title: Computer-assisted navigation in patellofemoral arthroplasty: a new technique to improve rotational position of the trochlea.
abstract: BACKGROUND
  Maltracking or subluxation is one of the complications of patellofemoral arthroplasty.
  
  
  OBJECTIVE
  We questioned whether the computed navigation system can improve patellar tracking in patients with patellofemoral arthroplasty (PFA).
  
  
  METHODS
  Between 2007 and 2010 we performed 15 patellofemoral arthroplasties using the Ceraver PFA and navigation assistance. Fifteen other patients underwent surgery without navigation during the same period and acted as a control group. The rotation of the native trochlea as measured using the epicondylar line as a reference before surgery and the rotation of the trochlear component and the trochlear twist angle were assessed with computed tomography (CT) scan after surgery.
  
  
  RESULTS
  The mean follow-up was 3 years (range, 2-5 years). The group with navigation had no patellofemoral complications and better clinical scores. The group without navigation had abnormal patellofemoral tracking in 5 of the 15 patients. CT scan demonstrated excessive internal component rotation, as compared with patients without complications. This excessive internal rotation was proportional to the severity of the patellofemoral maltracking.
  
  
  CONCLUSIONS
  The short-term results suggest that navigation can lead to better trochlear rotation which, in our hands, is associated with fewer cases of patellar maltracking and better overall clinical scores.
authors.affiliation: Hospital Henri Mondor, Avenue du Marechal de Lattre de Tassigny, Creteil, 94000 France ; University Paris East, 61 Avenue du Général de Gaulle, Creteil, 94010 France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Hernigou
authors.affiliation: Hospital Henri Mondor, Avenue du Marechal de Lattre de Tassigny, Creteil, 94000 France ; University Paris East, 61 Avenue du Général de Gaulle, Creteil, 94010 France.
authors.forename: Charles Henri
authors.initials: CH
authors.lastname: Flouzat-Lachaniette
authors.affiliation: Hospital Henri Mondor, Avenue du Marechal de Lattre de Tassigny, Creteil, 94000 France ; University Paris East, 61 Avenue du Général de Gaulle, Creteil, 94010 France.
authors.forename: William
authors.initials: W
authors.lastname: Delblond
authors.affiliation: Hospital Henri Mondor, Avenue du Marechal de Lattre de Tassigny, Creteil, 94000 France ; University Paris East, 61 Avenue du Général de Gaulle, Creteil, 94010 France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Duffiet
authors.affiliation: Hospital Henri Mondor, Avenue du Marechal de Lattre de Tassigny, Creteil, 94000 France ; University Paris East, 61 Avenue du Général de Gaulle, Creteil, 94010 France.
authors.forename: Didier
authors.initials: D
authors.lastname: Julian
keywords: computer-assisted navigation; knee; patella; patellofemoral arthroplasty