title: What Is the Early/Mid-term Survivorship and Functional Outcome After Bernese Periacetabular Osteotomy in a Pediatric Surgeon Practice?
abstract: BACKGROUND
  The Bernese periacetabular osteotomy (PAO) is a recognized joint-preserving procedure. Achieving joint stability without creating impingement is important, but the orientation target that best balances these sometimes competing goals has not yet been clearly defined. Moreover, the learning curve of this challenging procedure has not been described.
  
  
  OBJECTIVE
  The purposes of this study were (1) to determine the 10-year survivorship and functional outcome after Bernese PAO in a single-surgeon series; (2) to review which patient, surgical, and radiographic factors might predict outcome after the procedure; and (3) to define the learning curve for target acetabular correction.
  
  
  METHODS
  The first 68 PAOs performed for symptomatic hip dysplasia were retrospectively evaluated. None have been lost to followup with followup less than 2 years. Endpoints for the lost to followup (n = 2) are at the time of when last seen. During the study period, the same surgeon performed 562 pelvic osteotomies (including Salter, Pemberton, Dega and Chiari) and 64 shelf acetabuloplasties. Bernese PAO was used only for symptomatic dysplasia (center-edge angle < 25° and nonhorizontal acetabular roof) in developmentally mature hips without evidence of major joint incongruence or subluxation. Most patients were female (n = 49 [60 hips, 88%]); mean age at operation was 25 years (SD 7). Sixteen hips had previous hip procedures. The study's mean followup was 8 years (range, 2-18 years). Patient-reported functional outcome was obtained using the WOMAC score (best-worst: 0-96). Radiographic parameters of dysplasia (acetabular index [AI], center-edge angle [CEA], congruency, Tönnis grade, and joint space) were evaluated from preoperative and postoperative radiographs using computer software.
  
  
  RESULTS
  The 10-year survival rate was 93% (95% confidence interval [CI], 82%-100%); four patients underwent further surgery to the hip in the study period. The mean WOMAC was 12 (range, 0-54). Factors that influenced survival included joint congruency (100% versus 78%; 95% CI, 61%-96%; p = 0.03) and acetabular orientation correction achieved (AIpostoperative < 15° [100% versus 65%; 95% CI, 43-88; p < 0.001] and CEApostoperative 20° to 40° [100% versus 71.9%; 52.8-100; p < 0.001]). Better WOMAC scores were seen if postoperative AI < 15° (7 versus 25, p = 0.005) and CEA between 20° and 40° (7 versus 23, p = 0.005) were achieved. The chances of obtaining acetabular correction within this range improved after the 20(th) procedure (30% versus 70%, p = 0.008).
  
  
  CONCLUSIONS
  This study reports excellent results after Bernese PAO in the hands of an experienced pediatric hip surgeon. We advocate cautious correction of the acetabular fragment. Future studies should concentrate on how to determine what the optimal target is and how to achieve it intraoperatively, minimizing the learning curve associated with it.
  
  
  METHODS
  Level III, therapeutic study.
authors.affiliation: Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
authors.forename: George
authors.initials: G
authors.lastname: Grammatopoulos
authors.affiliation: Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Wales
authors.affiliation: Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
authors.forename: Alpesh
authors.initials: A
authors.lastname: Kothari
authors.affiliation: University of Bath, Bath, UK.
authors.forename: Harinderjit S
authors.initials: HS
authors.lastname: Gill
authors.affiliation: Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wainwright
authors.affiliation: Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK. tim.theologis@ouh.nhs.uk.
authors.forename: Tim
authors.initials: T
authors.lastname: Theologis
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001696:Biomechanical Phenomena; D002983:Clinical Competence; D004185:Disability Evaluation; D005260:Female; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D059032:Learning Curve; D008297:Male; D010027:Osteotomy / Q000009:adverse effects / Q000193:education; D010147:Pain Measurement; D011183:Postoperative Complications / Q000503:physiopathology / Q000601:surgery; D011859:Radiography; D020127:Recovery of Function; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult