In vivo knee kinematics in total knee replacement as evaluated by a computerized navigation system -The effect of tibial polyethylene insert design on range of motion

摘要

Objectives: The purpose of this study was to evaluate the effect of various tibial polyethylene inserts designs on knee range of motion and kinematics as measured intra-operatively using a computerized navigation system. Background: Computer assisted (navigated) total knee replacement is thought to have the potential to improve component alignment and the eventual clinical outcome. The perceived advantages of navigation system include precise positioning of surgical jigs, accurate bone cuts, and improved component positioning and limb alignment. In addition, the system provides an instant feedback regarding in vivo kinematics of the joint. This ability of the navigation system provides unique opportunity to assess in vivo kinematics of the knee during surgery and implement beneficial changes. Methods: The Stryker~(TM) Knee Navigation system was used in this study. Extramedullary navigation jigs were positioned and the bone cuts performed based on the information obtained from the navigation system. Following implantation of the components, different designs of polyethylene inserts were introduced and the knee kinematics examined using the navigation software. In particular the range of motion and the soft tissue balance of the knee were evaluated. The maximum range of motion was recorded using a standardized gravity test. The knee prosthesis implante'd was the Scorpio~(TM) posterior stabilized system, and the tibial components tested were the standard posterior stabilized tibial insert and a modified tibial insert designed to increase knee flexion (Scorpioflex~(TM))