Hip joint activity limitation may be hip joint fracture, hip joint dislocation, aseptic necrosis of femoral head, hip joint tuberculosis or ankylosing spondylitis. 1. Hip fracture: Hip fracture caused by trauma, such as acetabular fracture, femoral neck fracture, etc., can be caused by the fracture of the normal structure of the hip joint damage and hip joint activity limitation. Generally, X-ray and CT examination of the hip joint can assist in the diagnosis. 2. Hip dislocation: Hip dislocation caused by trauma, such as anterior hip dislocation, posterior hip dislocation, resulting in limited hip joint activities. X-ray examination of hip joint can assist in diagnosis. 3. Aseptic necrosis of femoral head: the early stage of femoral head necrosis usually does not affect the joint mobility, but the later stage will be caused by the femoral head collapse deformity, resulting in limited hip flexion and extension activities. X-ray examination of the hip joint can assist in the diagnosis. 4. Tuberculosis of hip joint: tuberculosis mycobacteria involve the hip joint and cause hip joint femoral head edge part or acetabular lesion, which affects the mobility, and the later stage will be due to cold abscess or pathologic subluxation resulting in limited joint activities. CT examination of the hip joint can assist in the diagnosis. 5. Ankylosing spondylitis: when ankylosing spondylitis involves the hip joint, it will cause limitation of hip flexion and extension activities, and in severe cases, it can cause ankylosing deformity of the joint. Sacroiliac joint or bilateral hip X-ray examination can assist in the diagnosis. When there is a limitation of hip joint activities, you should consult the hospital as soon as possible to clarify your condition, and according to the condition of the corresponding treatment, in order to restore the normal function of the hip joint activities.