Patellar tracking in total knee arthroplasty: Inset versus onset design

Kace A. Ezzet, Allen L. Hershey, Darryl D. D'Lima, Steve E. Irby, Kenton R. Kaufman, Clifford W. Colwell

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Patellar components come in onset and inset designs. Kinematic differences between these designs were studied in a cadaver model of closed kinetic chain knee extension. Seven frozen knees were implanted with a standard posterior cruciate-retaining design. Each knee first was tested with the inset design, followed by the onset design in the Oxford Knee Rig. Three-dimensional tracking of the femur, tibia, and patella was performed using an electromagnetic system during active knee extension under load. No statistically significant differences were seen in knee kinematics between the 2 designs. The inset patella tended to shift laterally and tilt laterally more than the onset patella. This difference may be clinically significant.

Original languageEnglish (US)
Pages (from-to)838-843
Number of pages6
JournalJournal of Arthroplasty
Issue number7
StatePublished - Jan 1 2001


  • Inset patella
  • Kinematics
  • Onset patella
  • Patellar design
  • Patellar tracking
  • Total knee arthroplasty

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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