Abstract
Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment can affect clinical results. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissue, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening.
A handheld, accerelerometer based navigation unit for use in total knee replacement has recently become available to assist the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment.
Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results.
The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA.
