Intramedullary versus extramedullary alignment of the tibial component in the Triathlon knee

Background: Long term survivorship in total knee arthroplasty is significantly dependant on prosthesis alignment. Our aim was determine which alignment guide was more accurate in positioning of the tibial component in total knee arthroplasty. We also aimed to assess whether there was any difference in short term patient outcome. Method: A comparison of intramedullary versus extramedullary alignment jig was performed. Radiological alignment of tibial components and patient outcomes of 103 Triathlon total knee arthroplasties were analysed. Results: Use of the intramedullary was found to be significantly more accurate in determining coronal alignment (p = 0.02) while use of the extramedullary jig was found to give more accurate results in sagittal alignment (p = 0.04). There was no significant difference in WOMAC or SF-36 at six months. Conclusion: Use of an intramedullary jig is preferable for positioning of the tibial component using this knee system.