Anterior ankle impingement
Something catching in the front of the ankle joint

Anterior ankle impingement is something trapped in the front of the ankle joint. This usually means that something is caught inside the ankle during movement. It may be soft tissue or a bone protrusion (osteophyte).

An impingement at the front of the ankle joint is also called an anterior ankle impingement. Anterior indicates the location of the impingement; in the front. By impingement we mean trapping or catching. Therefore, an anterior ankle impingement is something caught in the structures at the front of the ankle.

Description of condition

The ankle joint consists of the tibia, the fibula and the so-called ankle bone (the talus). When something is caught in the ankle joint, tissue is wedged between the tip of the tibia and the ankle bone.

The ankle joint is surrounded by a capsule, known as the joint capsule. The ankle joint also contains a mucous membrane (synovium) that produces synovial fluid so that the joint can move smoothly. With an anterior impingement of the ankle joint, the joint capsule and the synovium at the front are irritated, which causes swelling. This may lead to impingement.

Two types of impingement are possible. We distinguish between a "bony impingement" (due to a bone spur) and a "soft tissue impingement" (due to any other tissue).

Cause and history

A bony impingement can be the result of ankle instability, or an injury to the ankle joint when a forceful movement was made moving the toes toward the lower leg. Repeated exertion of force on the same spot can lead to microtrauma of the joint surface. This means that the joint surface is repeatedly subjected to cases of minor damage.

The body will try to strengthen the damaged area by producing extra bone tissue (also called osteophyte formation). The resulting bone protrusion may become trapped. An osteophyte usually grows over time and can eventually break off. If it breaks off, the bone fragment will remain floating in the joint capsule, causing blocking of the joint.

A soft tissue impingement usually occurs after an ankle sprain in which the sole of the foot turned inward. This is called an inversion trauma. Repeated spraining may damage the joint capsule. The resulting thickening of the capsule and possible scar tissue may also become trapped in the ankle joint.

Signs & symptoms

After certain activities, swelling may occur at the front of the ankle. In addition, the ankle joint is further restricted in movement because the body tries to avoid an impingement.

Typical symptoms of anterior ankle impingement:

• Chronic or long-term ankle pain.
  
• A history of frequent sprains.
  
• Mobility limitations (movement restrictions).
  
• Swelling of the ankle after activity.
  
• Thickening of the joint capsule.
  
• Pain when pressing on the joint capsule.
  

The symptoms of bony impingement are usually present on the anteromedial - front inner - side of the ankle, while the symptoms of soft tissue impingement are usually felt on the anterolateral - front outer - side.

Diagnosis

The diagnosis of an anterior ankle impingement is made on the basis of the patient's story, looking at the history of ankle injuries and activities. After that, a physical examination will take place to get a clear view of the symptoms.

If a bony impingement is suspected, an X-ray may be taken to see if osteophytes are forming, and if so, to what extent. The X-ray can determine the size of the bone spur and whether a bone fragment has broken off.

A soft tissue impingement cannot be detected on X-ray because X-rays generally only show bone structures. If treatment of a soft tissue impingement fails to produce any results, an ultrasound examination may be performed to determine the reason.

Treatment

Initially, soft tissue impingement is treated with rest, physiotherapy, a brace and shoe adjustments. An injection is used if other therapies are not sufficient.

Following an ankle trauma (e.g. a sprain or strain), appropriate physiotherapy is important. The ankle can be trained and the ankle joint mobilized. This is particularly important if a serious sprain has displaced the ankle bone. This displacement can put pressure on the capsule at the front of the ankle, which may later cause impingement symptoms because the capsule becomes irritated and thickened.

A brace may be recommended if ankle sprains happen regularly during (sports) activities.

If there are problems with the position of the foot, a shoe insert may be a good solution. It is therefore important to examine the ankle joint, the foot and the entire lower leg. Based on the findings, a treatment program can be started. Repeated sprains increase the risk of anterior ankle impingement, so it is important to examine the foot and ankle at an early stage.

If a bony impingement is suspected, it may be decided to perform surgery to remove the bone spur, following an X-ray. Any bone fragments that broke off should also be surgically removed.

Exercises

You can check your symptoms using the online physiotherapy check or make an appointment with a physiotherapy practice in your locality.

References
Vaseenon, T. & Amendola, A. (2012). Update on anterior ankle impingement. Curr Rev Musculoskelet Med (2012) 5:145–150.