Abstract
The optimal overall lower extremity and component alignment in total knee arthroplasty (TKA) has recently been questioned, yet the majority of studies demonstrate TKA positioning to effect the rate of implant loosening, polyethylene stresses, knee kinematics, and gait. Most commonly, extramedullary tibial and intramedullary femoral alignment guides are used to set coronal alignment in TKA, but these “conventional” methods have a limited degree of accuracy. The goal of obtaining more precise and accurate component positioning has led to the development of computer-assisted surgical (CAS) techniques. Although numerous comparative studies have shown significant improvements with the use of CAS techniques, concerns over increased operative times, large capital costs, and the learning curve associated with their use have limited their widespread acceptance.
Recently, handheld navigation devices have been introduced with the goal of providing the accuracy of large-console CAS systems in an easy-to-use manner. These devices rely on accelerometer-based navigation to set cutting guide alignment relative to the mechanical axes of the femur and tibia. Unlike most CAS systems, handheld navigation systems avoid the use of additional pin sites and reference arrays in the femur and tibia, do not require a large computer with an infrared camera, and thus eliminate intraoperative line of site issues between the camera and tracking arrays. Several investigations have demonstrated handheld navigation devices to provide the same degree of alignment accuracy as large-console CAS systems, thus improving the ability of a surgeon to achieve their intraoperative targets for coronal alignment during TKA.
