title: The influence of component alignment on patellar kinematics in total knee arthroplasty.
abstract: OBJECTIVE
  Postoperative anterior knee pain is one of the most frequent complications after total knee arthroplasty (TKA). Changes in patellar kinematics after TKA relative to the preoperative arthritic knee are not well understood. We compared the patellar kinematics preoperatively with the kinematics after ligament-balanced navigated TKA.
  
  
  METHODS
  We measured patellar tracking before and after ligament-balanced TKA in 40 consecutive patients using computer navigation. Furthermore, the influences of different femoral and tibial component alignment on patellar kinematics were analyzed using generalized linear models.
  
  
  RESULTS
  After TKA, the patellae shifted statistically significantly more laterally between 30° and 60°. The lateral tilt increased at 90° of flexion whereas the epicondylar distance decreased between 45° and 75° of flexion. Sagittal component alignment, but not rotational component alignment, had a significant influence on patellar kinematics.
  
  
  CONCLUSIONS
  There are major differences in patellar kinematics between the preoperative arthritic knee and the knee after TKA. Combined sagittal component alignment in particular appears to have a major effect on patellar kinematics. Surgeons should be especially aware of altering preoperative sagittal alignment until the possible clinical relevance has been investigated.
authors.affiliation: Department of Orthopaedic Surgery and.
authors.forename: Armin
authors.initials: A
authors.lastname: Keshmiri
authors.forename: Günther
authors.initials: G
authors.lastname: Maderbacher
authors.forename: Clemens
authors.initials: C
authors.lastname: Baier
authors.forename: Ernst
authors.initials: E
authors.lastname: Sendtner
authors.forename: Jens
authors.initials: J
authors.lastname: Schaumburger
authors.forename: Florian
authors.initials: F
authors.lastname: Zeman
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Hans R
authors.initials: HR
authors.lastname: Springorum
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena / Q000502:physiology; D017760:Bone Malalignment / Q000517:prevention & control*; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D010329:Patella / Q000502:physiology*; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome