title: Preoperative prognosis score is a useful tool regarding eccentric rotational acetabular osteotomy in patients with acetabular dysplasia.
abstract: BACKGROUND
  It is unknown how possible preoperative factors influence the postoperative outcome of eccentric rotational acetabular osteotomy (ERAO). We aimed to determine these factors and to develop a scoring system for predicting the prognosis after ERAO in patients with symptomatic hip dysplasia.
  
  
  METHODS
  We included 700 patients (54 men, 646 women) who underwent ERAO during September 1989 to March 2013. The patients' clinical background, preoperative clinical findings, and preoperative imaging findings were examined retrospectively. Univariate and multivariate Cox regression were performed using the time from the day of surgery to a Harris hip score (HHS) <80 as an endpoint. A failure score was defined to predict the prognosis for an HHS <80, and its predictive capacity was assessed.
  
  
  RESULTS
  Ninety patients had an HHS <80. Forty-two patients underwent conversion to total hip arthroplasty (THA) after their HHS decreased to <80. Five factors were identified in relation to an HHS <80: a history of congenital dislocation of the hip, joint congruity, body mass index, the preoperative minimum joint space width, and the preoperative abduction range of motion. We estimated the weight of each factor using the results of multivariate Cox regression, and the outcome prediction scoring was obtained (0-17 points). For three groups of patients (total points of each factors: 0-5, 6-9, and ≥10 points), the Kaplan-Meier event-free survival rates at 15 years postoperatively for an HHS <80 were 97%, 81%, and 55%, respectively; the survival rates for THA conversion using this prediction scoring were 99%, 96%, and 85%, respectively.
  
  
  CONCLUSIONS
  Five preoperative factors can easily and clearly predict the prognosis following ERAO. The prognosis score may be a useful tool when making a decision regarding operative treatments in adult patients with acetabular dysplasia.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Japan. Electronic address: amano.takafumi@g.mbox.nagoya-u.ac.jp.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Amano
authors.affiliation: Department of Hip and Knee Reconstructive Surgery, Nagoya University Graduate School of Medicine, Japan.
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Japan.
authors.forename: Taisuke
authors.initials: T
authors.lastname: Seki
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Takegami
authors.affiliation: Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Murotani
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Japan; Center for Advanced Medicine and Clinical Research, Nagoya University Hospital, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D000328:Adult; D000704:Analysis of Variance; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods; D015331:Cohort Studies; D016001:Confidence Intervals; D018450:Disease Progression; D005260:Female; D006617:Hip Dislocation / Q000175:diagnosis* / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery*; D010027:Osteotomy / Q000009:adverse effects / Q000379:methods*; D010808:Physical Examination / Q000379:methods; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D016016:Proportional Hazards Models; D011475:Prosthesis Failure; D011859:Radiography / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome