The popliteal surface axis may define hip anteversion.

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Radiology

Background:

• Accurate measurement of femoral anteversion is crucial in orthopedic procedures and biomechanical analysis.
• Existing computed tomography (CT)-derived methods, such as the trans-epicondylar axis (TEA) and posterior condylar axis (PCA), serve as gold standards but may have limitations.
• A novel reference axis is proposed to enhance the reliability and reproducibility of anteversion measurements in three-dimensional (3D) modeling.

Purpose of the Study:

• To evaluate the usability and reliability of a new popliteal surface axis (PSA) for three-dimensional (3D) femoral modeling.
• To determine if the PSA is a reproducible method for measuring anteversion.
• To assess the correlation of PSA-derived anteversion measurements with established CT-derived standards (TEA and PCA).

Main Methods:

• Three-dimensional solid models were generated from the left femoral CT data of 100 participants (50 males, 50 females).
• The newly proposed popliteal surface axis (PSA) was utilized for anteversion measurement.
• Measurements derived from PSA were compared against those obtained using the trans-epicondylar axis (TEA) and posterior condylar axis (PCA).

Main Results:

• The popliteal surface axis (PSA) demonstrated high reproducibility, measurable in 99% of the sample.
• Mean anteversion measurements were (-) 1.8° for PSA, 10.7° for PCA, and 4.4° for TEA.
• PSA showed a perfect correlation with both PCA and TEA for anteversion measurements (p<0.001, r=0.92).

Conclusions:

• The newly defined popliteal surface axis (PSA) is a reproducible and reliable reference axis for femoral anteversion measurement.
• PSA can be effectively used in three-dimensional (3D) modeling derived from CT scans.
• The PSA presents a viable alternative method for determining femoral anteversion, correlating well with established standards.