Thin, shortened and ulnarly inclined forearm, dislocation of the radial head, and limited rotational function of the forearm are among the clinical symptoms of congenital ulnar agenesis disease. The cause is due to inhibition of the growth of the second, third and fourth rays in addition to the main stem in the embryonic limb bud. Complete ulnar agenesis is very rare, while partial agenesis is more common. So what tests are available for this disease? X-rays X-rays are the preferred test for initial screening of the disease X-rays are inexpensive and suitable for routine examination in most patients, especially for initial screening of the disease. It has good diagnostic value for diseases such as fracture displacement, bone diseases with bone changes, bony lesions in joint areas, opaque foreign body retention, organic heart and lung diseases, and digestive system obstruction. In addition, radiographs can detect diseases in which the patient feels discomfort only when changing position. Especially power position film examination, there are still very few MRI can replace X-ray examination in China. CT examination CT can show vascular lesions CT examination is significantly better than X-ray in showing cross-section, especially for high-density tissues with clear image, and for measuring the distance between bony structures with high accuracy, and the scanning time is significantly shorter than MRI, generally only a few minutes. CT can clearly show the direction of blood vessels and vascular lesions, and the inspection sensitivity for tumors is significantly higher than that of ordinary X-ray. Moreover, multi-row spiral CT can perform three-dimensional imaging, which helps to display tissue and organ lesions in three dimensions. However, CT scan is limited by the different professional level of technicians and the limitation of scanning level interval, so it cannot read the information of the examination site as a whole, which leads to a certain rate of missing diagnosis. In addition, the radiation dose of CT is much higher than that of X-ray, and the clarity and resolution of soft tissue imaging is not high. MRI (magnetic resonance imaging) MRI is better for soft tissue examination MRI (magnetic resonance imaging) is the most different from X-ray and CT examination because there is no X-ray radiation during the examination, and the damage to the body is minimal. It is mainly used to detect soft tissue diseases, and in orthopedics it is mainly used to detect disc lesions, spinal cord lesions, meniscal lesions, inflammatory lesions and hemorrhagic lesions. MRI has a high sensitivity for vascular diseases. However, MRI also has disadvantages: first, the cost of general MRI examination is relatively expensive; second, the examination time for each part is long, generally tens of minutes; third, the imaging accuracy of some bone tissues is not as accurate as CT; and the cost of dynamic MRI is several 10 times more than dynamic X-ray film.