If there is still pain three months after the ankle sprain, it is common for the following reasons: 1. Traumatic arthritis, serious damage to the cartilage of the joint surface after the ankle sprain, but the patient did not check the MRI of the ankle joint at the time of injury, so no cartilage damage was found. After normal weight-bearing, the cartilage damage will continue to aggravate and eventually cause traumatic arthritis, and the patient will have obvious joint pain when walking, even accompanied by joint swelling and activity limitation. 2. Chronic ankle instability, the ankle sprain tears the ligaments and decreases the stability of the ankle joint. If the patient is not found in time and does not brake for a long time, it will lead to incomplete repair of the ligaments and the patient will have instability of the ankle joint, and in the long run there will be pain, limitation of activity and recurrent effusion of the ankle joint.