A Computer Navigation System Analysis of the Accuracy of the Extramedullary (Tibial) Alignment Technique in Total Knee Arthroplasty (TKA)

In total knee arthroplasty, mechanical alignment guides have improved the accuracy of implant alignment, but errors are not uncommon. In the present study, an image free computer assisted navigation system was used to analyse the accuracy of an extramedullary (tibial) alignment system, which is based on predetermined, fixed anatomical landmarks. Comparisons were made between two surgeons, with different levels of competency in order to determine if experience affected the accuracy of extramedullary tibial

Causative Factors for Femoral Pin Track Fractures in Navigated Total Knee Arthroplasty

This retrospective radiographic analysis of 57 patients (62 knees) examined two possible factors involved in pin tract fractures of the femur due to navigated total knee arthroplasty (TKA): the angle of the tracker pin with respect to the lateral femoral cortex, and the distance between the tracker pin and the lateral joint line. Our findings demonstrate a relationship between postoperative pin tract induced stress fractures (3 patients), with pin tract angles exceeding 15. Pin placement at a site more th

An Analysis of the Relationship between the Morphometry of the Distal Femur, and Total Knee Arthroplasty Implant Design

Current available implants for total knee replacement are based on the mormphometry of the Caucasian knee. We believe there are significant morphometric differences in the Asian knee that will be relevant in future implant designs. Sixty nine consecutive patients (80 knees) underwent computer navigated primary total knee arthroplasty. The anterior posterior (AP) length, and the medial lateral (ML) width of the distal femur, were analyzed, with respect to the final sizing details of four implants (femoral component) commonly used locally. The mean AP length was 59.9 (SD 4.8) mm, and the mean ML width was 65.0 (SD 5.0) mm. The overall mean aspect ratio (ML/AP) was 1.09 (SD 0.07). The mean aspect ratio for females was 1.08 (SD 0.07). Both were smaller than the aspect ratio of the implants which ranged from 1.11 to 1.13. All four implants tend to overhang at the medial lateral width of the distal femur. This is more obvious in females. Future implant designs should provide more ML wdth sizes for a given AP length, in addition to gender differences, for ths population.