Figure 1. Mature hip: key eponymous pelvic lines, angles and landmarks. Drag the marker to reveal labels. Köhler line (KL) follows the ilioischial contour and provides a reference for medial acetabular depth and protrusio. The Sharp angle (SA) is formed between the horizontal inter-teardrop reference and a line from the inferior teardrop to the lateral acetabular roof, measuring acetabular inclination. The Köhler teardrop (TD) is the characteristic U-shaped summation shadow medial to the acetabulum. The centre-edge angle of Wiberg is formed at the femoral-head centre (C) between the vertical reference (CB) and a line extending to the lateral acetabular roof (CE), measuring lateral femoral-head coverage.
