Tibial component rotation alters soft tissue balance in a cruciate retaining total knee arthroplasty

Abstract

Our aim was to understand whether using different landmarks for tibial component rotation influenced articular contact pressures in a balanced total knee arthroplasty (TKA). Twelve patients underwent TKA (Triathlon CR, Stryker Inc., Mahwah, NJ) and contact pressures were assessed using a wireless sensor. Robotic arm assisted TKA using a functional alignment technique was performed, with balanced gaps between medial and lateral compartments. Compartment pressures were measured with the trial tibial component rotated to Akagi's line and to Insall's axis respectively. Rotating the tibial component to Akagi's line resulted in a significantly greater proportion of knees being balanced and lower contact pressures than when the tibial component was rotated to Insall's axis at 10°, 45° and 90° of flexion (p < 0.05). Medial compartment pressures were significantly increased in 10° of flexion, as were lateral compartment pressures in all positions when the tibial component was aligned to Insall's axis (p < 0.05). The mean difference in rotation observed with the two landmarks was 6.9° (range 4.1–9.1°). Rotational alignment of the tibial component using Akagi's line reduced contact pressures, improved balance and reduced the need for soft tissue release when compared with Insall's axis in robotic arm assisted TKA.

Keywords:

• Tibial rotation
• total knee arthroplasty balance
• sensor balance
• robotic assisted total knee arthroplasty

Acknowledgements

Bethany Tippett – data collection.

Christina Esposito – manuscript editing and proof reading.

Disclosure statement

In accordance with Taylor & Francis policy and my ethical obligation as a researcher, I(GC) am reporting that I am a consultant to Stryker Orthopedics, a company that may be affected by the research reported in the enclosed paper. I have disclosed those interests fully to Taylor & Francis, and I have in place an approved plan for managing any potential conflicts arising from [that involvement]. No other authors have conflicts of interest to declare. The data that support the findings of this study are available from the corresponding author, [GC], upon reasonable request.