title: Improved femoral component rotation in TKA using patient-specific instrumentation.
abstract: BACKGROUND
  Patient-specific instrumentation (PSI) was introduced in an attempt to reduce positional outliers of components in total knee arthroplasty (TKA). It was hypothesized that PSI could help with the positioning of femoral components in optimal rotational alignment.
  
  
  METHODS
  A magnetic resonance imaging (MRI) analysis of 94 patients following TKA was conducted. Of these, 46 operations were performed using PSI and 48 using conventional instrumentation. The rotation of the femoral components was determined in the MRI and deviations>3° were considered outliers. Data were analyzed for positional outliers, observer reliability, and a variance comparison between implant groups.
  
  
  RESULTS
  There was excellent inter- and intraobserver reliability with low standard deviations for the determination of femoral component rotation. There were significantly more outliers in the conventional (22.9%) group than in the PSI group (2.2%, p=0.003).
  
  
  CONCLUSIONS
  In this setup, PSI was effective in significantly reducing outliers of optimal rotational femoral component alignment during TKA.
authors.affiliation: Department of Orthopedics and Rheumatology, University Hospital Marburg, Germany.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Heyse
authors.affiliation: Sporthopaedicum Straubing, Bahnhofplatz 27, 94315 Straubing, Germany. Electronic address: carsten@tibesku.de.
authors.forename: Carsten O
authors.initials: CO
authors.lastname: Tibesku
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D015331:Cohort Studies; D017076:Computer-Aided Design; D005260:Female; D005269:Femur / Q000473:pathology / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000473:pathology / Q000601:surgery; D007720:Knee Prosthesis; D008279:Magnetic Resonance Imaging; D008297:Male; D011300:Preoperative Care; D017755:Prosthesis Fitting / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012399:Rotation; D013977:Tibia / Q000473:pathology / Q000601:surgery
keywords: Femoral rotation; Patient-matched instrumentation; Patient-specific instrumentation; Total knee arthroplasty