title: A useful radiologic method for preoperative joint-line determination in revision total knee arthroplasty.
abstract: Intraoperative joint-line determination during revision TKA is difficult and no method exists to plan the position preoperatively. Two questions need to be answered: to which extent does the joint line differ from its anatomic position after revision TKA if it has only been determined intraoperatively, and can the joint line be calculated preoperatively based on the transepicondylar width. Of 22 consecutive patients with complete preoperative (before and after primary TKA) and postoperative (after revision TKA) radiograph documentation, the joint-line position was measured on plane radiographs using the medial epicondyle as a reference. On another set of 45 consecutive patients with no knee disorders other than meniscal lesions, the transepicondylar axis width (TEAW) and the perpendicular distance from the medial and lateral epicondyles to the joint line were measured twice by two independent observers on plane AP radiographs of the knee. Significant joint-line alterations were observed after primary and revision TKA, implicating that a method for preoperative planning is needed. Because a linear correlation between the TEAW and the perpendicular distance from the epicondyles to the joint-line tangent was found, the ratio is useful to calculate the true joint-line position from the TEAW before revision TKA.
  
  
  METHODS
  Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, University of Zurich, Balgrist, Switzerland. jose.romero@endoclinic.ch
authors.forename: Jose
authors.initials: J
authors.lastname: Romero
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Seifert
authors.forename: Olaf
authors.initials: O
authors.lastname: Reinhardt
authors.forename: Oliver
authors.initials: O
authors.lastname: Ziegler
authors.forename: Oliver
authors.initials: O
authors.lastname: Kessler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001175:Arthrography / Q000379:methods*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007432:Intraoperative Period; D007592:Joint Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011475:Prosthesis Failure; D012086:Reoperation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging* / Q000601:surgery; D055815:Young Adult