title: Classification of trochlear dysplasia as predictor of clinical outcome after trochleoplasty.
abstract: OBJECTIVE
  Sulcus-deepening trochleoplasty restores the trochlear groove in patients with patellofemoral instability and underlying trochlear dysplasia. There are types of dysplasia both with (B and D) and without (A and C) a supratrochlear spur. The aim of this study was to identify influencing factors for the clinical outcome following trochleoplasty.
  
  
  METHODS
  Forty-four knees in 38 patients who underwent trochleoplasty for instability (type A in 9, B in 15, C in 9 and D in 11 knees) were assessed clinically with the Kujala score and radiologically with radiographs and MRI. The median follow-up was 4 (2-7.8) years.
  
  
  RESULTS
  At follow-up, the median Kujala score had improved from 68 (29-84) to 90 (42-100) points (P < 0.001). Instability (P < 0.001) and pain (P = 0.027) decreased significantly, but in 3 knees, pain was worse postoperatively. Twenty-seven knees were ranked as excellent, 10 as good, 2 as fair and 5 as poor. Overall, dysplasia types B and D benefited more from surgery than types A and C. The postoperative MRI revealed no chondrolysis or subchondral necrosis, but deterioration of cartilage on the lateral trochlear facet was identified.
  
  
  CONCLUSIONS
  Trochleoplasty is a useful and reliable surgical technique to improve patellofemoral instability in patients with a dysplastic trochlea. While improved stability is predictable, pain is less predictable and may even increase following surgery. The overall results were directly dependent on the type of the dysplasia, with a significantly better clinical outcome in type B and D. The clinical relevance of this study is that severe dysplasia can successfully be treated with trochleoplasty.
  
  
  METHODS
  III.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Balgrist, Zurich, Forchstr. 340, 8008, Zurich, Switzerland. sandro.fucentese@balgrist.ch
authors.forename: Sandro F
authors.initials: SF
authors.lastname: Fucentese
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Zingg
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schmitt
authors.forename: Christian W A
authors.initials: CW
authors.lastname: Pfirrmann
authors.forename: Dominik C
authors.initials: DC
authors.lastname: Meyer
authors.forename: Peter P
authors.initials: PP
authors.lastname: Koch
mesh_terms: D000293:Adolescent; D000328:Adult; D001178:Arthroplasty / Q000379:methods*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000601:surgery*; D008297:Male; D057071:Patellofemoral Joint / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult