title: Proprioception after bicruciate-retaining total knee arthroplasty is comparable to unicompartmental knee arthroplasty.
abstract: OBJECTIVE
  Rising expectations in functional performance of total knee joints are inciting further improvement of knee arthroplasty implants. From a patient-centred view, bicruciate-retaining models provide a more natural feeling knee. However, there is no evidence of functional advantage for these implants. The aim of this study was to evaluate balance ability as a measure of proprioception in patients with a bicruciate-retaining total knee arthroplasty.
  
  
  METHODS
  A prospective, controlled trial was conducted to compare balance ability in 60 patients after arthroplasty of the knee for osteoarthritis. We compared patients with a bicruciate-retaining knee arthroplasty (BCR group) to a control group of patients with a medial unicompartmental knee arthroplasty (UKA group) and another control group of patients with a posterior stabilized total knee arthroplasty (PS group). The patient population comprised 30 women (50.0 %) and 30 men in three cohorts of 20 each. The mean age was 62.1 ± 8.0 years (range 43-78). Patients were evaluated preoperatively and 9 months post-operatively. The evaluation included clinical, radiological, and balance testing-a single-leg stance with eyes closed compared to eyes open. The difference in area of sway between eyes closed and eyes open represents static balance ability after knee arthroplasty.
  
  
  RESULTS
  Perioperative data showed that there was no intra-operative fracture of the intercondylar eminence. There was a decreased post-operative knee extension 9 months post-operative in the BCR group, which was not clinically relevant in any case. We recorded a lower difference in the area of sway between eyes closed and eyes open (ΔA(ec-eo)) for the BCR group (p = 0.01) and the UKA group (p = 0.04) compared to the PS group.
  
  
  CONCLUSIONS
  This study found superior static balance ability after preservation of both cruciate ligaments in arthroplasty of the knee, indicating superior proprioceptive function. Hence, BCR implants could provide improved functional properties. Superior proprioceptive function of bicruciate-retaining implants can be an important factor in implant selection. Further prospective, randomized studies to investigate kinematics and long-term survivorship of bicruciate-retaining implants are needed.
  
  
  METHODS
  II.
authors.affiliation: Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany. florian.baumann@ukr.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Baumann
authors.affiliation: Sporthopaedicum Regensburg, Hildegard-vn-Bingen-Str. 1, 93053, Regensburg, Germany.
authors.forename: Özkan
authors.initials: Ö
authors.lastname: Bahadin
authors.affiliation: Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Krutsch
authors.affiliation: Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Zellner
authors.affiliation: Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nerlich
authors.affiliation: Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany.|Sporthopaedicum Regensburg, Hildegard-vn-Bingen-Str. 1, 93053, Regensburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Angele
authors.affiliation: Sporthopaedicum Straubing, Bahnhofsplatz 27, 94315, Straubing, Germany.
authors.forename: Carsten Oliver
authors.initials: CO
authors.lastname: Tibesku
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008023:Ligaments, Articular / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000523:psychology / Q000601:surgery*; D004856:Postural Balance; D011434:Proprioception; D011446:Prospective Studies; D011474:Prosthesis Design; D016059:Range of Motion, Articular
keywords: Bicruciate-retaining total knee arthroplasty (BCR-TKA); Outcome; Proprioception; Unicompartmental knee arthroplasty (UKA)