Predicting postoperative coronal alignment in medial unicompartmental knee arthroplasty using the arithmetic...

Area of Science:

• Orthopedic Surgery
• Biomechanical Analysis
• Arthroplasty Research

Background:

• Coronal alignment is crucial for medial unicompartmental knee arthroplasty (UKA) success.
• Understanding predictors of postoperative alignment is essential for optimal surgical outcomes.

Purpose of the Study:

• To investigate the correlation between the arithmetic hip-knee-ankle angle (aHKA) and the actual postoperative (postop) hip-knee-ankle (HKA) angle following medial UKA.
• To assess the predictive value of aHKA for postop coronal alignment.

Main Methods:

• Retrospective analysis of 242 patients (254 knees) undergoing medial UKA.
• Calculation of aHKA using MPTA - LDFA + 180°.
• Analysis of relationships between postop HKA, aHKA, MPTA, and LDFA, with patient stratification by postop HKA angle.

Main Results:

• A strong positive association was found between aHKA and postop HKA angle (R²=0.4595, P<0.05).
• Positive correlation with MPTA (R²=0.2072, P<0.05) and negative correlation with LDFA (R²=0.2448, P<0.05) were also observed.
• These correlations held true for both fixed-bearing and mobile-bearing UKA prostheses.

Conclusions:

• The arithmetic hip-knee-ankle angle (aHKA) is a significant predictor of postoperative coronal alignment in medial UKA.
• aHKA can be utilized to anticipate postop alignment, regardless of the specific UKA prosthesis type.
• The study supports the use of aHKA in pre-operative planning to optimize coronal alignment in medial UKA procedures.