Surgical Alignment Techniques Comparisons for External Peak Knee Adduction Moments During Stair Descent

Description

This presentation focuses on a study that evaluates two surgical alignment techniques in total knee arthroplasty: mechanical alignment and kinematic alignment. Funded by Medacta International, the study aims to assess the functional outcomes of these techniques through a stair descent assessment among participants aged 18 to 80 years, who had undergone unilateral cruciate retaining total knee arthroplasty at least a year prior.



The mechanical alignment technique aims to align the hip, knee, and ankle linearly within a defined threshold of 0 ± 3 degrees of the mechanical axis. In contrast, kinematic alignment is tailored to individual patient anatomy which may fall outside the specified mechanical axis, potentially leading to unknown biomechanical implications.



Data collection included a series of trials monitored via a markerless motion capture system, examining key metrics such as knee abduction moments, peak and mean knee deduction moments, and analysis of Center of Mass (CAM) impulse through Matlab statistical analysis.



Results illustrated that the kinematic alignment group demonstrated significantly higher peak knee deduction moments compared to the mechanical alignment group during the initial phase of stance, with a similar observation noted for mean moments. Notably, there were no significant differences found in impulse values between the two groups.



The findings suggest that while kinematic alignment provides certain advantages in knee motion parameters post-surgery, it may also indicate a risk of uneven loading distribution in the medial compartment of the knee. Further investigation into trunk lean and joint line differences between the groups revealed potential explanatory factors for the observed discrepancies in loading patterns, highlighting the complex biomechanical implications of surgical alignment techniques. Future recommendations include refining assessments of handrail usage during stair descent to better understand its impact on results.

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