title: Combining different rotational alignment axes with navigation may reduce the need for lateral retinacular release in total knee arthroplasty.
abstract: OBJECTIVE
  The aim of the study was to compare femoropatellar alignment and the incidence of lateral retinacular release (LRR) in total knee arthroplasty (TKA) in which the rotational alignment of the femoral component was determined using a combination of different rotational alignment axes and navigation or a single reference axis in the standard procedure.
  
  
  METHODS
  We assessed 66 patients undergoing TKA in whom the rotation of the femoral component was determined on the posterior condylar axis in standard procedures (group A) and 65 patients in whom it was determined by combining the posterior condylar axis, anteroposterior axis and epicondylar axis in navigated procedures (group B). The mean age was 68 and 69 years in groups A and B, respectively. Patellar tracking was assessed after deflation of the tourniquet and LRR performed in the presence of maltracking. Visual analogue scale (VAS), Knee Society Score (KSS), Lonner patellar score and patellar tilt were recorded.
  
  
  RESULTS
  LRR was carried out in 18 cases (27 %) in group A and in four (6 %) in group B (p = 0.003). The KSS and VAS were improved significantly compared to the preoperative status, but with no significant differences between the two groups. The patellar score showed a greater improvement in the navigated compared to the standard group at the four week follow-up. Patella tilt improved significantly in both groups. The complication rate was similar in the two groups.
  
  
  CONCLUSIONS
  Combining different rotational alignment axes with navigation significantly reduces patellar maltracking and the need for LRR compared to the standard procedure in which the posterior condylar axis is used as single anatomical reference.
authors.affiliation: Department of Anatomy, Histology, Medico Legal and Orthopaedic Science, University La Sapienza, Piazzale Aldo Moro, 5, 00185, Rome, Italy. md3581@mclink.it
authors.forename: Gianluca
authors.initials: G
authors.lastname: Cinotti
authors.forename: Francesca R
authors.initials: FR
authors.lastname: Ripani
authors.forename: Pasquale
authors.initials: P
authors.lastname: Sessa
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giannicola
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D017760:Bone Malalignment / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000033:anatomy & histology* / Q000502:physiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D017847:Patellar Ligament / Q000601:surgery; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D012399:Rotation; D025321:Surgery, Computer-Assisted / Q000379:methods*