Tibialis Anterior Tendon: A Reliable Anatomical Landmark Indicating the Ankle Centre. Potential Utility in Extra-Medullary Alignment During Total Knee Replacement

Background: Extramedullary alignment is a well established surgical technique during total knee replacement. There are different methods to achieve accuracy but variability is quite extensive. To attain uniformity in the surgical technique we have been using the tibialis tendon to align our resection guide. This may prove to be a useful aid for surgeons during knee replacement surgery. Objectives: The purpose of our study was to establish if tibialis anterior tendon represents the centre of ankle joint and if it could be used as an anatomical reference for alignment during knee replacement. Methods: We designed a retrospective radiological cohort study. We studied sixty MRI scans of normal ankles. The centre of ankle joint was marked as a bisection point of the intermalleolar line at the level of superior surface of the talus. A line was drawn connecting the centre of Achilles tendon to the ankle centre and this was extended anteriorly. This line was found to have a constant relation to the ankle centre and it would simulate the positioning of the standard alignment device used. Results: The tibialis anterior tendon lies less than 3mm medial to the ankle centre in the frontal plane. Conclusions: We conclude that the tibialis anterior tendon can be used during knee replacement surgery as an accurate alignment guide.