The coronal alignment technique impacts deviation from native knee anatomy after total knee arthroplasty

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Total knee arthroplasty (TKA)

Background:

• Restoring native knee alignment is crucial in total knee arthroplasty (TKA).
• Different alignment techniques may alter pre-arthritic coronal phenotypes.
• Understanding these alterations is essential for surgical decision-making.

Purpose of the Study:

• To analyze and quantify changes in native coronal alignment in TKA patients.
• To compare the effectiveness of various alignment techniques in restoring pre-arthritic phenotypes.
• To define overall, femoral, and tibial coronal phenotypes.

Main Methods:

• Analysis of 520 TKAs using an image-free navigation system.
• Measurement of native knee angles (femorotibial, distal femur, proximal tibia).
• Simulation of five coronal alignment techniques: mechanical (MA), restricted mechanical (RMA), anatomical (AA), kinematic (KA), and restricted kinematic (RKA).

Main Results:

• Kinematic alignment (KA) restored the overall phenotype in 100% of cases, significantly outperforming other techniques (MA: 15%, RMA: 23%, AA: 2%, RKA: 79%).
• Similar high restoration rates were observed for femoral (KA: 100%) and tibial (KA: 100%) phenotypes.
• All techniques except KA induced significant changes in pre-arthritic anatomy.

Conclusions:

• Kinematic alignment (KA) is highly effective in restoring native coronal phenotypes during TKA.
• Other alignment techniques significantly alter the pre-arthritic anatomy.
• The clinical relevance of these anatomical alterations requires further investigation.