title: Avascular necrosis most common indication for hip arthroplasty in patients with slipped capital femoral epiphysis.
abstract: BACKGROUND
  Recently, much attention has been focused on the prevention of arthritis after slipped capital femoral epiphysis (SCFE). Little, however, is published on which subset of SCFE patients eventually require hip replacement, how soon arthroplasty is required, and the long-term outcomes after arthroplasty.
  
  
  METHODS
  A hip registry database at a tertiary referral center was searched for all primary hip arthroplasties in patients with a confirmed childhood diagnosis of SCFE.
  
  
  RESULTS
  From 1954-2007, 38 hips in 33 patients underwent arthroplasty, including total hip arthroplasty (28), hip resurfacing (8), and hemiarthroplasty (2) for the diagnosis of SCFE. During this time period, over 33,000 primary total hip arthroplasties were carried out at our center. Underlying diagnoses included avascular necrosis or chondrolysis in 25 hips and degenerative changes and/or impingement in 13 hips. The slip severity in 20 cases was severe, 4 moderate, 7 mild, and 7 hips had unknown slip severity. Half of the slips (7/14) in the degenerative group were mild or moderate. Fourteen (70%) of the 20 severe slips and 10 (71%) of the 14 acute or acute-on-chronic slips presented for arthroplasty with the diagnosis of avascular necrosis. Avascular necrosis was associated with a severe slip (P=0.03) and an acute or acute-on-chronic presentation (P=0.008). With the exception of 2 mild slips treated nonoperatively, all slips underwent either pin fixation (27) or primary osteotomy (9). Mean time from slip to arthroplasty was 7.4 years in patients with AVN or chondrolysis, compared with 23.6 years in patients with degenerative change (P<0.0002). Mean age at arthroplasty was 20 years in the AVN or chondrolysis group compared with 38 years in the degenerative group (P<0.0001). Sixteen hips required revision arthroplasty at a mean of 11.6 years postoperatively, most commonly for component loosening and/or polyethylene wear. Kaplan Meier 5-year survival free from revision for all causes was 87% overall and 95% in the total hip arthroplasty subset.
  
  
  CONCLUSIONS
  The majority of hip arthroplasties in patients with slipped capital femoral epiphysis were carried out for the indication of avascular necrosis rather than degenerative changes related to femoroacetabular impingement. We found a moderately high revision rate in SCFE patients undergoing total hip arthroplasty or other joint replacement.
  
  
  METHODS
  IV, case series.
authors.affiliation: Department of Orthopedics, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Annalise Noelle
authors.initials: AN
authors.lastname: Larson
authors.forename: Amy L
authors.initials: AL
authors.lastname: McIntosh
authors.forename: Robert T
authors.initials: RT
authors.lastname: Trousdale
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
mesh_terms: D000293:Adolescent; D019644:Arthroplasty, Replacement, Hip; D002648:Child; D004839:Epiphyses, Slipped / Q000150:complications* / Q000601:surgery*; D005260:Female; D005270:Femur Head; D005271:Femur Head Necrosis / Q000209:etiology* / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012189:Retrospective Studies