title: Patellofemoral osteoarthritis after Insall's proximal realignment for recurrent patellar dislocation.
abstract: OBJECTIVE
  The aim of the present study was to retrospectively investigate the development of patellofemoral osteoarthritis after the historical Insall's proximal realignment for patellar stabilisation in patients with recurrent patellar dislocation. Furthermore, risk factors for recurrent patellar dislocation and for patellofemoral osteoarthritis development were evaluated.
  
  
  METHODS
  Forty-two patients underwent patellofemoral stabilising surgery by the historic Insall's proximal realignment; they were evaluated with a mean follow-up period of 52 months. Plain radiography was used to document osteoarthritic changes by using the Iwano classification. MRIs obtained at the latest follow-up were evaluated for patellofemoral cartilage lesions. Univariate and multivariate logistic regression analyses were performed to evaluate the influence of trochlear dysplasia, tibial tubercle-trochlear groove distance and patellar height on redislocation. Pearson's χ (2) and the Spearman's correlation tests were used to assess a possible correlation between trochlear dysplasia and patellar dislocation, as well as between instability and development of patellofemoral osteoarthritis.
  
  
  RESULTS
  At the latest follow-up, plain radiographs showed a significant increase in patellofemoral osteoarthritis (grades II-IV according to the Iwano classification) in 18 patients (43%) compared with 4 patients (10%) at the time of surgery (P = 0.001). Patellofemoral cartilage lesions (grades II-IV) were detected in 18 patients (43 %) on MRI. Nine patients (21%) had at least one incidence of redislocation at follow-up. Estimated redislocation-associated risk factors could not be determined. Trochlear dysplasia had a significant impact on patellofemoral osteoarthritis development (P = 0.001), whereas recurrent patellar instability had none (n.s.).
  
  
  CONCLUSIONS
  Insall's proximal realignment technique leads to a significant progression of patellofemoral osteoarthritis. No risk factors for redislocation could be found; however, the presence of trochlear dysplasia did correlate with patellofemoral osteoarthritis.
  
  
  METHODS
  IV.
authors.affiliation: Department of Orthopaedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany.
authors.forename: Karl F
authors.initials: KF
authors.lastname: Schüttler
authors.forename: Johannes
authors.initials: J
authors.lastname: Struewer
authors.forename: Philip P
authors.initials: PP
authors.lastname: Roessler
authors.forename: Markus
authors.initials: M
authors.lastname: Gesslein
authors.forename: Marga B
authors.initials: MB
authors.lastname: Rominger
authors.forename: Ewgeni
authors.initials: E
authors.lastname: Ziring
authors.forename: Turgay
authors.initials: T
authors.lastname: Efe
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010329:Patella / Q000601:surgery; D031222:Patellar Dislocation / Q000601:surgery*; D057071:Patellofemoral Joint / Q000601:surgery*; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
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