Reliability of two-dimensional computed tomography for measuring hip anatomy

Area of Science:

• Radiology
• Orthopaedic Imaging
• Anatomy

Background:

• Accurate hip anatomy measurement is crucial for diagnosing conditions and conducting population studies.
• Two-dimensional pelvic computed tomography (CT) is a common imaging modality.
• Assessing the reliability of specific anatomical measurements is essential for consistent clinical application.

Purpose of the Study:

• To evaluate the inter- and intra-observer reliability of four hip anatomical measurements using 2D pelvic CT.
• To determine the consistency of measurements for the centre-edge angle of Wiberg, Sharp angle, acetabular depth ratio of Murray, and acetabular anteversion angle.

Main Methods:

• Three observers measured four hip angles on 2D pelvic CT scans from 20 adult patients.
• Measurements were repeated after a 6-week interval to assess intra-observer variability.
• Intraclass correlation coefficients (ICCs) were calculated to quantify reliability, categorized as poor, fair, moderate, substantial, or excellent.

Main Results:

• Substantial reliability was found for the Sharp angle (ICC=0.74), acetabular anteversion angle (ICC=0.69), and acetabular depth ratio of Murray (ICC=0.62).
• Fair reliability was observed for the centre-edge angle of Wiberg (ICC=0.40).
• Inter- and intra-observer variability were assessed for all measurements.

Conclusions:

• The Sharp angle, acetabular anteversion angle, and acetabular depth ratio of Murray demonstrate reliable measurement using 2D pelvic CT.
• These specific measurements are deemed appropriate for use in population-based studies of hip anatomy.
• The centre-edge angle of Wiberg showed lower reliability in this study.