title: The impact of joint line restoration on functional results after hinged knee prosthesis.
abstract: BACKGROUND
  Hinged knee prosthesis is an effective treatment method as a salvage procedure in marked ligamentous insufficiency and severe bone defects. Joint line determination and restoration are difficult due to large bone defects and distorted anatomy. We evaluated the impact of joint line alteration on the outcome in rotating hinge knee arthroplasty (RHKA).
  
  
  METHODS
  35 patients who had rotating hinged knee prosthesis applied between 2008 and 2013 were evaluated in this retrospective study. The patients were studied radiologically and clinically. Five patients were lost to followup and two patients died, leaving a total of 28 (7 male, 21 female) patients for final evaluation. The average age of the patients was 66.19 ± 8.35 years (range 52-83 years). The patients were evaluated clinically with Knee Society knee and functional score and patellar score. The joint line positions were evaluated radiographically with femoral epicondylar ratio method. The outcomes were also evaluated according to age, body weight and gender. Student's t-test, independent t-test, and the Wilcoxon signed rank test were used in the statistical analysis.
  
  
  RESULTS
  The mean Knee Society knee and functional score significantly improved from preoperative 19.52 ± 11.77 and 12.5 ± 15.66 respectively to 72.46 ± 14.01 and 70.36 ± 9.22 respectively postoperatively (P < 0.001). The mean range of motion of the knee improved from 55.95° ± 25.08° preoperatively to 92.14° ± 13.47° postoperatively (P < 0.001). Joint line position was restored in 20 patients (71.4%). Joint line alteration did not affect Knee Society Scores (KSSs) in contrast to patellar scores. Additionally, KSS was better in the patients with body mass index ≤30 at followup (P = 0.022 and P = 0.045).
  
  
  CONCLUSIONS
  RHKA is an effective salvage procedure for serious instability and large bone defects. Restoration of the joint line improves the patellar score although it had no effect on the clinical outcome.
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Numune Training and Research Hospital, Ankara, Turkey.
authors.forename: Serdar
authors.initials: S
authors.lastname: Yilmaz
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Numune Training and Research Hospital, Ankara, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Cankaya
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Numune Training and Research Hospital, Ankara, Turkey.
authors.forename: Alper
authors.initials: A
authors.lastname: Deveci
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Ataturk Training and Research Hospital, Ankara, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Firat
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Numune Training and Research Hospital, Ankara, Turkey.
authors.forename: Bulent
authors.initials: B
authors.lastname: Ozkurt
authors.affiliation: Department of Orthopaedics and Traumatology, Ankara Ataturk Training and Research Hospital, Ankara, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Bozkurt
keywords: Arthroplasty; Knee replacement; epicondyle; joint line; knee; knee prosthesis; osteoarthritis; total