title: A reduction in body mass index lowers risk for bilateral slipped capital femoral epiphysis.
abstract: BACKGROUND
  Slipped capital femoral epiphysis (SCFE) is occurring in greater numbers, at increasingly younger ages, and more frequently bilaterally (BL-SCFE). Obesity is one risk factor for SCFE. However, it is unclear whether postoperative decreases or increases in body mass index (BMI) alter the risk of subsequent contralateral SCFE.
  
  
  OBJECTIVE
  We therefore determined whether (1) BMI percentile was a risk factor for BL-SCFE; and (2) postoperative increases and/or decreases in BMI percentile influenced the risk for BL-SCFE.
  
  
  METHODS
  We retrospectively reviewed the records of 502 patients surgically treated for SCFE and identified 138 (27%) with BL-SCFE and 364 (73%) with unilateral SCFE (UL-SCFE); 173 patients, 60 (35%) with BL-SCFE and 113 (65%) with UL-SCFE met our inclusion criteria. Risk factors included sex, age, slip stability, slip chronicity, slip angle, and obesity. Percentile BMI was recorded at the time of first SCFE surgery, at the time of last followup for patients undergoing UL-SCFE, and at the time of second SCFE surgery for patients undergoing BL-SCFE.
  
  
  RESULTS
  Sex, age, slip stability, and slip angle were not associated with BL-SCFE. Postoperative obesity (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.2-9.7) and acute slip chronicity (OR, 2.9; 95% CI, 1.3-6.7) had higher risks for sequential BL-SCFE. Obese patients who became nonobese postoperatively had a decreased risk of sequential BL-SCFE compared with those who remained obese (OR, 0.16; 95% CI, 1.2-116.5).
  
  
  CONCLUSIONS
  Only postoperative obesity and an acute slip were risk factors for sequential BL-SCFE. BMI reduction to lower than the 95% percentile after SCFE surgery was associated with lower risk for BL-SCFE development. The data suggest early supervised therapeutic weight management programs for patients treated for UL-SCFE are important to reduce risk of subsequent SCFE.
  
  
  METHODS
  Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors: Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA, USA.
authors: Adam Y
authors: AY
authors: Nasreddine
authors: Benton E
authors: BE
authors: Heyworth
authors: David
authors: D
authors: Zurakowski
authors: Mininder S
authors: MS
authors: Kocher
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D002648:Child; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000628:therapy*; D016017:Odds Ratio; D019637:Orthopedic Procedures / Q000009:adverse effects; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control*; D011859:Radiography; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D060048:Slipped Capital Femoral Epiphyses / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D015431:Weight Loss
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