What is Anterior Ankle Impingement
Anterior ankle impingement, originally nicknamed “footballer’s ankle” and later known as “athlete’s ankle” is a source of chronic ankle pain seen in athletes. It occurs when bone spurs, or osteophytes, develop on the front (anterior) aspect of the bones of the ankle. When this occurs an athlete may develop symptoms from the osteophytes impinging on each other or by pinching soft-tissues between them. Well known athletes with recent surgery for anterior ankle impingement include Brian Westbrook of the Philadelphia Eagles and Keith Rivers of the Cincinnati Bengals.
Who gets Anterior Ankle Impingement?
Anterior ankle impingement typically occurs in athletes who have played years in sports that involve a kicking motion and therefore repeated ankle extremes of motion either up (dorsiflexion) or down (plantarflexion). This is typical in soccer players, but has since been described to occur in american football, volleyball, ballet and runners. All of these sports involve forceful ankle joint motions that place tremendous pressure on the joint itself. As this is an overuse injury that slowly progresses over time, symptomatic athletes tend to have participated in their sport for a long period of time and are often at least 25 years of age. Interestingly nearly half of all high level athletes involved in sports considered at risk for developing anterior ankle impingement, have bone spurs as seen on xrays despite having no symptoms. It is not entirely clear why some athlete’s develop the onset of pain while others can continue to compete without difficulty.
What is the relevant anatomy of the ankle?
The ankle joint is composed of two bones that glide and pivot on one another, the tibia and the talus. There is also a thick covering that surrounds the entire ankle joint, known as a joint capsule, that keeps joint fluid (synovial fluid) within the joint. The synovial fluid along with the smooth cartilage that lines the ends of each bone within the joint allows the ankle joint to move with very low friction.
Some athletes develop bone spurs (osteophytes) on the front (anterior) edge of the bone of the ankle. How and why these spurs form is unclear. They are similar to bone spurs that form with arthritis, however ankle impingement is not always associated with advanced arthritis of the ankle. They may be due to repeated tugging of the joint capsule on the front lip of the tibia or from cumulative repetitive injury during athletics. Lastly, there is also evidence that this process is accelerated with repeated ankle sprains. In any case, the bone spurs pinch together when the ankle is flexed back (dorsiflexed) and joint capsule and synovium (the lining of joints) becomes pinched. This repetitive pinching of soft tissue is what is believed to be the source of pain in anterior ankle impingement.
How do you diagnose Anterior Ankle Impingement?
The athlete will complain of longstanding chronic pain in the front of his or her ankle that is worse with playing sports. They will often have sustained many ankle sprain injuries, particularly where the ankle turns in (inversion sprain). The pain will be worse with bending the ankle back and therefore the athlete, if involved in kicking sports like soccer, will have difficulty with the normal form for kicking the ball. On the other hand, they will have much less difficulty kicking the ball with their ankle and foot pointed downward (plantarflexion). An athlete may also complain of recurrent swelling present in the front of the ankle after athletic participation. Their symptoms often cause an athlete to decrease their athletic involvement as well as their level of play.
The symptoms may be predominantly on the inside (anteromedial) or outside (anterolateral) of the ankle. This can be distinguished on exam by palpating for tenderness along the front of the ankle joint and locating the area of maximal tenderness. Also on exam the bone spurs can sometimes be palpated if the patient is not too swollen or of too large body habitus. Forced ankle dorsiflexion in an attempt to recreate the irritating process may or may not recreate the athlete’s symptoms on exam.
What imaging studies are useful?
Standard ankle radiographs are necessary and are the mainstay of imaging anterior ankle impingement. The xray view of the ankle from the side (lateral radiograph) shows the ankle in profile and the bone spurs can be seen. Sometimes when the spurs are located on the inside of the ankle (anteromedial), they can be difficult to see on the standard lateral radiograph. Therefore an xray taken at a slight angle (oblique radiograph) can be helpful in seeing these anteromedial bone spurs more easily.
MRI is a useful test for a couple of different reasons. First, it can be useful in being sure there is no other cause of foot or ankle pain present that can mimic anterior ankle impingement or be an additional symptom generator. Other findings could include:
● Occult (hidden on xray) stress fractures
● Osteochondral lesions (injury to the bone and cartilage of the ankle joint surface)
● Tarsal coalition (abnormal fusion between 2 normally separate bones in the foot)
Also an MRI may show signs of swelling in the region of irritation in the front of the ankle. This can help confirm the findings in the patient’s history and physical exam as well as help with surgical planning in the future.
How can Anterior Ankle Impingement be treated?
Initial treatment for anterior ankle impingement should be non-operative. This should consist of a period of avoidance of activities that cause the symptoms. This may involve time off from athletic participation. During this time, the athlete should still be active in conditioning in ways that do not recreate forceful ankle motion or aggravate their symptoms. Regular oral anti-inflammatory use along with the regular use of an ice pack are important to treat any swelling present.
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The use of intra-articular corticosteroid injections can also be considered although should not be repeated too often because of potentially deleterious effects on the articular cartilage within the ankle joint. A performance evaluation by a highly trained physical therapist can be helpful. They can work with the athlete and alter their lower extremity motion and therefore the mechanical factors at play. It is important that they be knowledgeable about the specific sport the athlete participates in.
What does surgery for Anterior Ankle Impingement typically consist of?
If non-operative treatment for anterior ankle impingement is unsuccessful, as it often is, then surgical treatment should be considered. Another reason for earlier operative treatment would be the timing of the athlete’s symptoms in relation to their current season as well as the next one. Whether or not surgery is indicated depends on a thorough evaluation by a sports medicine trained or foot and ankle trained orthopaedic surgeon. Surgery normally consists of removing the bone spurs in the front of the ankle as well as removing any inflamed soft-tissue in the region.
Surgery is usually performed arthroscopically through a few very small incisions and using a video camera for assistance. Occasionally, at the discretion of the treating surgeon, a more traditional larger incision is necessary to remove the bone spurs and scar tissue. The procedure is typically performed as an outpatient.
What does the post-surgical recovery involve?
Immediately following surgery there is a short period of relative immobilization of the ankle. This allows the incisions to heal and the post-operative swelling that occurs to decrease with frequent elevation. Following this period, structured physical therapy with a progression to sports-specific training is utilized to get the athlete back to competition. The time back to full competition varies, but typically takes 3 to 6 months.
What is the prognosis and timing for recovery after surgery?
80 to 90% of athletes who undergo surgery for anterior ankle impingement are improved following surgery and return to play their sports at the same or higher level as before their injury. About 2/3 of patients who undergo removal of bone spurs and debridement of inflamed tissue have a recurrence of the bone spurs as seen on xrays. However they are not usually symptomatic. Patients who have evidence of ankle arthritis at the time of their surgery are improved with surgery for their ankle impingement, but the outcomes are not as good as when there is no arthritis present.
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C. Niek van Dijk and Christiaan J. A. van Bergen. Advancements in Ankle Arthroscopy J. Am. Acad. Ortho. Surg., November 2008; 16: 635 – 646.