title: Assessing joint line positions by means of the contralateral knee: a new approach for planning knee revision surgery?
abstract: OBJECTIVE
  Reconstructing the natural joint line in knee revision surgery improves clinical and functional outcome but may be challenging when both cartilage and bone were removed during previous operations. Assessing joint lines (JLs) by means of bony landmarks is inadvisable because of large variations in human anatomy. Because of the inherent symmetry of the human body, we hypothesised that JLs may be directly assessed by measuring the distances from the bony landmarks to the JL of the contralateral knee by means of radiographic images.
  
  
  METHODS
  Using scaled weight-bearing radiographs in anteroposterior view of both knees, two independent observers measured the distances from the fibular head, the medial and lateral epicondyle, and the adductor tubercle to the JL. A two-sided p value of ≤0.05 was considered statistically significant.
  
  
  RESULTS
  Two hundred knees of 100 patients (50 men and 50 women) were examined. For the fibular head, the mean difference between the treated and the control knee was 0.0 mm with narrow confidence limits ranging from -1.1 to 1.1.
  
  
  CONCLUSIONS
  As a new assessment method, we have suggested to assess the JL by means of radiographs of the contralateral knee. The most precise parameter was found to be the distance between the fibular head and the JL. The level of arthritis, age, gender, visibility of the landmarks, and misalignment did not influence measurement accuracy. This parameter is the first tibia-related landmark for assessing the JL, which advantageously corresponds to the tibia-first technique in revision surgery.
  
  
  METHODS
  Diagnostic Study, Level II.
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, Regensburg, Germany. Guenther.Maderbacher@klinik.uni-regensburg.de.
authors.forename: Günther
authors.initials: G
authors.lastname: Maderbacher
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, Regensburg, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Keshmiri
authors.affiliation: Center of Clinical Studies, University of Regensburg, Regensburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Zeman
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, Regensburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.affiliation: Department of Orthopaedic Surgery, University of Regensburg, Regensburg, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Baier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011859:Radiography; D012086:Reoperation; D016474:Weight-Bearing
keywords: Contralateral knee; Fibular head; Joint line; Knee revision surgery