The coronal plane alignment of the knee classification does not correlate with the functional knee phenotype...

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Medical imaging

Background:

• Lower limb coronal anatomy exhibits significant variability in both healthy individuals and those undergoing total knee arthroplasty (TKA).
• Two distinct classifications, functional knee phenotypes and coronal plane alignment of the knee (CPAK), have been proposed but not directly compared.
• Understanding coronal alignment is crucial for successful TKA outcomes.

Purpose of the Study:

• To compare the hip-knee-ankle angle (HKA) and arithmetic hip-knee-ankle angle (aHKA) measurements in the same patient during TKA.
• To investigate the relationship between these two measures and their correlation with CPAK classification.

Main Methods:

• A retrospective analysis of 520 TKA cases utilizing navigation assistance.
• Collection of anatomical parameters via a navigation system during surgery.
• Calculation of CPAK classification data and comparison of measured HKA and calculated aHKA values.

Main Results:

• The mean measured HKA was 3.0° varus (SD 6.0°), while the mean calculated aHKA was 1.8° varus (SD 4.8°).
• A statistically significant difference (p=0.005) was found between HKA and aHKA measurements in the same patient.
• A weak negative correlation was observed between HKA and aHKA values, with no relationship to joint line obliquity or CPAK class.

Conclusions:

• Significant differences and only partial correlation exist between HKA and aHKA measurements.
• These techniques provide complementary, rather than exclusive, information regarding coronal knee alignment.
• The clinical significance of these findings in TKA remains to be determined.