Component Rotation in Well-Functioning, Gap Balanced Total Knee Arthroplasty Without Navigation

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Medical imaging

Background:

• Component malalignment in total knee arthroplasty (TKA) can lead to clinical failure.
• The gap balancing (GB) technique prioritizes soft-tissue balance over precise component alignment.
• Variations in component placement may occur with the GB technique.

Purpose of the Study:

• To assess the precision of component alignment in well-functioning GB TKAs performed without navigation.
• To investigate the relationship between native femoral version, tibial torsion, and TKA component positioning.

Main Methods:

• Computed tomography (CT) was used to evaluate 93 TKAs with a minimum 2-year follow-up.
• Component rotational alignment, femoral version, and tibial torsion were assessed.
• Standardized methods were employed for rotational alignment assessment.

Main Results:

• Most evaluated components were within the desired rotational range.
• No significant correlation was found between native femoral version and femoral component rotational alignment (r=0.007).
• A weak correlation was observed between native tibial torsion and tibial component alignment (r=0.24).

Conclusions:

• The gap balancing technique, even as a secondary objective, generally achieves acceptable component rotation in TKA.
• Native osseous rotational geometry does not appear to significantly influence TKA component alignment.