Native non-osteoarthritic knees have a highly variable coronal alignment: a systematic review.

Area of Science:

• Orthopedics and Biomechanics
• Radiology and Imaging

Background:

• Coronal knee alignment is critical for joint health and is defined by hip-knee-ankle angle (HKA), femoral mechanical angle (FMA), tibial mechanical angle (TMA), and joint line convergence angle (JLCA).
• Current understanding of the natural variability in coronal knee alignment in non-osteoarthritic knees is limited.

Purpose of the Study:

• To systematically review existing literature on the variability of native coronal knee alignment parameters (HKA, FMA, TMA, JLCA) in non-osteoarthritic knees.
• To establish a baseline understanding of normal knee alignment variations.

Main Methods:

• A systematic literature search was conducted across MEDLINE, EMBASE, and Google Scholar up to November 1, 2018.
• Studies were included if they reported coronal alignment measurements in native, non-osteoarthritic knees, adhering to PRISMA guidelines.
• Data was extracted from 15 studies, with most utilizing weight-bearing long-leg radiographs (LLR).

Main Results:

• Mean hip-knee-ankle angle (HKA) ranged from 176.7° (males) to 180.7° (females).
• Mean femoral mechanical angle (FMA) varied from 92.08° (females) to 97.2° (females).
• Mean tibial mechanical angle (TMA) ranged from 84.6° (females) to 89.6° (females), and mean joint line convergence angle (JLCA) ranged from -0.47° (males) to -1.9° (females).

Conclusions:

• Significant variability exists across all measured coronal alignment parameters in non-osteoarthritic knees.
• This wide range underscores the need for individualized and anatomic approaches in knee replacement surgery.
• Understanding native knee alignment variability provides a foundation for studying changes in osteoarthritic knees.