Native acetabular version: 3D CT analysis 
of the psoas valley

Area of Science:

• Orthopedic Surgery
• Radiology
• Biomedical Engineering

Background:

• Acetabular version is crucial for hip joint function and implant success.
• Psoas tendon impingement is a known complication, potentially related to acetabular anatomy.
• The anatomical significance of the psoas valley for native version measurement is not well understood.

Purpose of the Study:

• To assess the anatomical significance of the psoas valley for measuring native acetabular version.
• To compare a novel psoas valley-based method with a traditional acetabular rim reference method using 3D CT.
• To evaluate the reproducibility and reliability of the new measurement technique.

Main Methods:

• Utilized 65 high-resolution 3D CT scans of non-diseased hips.
• Measured native acetabular version angles using the psoas valley landmark.
• Compared measurements with a reference method utilizing the full acetabular rim (320°).
• Assessed intra-observer and inter-observer reliability and Bland-Altman limits of agreement.

Main Results:

• The psoas valley method demonstrated high reproducibility and reliability.
• Both methods yielded similar acetabular version measurements across a wide range (males: 5°-35°, females: 10°-40°).
• No statistically significant gender differences were observed in version measurements (p = 0.3670).
• Bland-Altman analysis showed narrow limits of agreement (+4.6° to -4.3°).

Conclusions:

• The psoas valley is a significant anatomical landmark for assessing native acetabular version.
• The novel psoas valley method using 3D CT is reliable and reproducible.
• This technique offers a valuable addition to understanding native hip bony anatomy and assessing version.