Introduction
Individualized component positioning is becoming a growing trend in knee arthroplasty. Rotation of the tibial component is particularly problematic due to the absence of a reliable anatomical marker. In clinical practice, the tibial component rotation is usually determined by a line connecting the center of the posterior cruciate ligament insertion and the medial third of the tibial tubercle. A correlation between rotation of the distal femur and lower extremity angle in the frontal plane has already been proven. A similar relationship could be expected for the rotation of the proximal tibia. The main aim of this study was to analyze the relationship between frontal plane lower limb angles and tibial tubercle rotation.
Methods
This prospective study included patients scheduled for total knee arthroplasty. Prior to surgery, patients underwent a computed tomography scan of the lower limbs. Key anatomical points were selected manually and the remaining axes and angles were then calculated with programming scripts.
Results
A statistically significant correlation was found between the medial proximal tibial angle and tibial tubercle rotation in 199 knees. Greater tibial varus was associated with increased external rotation of the tibial tubercle.
Discussion and conclusion
In knees with greater tibial varus, the tibial tubercle is a less reliable marker for determining tibial component rotation. A more internally rotated tibial component may be advisable in such cases in order to preserve proper rotational alignment between the implant components.
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