title: Minimally invasive periacetabular osteotomy using a modified Smith-Petersen approach: technique and early outcomes.
abstract: OBJECTIVE
  Periacetabular osteotomy is an effective way of treating symptomatic hip dysplasia. We describe a new minimally invasive technique using a modification of the Smith-Peterson approach. We performed a prospective, longitudinal cohort study to assess for any compromise in acetabular correction when using this approach, and to see if the procedure would have a higher complication rate than that quoted in the literature for other approaches. We also assessed for any improvement in functional outcome.
  
  
  METHODS
  From 168 consecutive patients (189 hips) who underwent acetabular correction between March 2010 and March 2013 we excluded those who had undergone previous pelvic surgery for DDH and those being treated for acetabular retroversion. The remaining 151 patients (15 men, 136 women) (166 hips) had a mean age of 32 years (15 to 56) and the mean duration of follow-up was 2.8 years (1.2 to 4.5). In all 90% of cases were Tönnis grade 0 or 1. Functional outcomes were assessed using the Non Arthritic Hip Score (NAHS), University of California, Los Angeles (UCLA) and Tegner activity scores.
  
  
  RESULTS
  The mean pre-operative lateral centre-edge angle was 14.2° (-5° to 30°) and the mean acetabular index was 18.4° (4° to 40°). Post-operatively these were 31° (18° to 46°) and 3° (-7° to 29°), respectively, a significant improvement in both (p < 0.001). Allogenic blood transfusion was required in two patients (1.2%). There were no major nerve or vascular complications, and no wound infections. At the time of last follow-up, we noted a significant improvement in functional outcome scores: UCLA improved by 2.31 points, Tegner improved by 1.08 points, and the NAHS improved by 25.4 points (p < 0.001 for each). Hypermobility and longer duration of surgery were significant negative predictors for a good post-operative UCLA score, while residual retroversion was a positive predictor of post-operative UCLA score.
  
  
  CONCLUSIONS
  We have found this approach to be safe and effective, facilitating early recovery from surgery. Cite this article: Bone Joint J 2017;99-B:22-8.
authors.affiliation: University College London Hospitals NHS Foundation Trust, 235 Euston Rd, Fitzrovia, London NW1 2BU, UK.
authors.forename: O H
authors.initials: OH
authors.lastname: Khan
authors.affiliation: Northumbria Healthcare NHS Foundation Trust, Woodhorn Lane, Ashington NE63 9JJ, UK.
authors.forename: A
authors.initials: A
authors.lastname: Malviya
authors.affiliation: University College London Hospitals NHS Foundation Trust, 235 Euston Rd, Fitzrovia, London NW1 2BU, UK.
authors.forename: P
authors.initials: P
authors.lastname: Subramanian
authors.affiliation: John Flynn Private Hospital, 42 Inland Drive, Tugun, Queensland, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Agolley
authors.affiliation: University College London Hospitals NHS Foundation Trust, 235 Euston Rd, Fitzrovia, London NW1 2BU, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Witt
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000293:Adolescent; D000328:Adult; D016063:Blood Loss, Surgical; D005260:Female; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007902:Length of Stay; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D010027:Osteotomy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D017060:Patient Satisfaction; D011446:Prospective Studies; D011859:Radiography; D016896:Treatment Outcome; D055815:Young Adult
keywords: Functional outcome; Hip dysplasia; Minimally invasive surgery; Periacetabular osteotomy; Surgical approach; Young adult hip