q000601:surgery*; D016459:Prosthesis-Related Infections / Q000209:etiology / Q000601:surgery; D012042:Registries; D012086:Reoperation; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome