Early screening and treatment of DDH in China has been gradually realized. Due to its developmental nature, post-treatment review needs to continue until the process of growth cessation (12-14 years old), and one of the most common tests is a simple orthopantomogram of the pelvis. However, many times parents may be told that the film is not standard and that it is difficult to give an accurate assessment of the condition. A standard orthopantomogram can provide the doctor with more accurate information to determine the condition and decide if further treatment is needed or if new problems are identified. How is a standard orthopantomogram taken? A standard radiograph is taken with the patient in a supine position with the lower extremities internally rotated an average of 15° to counteract the anterior tilt of the femur, and with the x-ray tube perpendicular to the examination bed at a distance of 3000 px from the film. the crosshairs should be aligned with the midpoint of the line from the superior border of the pubic symphysis to the anterior superior iliac spine bilaterally. All parents need to know is how to position their child during the film. Since newborns have a 40° physiological flexion contracture of the hip joint, which disappears naturally with growth and development at 6 to 8 months of age. Therefore, it is important to cover the perineum, flex the hip about 30° (with a thin wooden block under the thigh), and straighten both lower limbs naturally with the patella facing upward (Figure 1). Older children can refer to the standard film, with the legs straight and together, knees and toes facing the sky, and the midline of the body through the middle of the legs, i.e., the entire body is kept straight (Figure 1). Figure 1: Correct filming posture Left: One person holds the child’s armpit to control twisting while one person holds both lower legs, pressing the thumbs on the patella to make sure the patella is facing upward, keeping the hips naturally lying flat and both lower limbs naturally straight, taking care not to press down hard to avoid causing the child’s hips to buckle. Right: The larger child lies naturally flat, with the toes exactly opposite each other when the patella is facing up. What kind of film is a standard orthopantomogram of the pelvis? Commonly used methods include: whether the tip of the tailbone is facing the pubic symphysis; whether the closed foramen and the iliac wing on both sides are symmetrical; and whether the distance from the tip of the tailbone to the upper edge of the pubic symphysis is within the normal range (generally 10-30 mm in adults, temporarily missing in children) (Figure 2). Figure 2. Standard pelvic orthopantomogram judgment structure