The effect of tibial polyethylene insert design on range of motion: evaluation of in vivo knee kinematics by a computerized navigation system during total knee arthroplasty.

Computer-assisted navigation for total knee arthroplasty offers the unique opportunity to assess in vivo knee kinematics during surgery and implement changes whenever appropriate. Using a computerized navigation system, the effect of 2 tibial polyethylene insert designs on knee kinematics in general and knee range of motion (ROM) in particular was evaluated in 37 knee arthroplasties in 30 patients. The Scorpioflex tibial insert was found to provide a significant increase in mean extension, mean flexion, and overall ROM of the knee compared with the standard tibial insert (P<.005) without affecting knee ligamentous balance. Navigation is a very effective and useful tool for intraoperative assessment of knee kinematics and accurate recording of ROM. Based on the information obtained from the navigation software, the surgeon can implement changes in selection of the knee components with beneficial effects in knee kinematics in general and knee ROM in particular. This may, in turn, translate to better clinical outcome of the knee arthroplasty.