A small buttock after femoral neck surgery may be caused by uneven fat distribution, local swelling, muscle atrophy and other factors. 1. Uneven fat distribution: congenital uneven distribution of fat in the buttocks may result in a small buttock. This is a normal phenomenon and will not adversely affect the body, so there is no need to worry too much. 2. Local swelling: after femoral neck surgery, if the local swelling on the affected side has not completely subsided, there may be a small buttock after femoral neck surgery. Usually, after a period of recovery, the local swelling can be gradually relieved, and the situation of having a small buttock can be improved. 3. Muscle atrophy: after femoral neck surgery, not actively take the lower limb rehabilitation training, may lead to local muscle atrophy, the emergence of femoral neck surgery buttocks a small situation. There are many reasons for patients to have a small buttocks after femoral neck surgery, it is recommended that patients go to the hospital in time to carry out relevant examinations, so as to identify the cause of the disease.