When ankle pain continues for 6 weeks or more, it is considered chronic. The most appropriate first imaging test is an x-ray. X-rays provide general information about bone and tissue abnormalities. It is almost always the only imaging test of the ankle needed.
In people who have ankle arthritis and have pain that requires treatment, it may be appropriate to figure out which of the joints in the ankle is causing the pain. Either CT or MRI without contrast is appropriate to locate the joint causing the pain. Using imaging to guide a needle to inject anesthetic in the area of the pain to help confirm the cause is usually appropriate, too.
Some chronic ankle conditions cannot be seen on x-ray. When these conditions are suspected, MRI without intravenous contrast is appropriate. CT or MR arthrography may also be appropriate, in which case an x-ray dye is injected before the test is performed. These conditions include:
- Osteochondral lesion: an injury affecting the talus bone (a supporting bone in the ankle) and the surrounding cartilage. CT or MRI may be appropriate.
- Tendon abnormality: inflammation of the tendon, commonly known as tendonitis. Ultrasound or MRI may be appropriate.
- Ankle instability: residual wear and tear on the ligaments makes the ankle unstable. Ultrasound or MRI may be appropriate.
- Ankle impingement syndrome: overuse and microtears of the tendon causing pain and limiting ankle range of motion. MRI, CT or ultrasound may be appropriate.
- No obvious suspected disorder: MRI, CT, ultrasound, or image-guided local anesthetic injections may be appropriate.