Analysis of lower extremity alignment (LEA) in children with recurrent patellar dislocation by EOS system

Area of Science:

• Orthopedics
• Biomechanical engineering
• Radiology

Background:

• Recurrent patellar dislocation (RPD) significantly impacts young, active individuals.
• Identifying lower limb alignment (LEA) abnormalities is crucial for understanding RPD.
• Previous studies suggest links between RPD and LEA issues like femoral anteversion and knee valgus.

Purpose of the Study:

• To utilize EOS imaging for detecting LEA anomalies associated with RPD.
• To enable three-dimensional assessment of LEA under load-bearing conditions.
• To identify specific LEA parameters that serve as risk factors for RPD.

Main Methods:

• Retrospective analysis of 100 limbs (50 RPD group, 50 control group).
• EOS technology (2D and 3D imaging) used for measurements in a standing position.
• Key parameters measured: Femoral neck shaft angle (NSA), Mechanical femoral tibial angle (MFTA), Mechanical lateral distal femoral angle (mLDFA), Medial proximal tibial angle (MPTA), Anatomical femoral anteversion (AFA), External tibial torsion (ETT), and Femorotibial rotation (FTR).

Main Results:

• Significant differences in NSA (3/2D), MFTA (3/2D), mLDFA (3D), MPTA (3D), AFA, and FTR between RPD and control groups.
• No significant difference in MPTA (2D) and ETT.
• Binary logistic regression identified mLDFA (3D), AFA, NSA (3D), and FTR as significant risk factors for RPD.

Conclusions:

• EOS imaging effectively identified abnormal LEA parameters as risk factors for RPD.
• Abnormalities in NSA, MFTA, mLDFA, MPTA, AFA, and FTR are associated with RPD.
• Children exhibiting these LEA risk factors require targeted knee joint protection.