A set of four axial CT scan slices of the hip joint illustrating different methods for measuring acetabular orientation and femoral head coverage. The images show a spherical femoral head articulating with the bony acetabulum. Each panel demonstrates a specific radiological measurement: (a) Acetabular Anteversion Angle (AAA), defined by the angle between the intercapital center line (ICL90) and the anteversion line (AVL) connecting the acetabular lips; (b) Femoral head coverage/roofing, determined by the ratio of the femoral head contained within the AVL to the total femoral diameter; (c) Posterior Acetabular Sector Angle (PASA), measured from the femoral head center to the posterior acetabular wall edge; and (d) Posterior Wall Angle (PWA), determined by the angle between the ICL90 and the tangent to the posterior articular surface. These measurements are used in orthopedic surgery to assess hip stability and the risk of dislocation following Bipolar Hemiarthroplasty (BHA). The imaging modality is clinical CT, focused on musculoskeletal diagnostic assessment.

This diagnostic image is an axial computed tomography (CT) scan of the human pelvis at the level of the acetabulum, demonstrating the radiographic measurement of acetabular anteversion (AA). The scan shows the bilateral hip joints, including the femoral heads and the surrounding acetabular walls. Overlaying the right acetabulum (anatomically the patient's right, left on the image), several reference lines are drawn: Line AB connects the anterior and posterior acetabular margins, representing the orientation of the acetabular opening. Lines C and D are vertical reference lines aligned with the sagittal plane of the pelvis. The acute angle formed between the acetabular line (AB) and the sagittal reference line (CD) is labeled 'AA', indicating the degree of acetabular anteversion. This measurement is clinically significant in orthopedic surgery and radiology for evaluating hip joint morphology, diagnosing impingement or dysplasia, and planning total hip arthroplasty to ensure stable component positioning.

This diagnostic image consists of two axial CT slices (labeled a and b) of the human hip joint at the level of the femoral head center, demonstrating standardized methods for assessing 3D acetabular morphology. Image 'a' illustrates the measurement of acetabular anteversion (AV) using two intersecting yellow lines at the acetabular margins. Image 'b' demonstrates the measurement of the anterior acetabular sector angle (AASA) and the posterior acetabular sector angle (PASA). These angles are defined by a horizontal reference line passing through the center of the femoral head and lines extending to the anterior and posterior acetabular rims, respectively. These measurements are clinically significant in orthopedics for evaluating bony coverage of the femoral head, diagnosing acetabular dysplasia, and planning or evaluating surgical interventions such as rotational acetabular osteotomy (RAO). The images provide a high-contrast view of cortical bone against surrounding soft tissue, essential for precise morphometric analysis of the acetabulum.