title: Tibio-femoral and patello-femoral joint kinematics during navigated total knee arthroplasty with patellar resurfacing.
abstract: OBJECTIVE
  In total knee arthroplasty, surgical navigation systems provide tibio-femoral joint (TFJ) tracking for relevant bone preparation, disregarding the patello-femoral joint (PFJ). Therefore, the important intra-operative assessment of the effect of component positioning, including the patella, on the kinematics of these two joints is not available. The objective of this study is to explore in vivo whether accurate tracking of the patella can result in a more physiological TFJ and PFJ kinematics during surgery.
  
  
  METHODS
  Ten patients underwent navigated knee replacement with patellar resurfacing. A secondary system was used to track patellar motion and PFJ kinematics using a special tracker. Patellar resection plane position and orientation were recorded using an instrumented probe. During all surgical steps, PFJ kinematics was measured in addition to TFJ kinematics.
  
  
  RESULTS
  Abnormal PFJ motion patterns were observed pre-operatively at the impaired knee. Patellar resection plane orientation on sagittal and transverse planes of 3.9° ± 9.0° and 0.4° ± 4.1° was found. A good restoration of both TFJ and PFJ kinematics was observed in all replaced knees after resurfacing, in particular the rotations in the three anatomical planes and medio-lateral patellar translation.
  
  
  CONCLUSIONS
  Patella tracking results in nearly physiological TFJ and PFJ kinematics in navigated knee arthroplasty with resurfacing. The intra-operative availability also of PFJ kinematics can support the positioning not only of the patellar component in case of resurfacing, but also of femoral and tibial components.
authors.affiliation: Movement Analysis Laboratory and Functional - Clinical Evaluation of Prostheses, Centro di Ricerca Codivilla-Putti, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136, Bologna, Italy, belvedere@ior.it.
authors.forename: C
authors.initials: C
authors.lastname: Belvedere
authors.forename: A
authors.initials: A
authors.lastname: Ensini
authors.forename: A
authors.initials: A
authors.lastname: Leardini
authors.forename: V
authors.initials: V
authors.lastname: Dedda
authors.forename: A
authors.initials: A
authors.lastname: Feliciangeli
authors.forename: F
authors.initials: F
authors.lastname: Cenni
authors.forename: A
authors.initials: A
authors.lastname: Timoncini
authors.forename: P
authors.initials: P
authors.lastname: Barbadoro
authors.forename: S
authors.initials: S
authors.lastname: Giannini
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D007592:Joint Diseases / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000601:surgery; D057071:Patellofemoral Joint / Q000503:physiopathology* / Q000601:surgery; D016059:Range of Motion, Articular; D025321:Surgery, Computer-Assisted; D013977:Tibia / Q000503:physiopathology* / Q000601:surgery