If your arm is not straight and bent inward, consider developmental deformity, traumatic fracture, elbow dislocation, local muscle contracture, elbow joint degeneration. 1. The arm does not straighten and bend inward, i.e. elbow inversion deformity, may be born with elbow inversion, or during the growth and development process, the growth of cartilage on the outer side of the elbow is faster than that on the inner side. 2. Traumatic supracondylar humerus fracture, dislocation of the elbow joint, especially in children, improper treatment will be left with elbow inversion deformity. Separation of the epiphysis of the distal humerus can cause the growth of the medial humeral condyle to slow down or stop, resulting in an inversion deformity of the elbow. 3. Prolonged arm pressure or keeping in a position, resulting in muscle spasm of the elbow, resulting in elbow inversion. 4. Degenerative diseases of the elbow joint, such as osteoarthritis of the elbow joint, can cause the elbow bone joint to show flexion and inward bending. It is recommended to actively consult a doctor for standardized treatment under the guidance of a physician if the arm is not straightened and bent inward.