title: [Influence of patellar position on tibial rotation after total knee arthroplasty].
abstract: OBJECTIVE
  Common total knee arthroplasty leads to resection of the anterior cruciate ligament. Lacking the ligamentous guidance, tibial rotation depends on different factors, i.e., muscle vectors. The present study measured the influence of the knee extensor mechanism determined by the mediolateral patella position on tibial rotation after implantation of two different knee prostheses.
  
  
  METHODS
  Physiologic tibial rotation and mediolateral patella translation were measured in ten fresh-frozen knee specimens. After implantation of the Interax- and Genesis II-prosthesis in each five of the ten specimens, kinematic measurements were made again with a determination of significant alterations.
  
  
  RESULTS
  The maximal medial patella position relative to the centre of the tibia was -6.6 mm (representing lateralisation); the maximal external tibial rotation was 4.1 degrees. After implantation of the Genesis II-prosthesis the external tibial rotation was reduced (p=0.03) with a relatively medialised patella (p=0.01), whereas after implantation of the Interax-prosthesis the external tibial rotation was increased (p=0.01) while the patella was measured to be lateralised similar to physiologic conditions.
  
  
  CONCLUSIONS
  The results of the current study revealed a potential influence of mediolateral patella position on tibial rotation following total knee arthroplasty, while both prosthesis systems were not able to reproduce physiologic joint kinematics.
authors.affiliation: Orthopädische Klinik der Medizinischen Hochschule Hannover (MHH), Anna-von-Borries-Str. 1-7, 30625 Hannover, Deutschland. sven.ostermeier@annastift.de
authors.forename: Sven
authors.initials: S
authors.lastname: Ostermeier
authors.forename: Carsten O
authors.initials: CO
authors.lastname: Tibesku
authors.forename: Adrian
authors.initials: A
authors.lastname: Skwara
authors.forename: Susanne
authors.initials: S
authors.lastname: Fuchs
authors.forename: Christina
authors.initials: C
authors.lastname: Stukenborg-Colsman
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D002102:Cadaver; D019544:Equipment Failure Analysis; D006801:Humans; D066298:In Vitro Techniques; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D008875:Middle Aged; D010329:Patella / Q000503:physiopathology*; D016059:Range of Motion, Articular; D012399:Rotation; D013977:Tibia / Q000503:physiopathology*; D016896:Treatment Outcome