Sensor technology in total knee arthroplasty

Abstract

Total knee replacement surgery is highly successful in terms of component survival. However, approximately 20% of patients report dissatisfaction with their outcome. It is speculated that many of these patients may have soft tissue imbalance or mal-tracking components which can lead to stiffness or subtle instability. Surgeons currently rely on subjective feel and visual estimation to determine if the total knee has proper soft tissue balance. Surgical experience and case volume play a major role in each surgeon’s relative skill in balancing the knee properly. Sensor technology incorporates embedded microelectronics in a trial tibial insert. While the surgeons perform a passive range of motion with trial components in place, quantified pounds of pressure and tracking patterns in the medial and lateral compartments are demonstrated on a graphical interface. The surgeon can decide whether to accept the knee balance, perform a soft tissue release, or redo a bone cut. If soft tissue balancing is performed, the surgeon can visualize changes in compartment pressures on the graphical interface as sequential soft tissue releases are performed with a pie-crusting method. Minimal bone recuts are being used more frequently. A multicenter evaluation utilizing sensor technology has demonstrated significantly improved outcomes when the compartment pressures were within 15 lb of each other.