Anterior Ankle Impingement
Edited by Judith Smith, MD
Background and Clinical Presentation
Anterior ankle impingement is the most common cause of pain in the front of the ankle joint (Figure 1). In this case, “impingement” describes an increase in pressure or impact at the front (anterior) of the ankle joint while walking. The associated pain is typically proportional to weight-bearing activity. However, it is usually worse with the first few steps after getting out of bed in the morning or after sitting for a while (referred to as “start-up” pain). This increase in pressure (impingement), may be caused by calf tightness where one (gastrocnemius) or both (gastrocnemius and soleus) of the calf muscles are tight. Together, the end of the shin bone (tibial plafond) and the lower bone of the ankle joint (talus) form the primary weight-bearing surface of the ankle joint. While walking, as the body progresses over the foot, the increased tension on the Achilles tendon prevents the roof of the ankle (tibial plafond) from gliding over the talus. Instead, the front of the tibial plafond impacts or impinges on the joint surface of the talus. This impingement not only causes pain but, may begin to cause the breakdown of joint cartilage between the two surfaces (arthritis). Left unchecked, the irritation to the joint often results in the formation of bone spurs. Bone spurs form in response to increase joint pressure and irritation. Spurring of the tibial plafond typically appears as a “beak” or “awning” extending from the end of the upper bone of the ankle joint (tibia). On the talus side, the spur usually looks like a bump in front of the ankle. These spurs are seen on lateral x-rays of the ankle and serve to physically block upward ankle motion (Figure 2).
The causes of anterior ankle impingement are related to any condition that leads to bone spurs in the front of the ankle. Potential causes include: ankle arthritis or aleading to bone spur development.
Figure 1: Location of Pain in Anterior Ankle Impingement
Figure 2: Impingement “Jamming” in the Front (Anterior) Ankle
Anterior ankle impingement may result in narrowing of the joint space by damaging joint cartilage. Later, the bone spurs at the front of the ankle can be seen on an ankle x-ray taken from the side (lateral view). The size of the bone spur can vary from very small to quite large (Figure 3). X-rays may also demonstrate mild, moderate, or even severe ankle arthritis.
In early impingement, MRI may demonstrate inflammation or fluid accumulation in the bone of the ankle joint. However, in the absence of findings on plain x-rays, the diagnosis is fairly straightforward and based on physical examination.
Figure 3: Anterior Ankle Bone Spurs
Early on, treatment should focus on stretching of the calf muscles in an effort to reduce the tension on the Achilles tendon and improving ankle motion. In some, patients physical therapy may be helpful to overcome changes in walking habits that may have developed and contribute to this condition. Depending on the severity and the patient’s physical demands, symptoms may be improved considerably by modifying activity. Some potentially effective non-operative treatments are:
- Calf Stretching: regular stretching of the calf can be very beneficial. This is done in an effort to decrease the tension on the Achilles and to increase ankle motion.
- Use of a Slightly Elevated Heel: Using a shoe with 1-1.5” heel (or adding a heel lift inside the shoe) means that the foot does not need to come up as far in the course of normal walking. Therefore, less impingement occurs and patients will tend to be less symptomatic.
- Activity Modification: If appropriate, avoiding or limiting activities (i.e. certain sporting activities or walking uphill) that cause ankle jamming will tend to cause the symptoms to improve.
- Anti-inflammatory medication (NSAIDs): The use of anti-inflammatory medication (assuming no contra-indications) can be helpful if persistent symptoms are present.
- An occasional injection of corticosteroid into the ankle joint may be helpful, particularly if there is some underlying ankle arthritis present.
Note well: While improving symptoms, these efforts will not address the cause of anterior ankle impingement.
The focus of operative treatment is to remove the impinging bone spurs at the front of the ankle and increase ankle motion thereby decreasing the pressure created in the front of the joint during walking. This may be accomplished removing the spurs blocking motion, and by lengthening the gastrocnemius tendon in cases where there is a large difference in ankle dorsiflexion (upward motion of the foot relative to the leg).
Edited on October 6, 2018