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Updated: Sep 14, 2025
Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty
Published on: February 27, 2018
Femoral components are positioned in greater external rotation using functional alignment in robot-assisted total
Anne Ruth van Meijeren1, Danielle Langeloo1, Hans-Peter van Jonbergen1
1Department of Orthopedic Surgery Deventer Hospital Deventer The Netherlands.
Purpose:
Objective of this study was to evaluate the effect of functional alignment on femoral component rotation compared to mechanical alignment in knees with a constitutional tibial varus alignment classified as coronal plane alignment of the knee (CPAK) types I, II and IV.
Methods:
This retrospective study included patients undergoing conventional total knee replacement (TKR) (n = 64) and robot-assisted TKR (n = 84). Coronal and axial measurements were performed manually and automatically using pre- and postoperative computed tomography images in the conventional group and robot-assisted group respectively.
Results:
Femoral component rotation was statistically significant more external rotated in the conventional group versus robot-assisted group (1.3° ± 2.7° vs. 0.76° ± 1.4°, p < 0.001). Also, the tibial plateau was placed statistically significant more in varus in the robot-assisted group compared to the conventional group (87.6° ± 2.5° vs. 88.9° ± 1.4°, p < 0.001).
Conclusion:
Functional alignment leads to more varus of the tibial component and less external rotation of the femoral component compared to mechanical alignment in TKR in patients with a constitutional tibial varus alignment. Since this is a radiological analysis, further research is needed to understand how these differences affect clinical outcomes as faster recovery, adequate patellar tracking and longer survival.
Level Of Evidence:
Level III.
