A Small Step to Improve Tibial Alignment in Knee Replacement

Introduction: Though total Knee replacement has proved to be a rewarding surgery for patients with end stage knee arthritis, errors in surgical technique leading to malalignment of components can lead to early failure. The aim of this study was to increase the accuracy in identifying the centre of ankle joint which is the first step in achieving a proper tibial cut for a well placed tibial implant. Technique: We propose a simple, reproducible technique to locate centre of ankle under image intensifier. Results: The above technique was used in 30 patients who were operated by two surgeons during a period of 6 months from January 2022 to June 2022. Post-op measurements of the alignment of tibial implant were done electronically on computer and physically on X-rays. 21 of the 30 cases (70%) had good placement of the implant within 1 degree of ideal alignment and 9 (30%) within 2 degrees. Discussion: A correct proximal tibia cut for a well aligned tibial component is achieved with the help of precise application of the cutting jigs. Extramedulalry jigs used to make the proximal tibia cut have to be aligned parallel to the axis of the tibia and centred over the midpoint of talus. Several methods have been proposed by various authors to locate centre of the ankle joint. However, at present there is no consensus on the best method. Even computer navigation relies on accurate feeding of anatomical reference points which is done manually. Conclusion: Our technique is precise, accurate, repeatable, objective and less time consuming. It adds value to achieving the final aim of a good implant position. The technique has a dual advantage as it gives a better estimate of not only the centre of the ankle but also the centre of the distal tibial mechanical axis.