title: A Modification of the Dunn Osteotomy With Preservation of the Ligamentum Teres.
abstract: BACKGROUND
  We aimed to determine if a modified Dunn osteotomy could be safely performed without surgical dislocation and consequent preservation of the ligamentum teres.
  
  
  METHODS
  All patients undergoing a modified Dunn osteotomy for a slipped capital femoral epiphysis over an 8-year period were included in this study, and all had a severe slip with an open physis.
  
  
  RESULTS
  The modified Dunn procedure was performed on 34 hips in 34 patients. The mean age was 13.1 years (range, 11 to 16 y) with a mean follow-up time of 54 months (range, 15 to 102 mo). All slips were severe (grade 3) with a mean slip angle of 73.2 degrees (range, 60 to 90 degrees). Nineteen slips were stable and 15 were unstable. Of the unstable slips, the average time from initial presentation to the emergency department until surgery was 9.4 days (range, 2 to 42 d). Excluding 1 patient who developed complete collapse of the femoral head (NAHS 56), the average Nonarthritic Hip score was 98 (range, 93.7 to 100). Four (11.8%) patients developed avascular necrosis of the femoral head, of which 3 were unstable slips.
  
  
  CONCLUSIONS
  A modified Dunn osteotomy with preservation of the ligamentum teres allows an excellent restoration of the anatomic alignment of the femoral head and neck. Rates of AVN are not increased compared with other techniques of subcapital osteotomy but this complication cannot be eliminated particularly in patients with unstable slips.
  
  
  METHODS
  Level III.
authors.affiliation: Royal Orthopaedic Hospital, Birmingham, UK.
authors.forename: Navi
authors.initials: N
authors.lastname: Bali
authors.forename: James
authors.initials: J
authors.lastname: Harrison
authors.forename: Edward
authors.initials: E
authors.lastname: Laugharne
authors.forename: C Edward
authors.initials: CE
authors.lastname: Bache
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D005271:Femur Head Necrosis / Q000209:etiology; D006801:Humans; D008297:Male; D059351:Organ Sparing Treatments / Q000379:methods*; D010027:Osteotomy / Q000379:methods*; D012189:Retrospective Studies; D000069590:Round Ligaments; D012720:Severity of Illness Index; D060048:Slipped Capital Femoral Epiphyses / Q000150:complications / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome