Three Novel Radiological Indicators for Diagnosis of Adult Acetabular Dysplasia

Overview

Acetabular dysplasia often accompanies by acetabular bone hyperplasia and osteonecrosis of the femoral head. These pathological changes can alter the position of the center of the femoral head. Thus, measurement errors will be generated on the anteroposterior radiographs of the adult pelvis involving centre-edge angle, acetabular angle (Sharp angle), and acetabular head index, eventually resulting in the inaccurate diagnosis of acetabular dysplasia. Herein, the investigators describe the protocol to verify three novel X-ray indicators, including offshoring index (OFI), moving up index (MUI) and teardrop baseline offshoring index (TBOI) of the femoral head. All data will be expressed as relative ratios, as the investigators expect to make an accurate diagnosis through avoiding the generation of errors resulting from measurement angles.

Acetabular dysplasia is a developmental malformation of the hip joint where the acetabulum become shallow and cannot fully cover the femoral head and the centre of the hip joint moves outward, resulting in an increased risk for joint subluxation or dislocation. Current diagnosis of acetabular dysplasia mainly depends on the pelvic anteroposterior X-ray film to understand whether there is dislocation of the hip joint, whether the concentricity of the femoral head and acetabulum is consistent, and whether there is secondary osteoarthritis or other hip diseases, such as femoral head ischemic necrosis, hip joint tuberculosis, and rheumatoid arthritis. The commonly used measurement indicators include centre-edge (CE) angle, acetabular angle (Sharp angle), and acetabular head index (AHI). Moreover, some differences exist in the measurement results between male and female patients. Acetabular dysplasia often accompanies by acetabular bone hyperplasia and necrosis of the femoral head, which have a greater impact on radiographic measurements, especially when measured with angles. It is difficult to determine the radiological landmark for the lateral edge of the acetabular roof due to the existence of bone hyperplasia, which produces a great influence on the accuracy of the measurement of the centre-edge angle and Sharp angle.

Conditions