Ankle arthritis can be caused by trauma. A sprain that never completely heals properly can cause significant ankle instability and foot malalignment. Over time, this type of imbalance can lead to excessive joint wear and tear. Painful, debilitating post-traumatic arthritis may be the end result.
Now is a good time to address your concerns. An orthopedic evaluation may serve you well. X-rays of the ankle may be taken. This will show the joint spaces and articular surface of the joint. Any signs of joint space narrowing, uneven surfaces, or the presence of bone spurs may point to a diagnosis of arthritis.
Many people have significant signs of arthritic changes without symptoms, so doctors don't put a lot of stock in X-ray results. They can provide some additional information not possible with a physical exam.
After taking a history and conducting a physical exam, the orthopedic surgeon will be able to advise you of your treatment options. A physical therapist can help identify areas of weakness and instability and plan an appropriate rehab program. Muscle strengthening is important but treatment will also address joint proprioception (sense of position) needed to prevent chronic reinjury.
If there is too much ligamentous damage, surgery may be needed. A conservative rehab program is advised before having surgery, so that's the first step even for severely damaged soft tissue structures.