Mastering Ankle Impingement Syndromes

Impingement syndromes can result in chronic ankle pain. Initially described as “athlete’s ankle” and “footballer’s ankle,” these syndromes have been associated with athletic activities such as soccer, running, volleyball, high jumping and ballet dancing.1-3 These syndromes can affect either the anterior or posterior aspect of the ankle joint and its causal pathway can be of soft tissue and/or osseous origin.

Only one reported study describes impingement syndromes occurring concurrently at the anterior and posterior ankle.4 Patients will usually complain of painful limitation with ankle range of motion. As with all patients presenting with ankle pain, one should obtain a detailed patient history. In addition, the clinician should possess a good working knowledge of ankle pathologies to ensure accurate recognition and diagnosis.

Anterior Ankle Impingement: What To Look For In The Physical Exam
Patients will often complain of vague, chronic anterior ankle pain, swelling after activity and limited dorsiflexion.5 Impingement symptoms at the anterior ankle may affect the medial or lateral aspect of the joint. Accordingly, one must clarify this with the physical exam. Tol, et al., described three distinctive regions or sections of the anterior ankle joint line: central, anteromedial and anterolateral.6

The central region is the area between the medial border of the tibialis anterior tendon and the lateral border of the peroneus tertius tendon at the ankle joint line. The anteromedial region is medial to the tibialis anterior tendon at the joint line and extends toward the medial malleolus. The anterolateral region is lateral to the peroneus tertius tendon at the ankle joint line and extends toward the lateral malleolus.

Eliciting pain upon palpation at a particular region of the anterior ankle joint line assists in differentiating between anteromedial and anterolateral impingement. However, due to coverage of the central region by neurovascular structures and tendons, this part of the ankle is difficult to assess by palpation.6 The clinician may palpate and appreciate the presence of osteophytic changes with the ankle in slight plantarflexion.

What About Recurrent Traction Of The Anterior Joint Capsule?
Researchers have postulated that osteophytic formation partially contributes to the development of anterior ankle impingement.7 Other authors initially attributed the development of osteophytes at the anterior ankle joint to repetitive traction of the anterior joint capsule.2,5,8,9 They believed that repetitive traction on the capsular and ligamentous structures at the anterior joint line with extensive plantarflexion movements lead to traction spur formation, which is particularly common among athletes. Typically, bony spur formation occurs at a ligament, tendon or capsule insertion, and its growth follows the direction of the natural traction pull of these soft tissue structures.10

However, arthroscopic studies have noted that the anterior ankle spurs are invested and situated within the joint capsule at the articular margin rather than at the capsular insertion.7,11 A recent anatomic study by Tol, et al., described the ankle’s exact anatomic anterior cartilage rim, capsular attachment, anterior soft tissue component and their relativity to the anterior ankle joint.12 Their findings illustrate the anterior joint capsule attaching onto the tibia an average of 6 mm proximal to the anterior cartilage rim and at the talus approximately 3 mm from the distal cartilage border.

Given the fairly large distance between the arthroscopically observed location of anterior ankle joint spurs and the studied anatomic origins of the ankle joint capsule, the researchers concluded that the formation of talotibial spurs due to recurrent traction of the joint capsule is implausible.12

Other Key Considerations In The Development Of Anterior Ankle Impingement
Ballet dancers require hyperdorsiflexion to accomplish the demi-plie position which, in turn, can lead to direct contact and impingement of the anterior lip of the tibia on the talar neck.13,14 Repetitive impingement secondary to extreme dorsiflexion proliferates exostosis formation at the anterior ankle joint.15 This process can also occur in athletes such as baseball catchers and football linemen, who require an extensive degree of ankle dorsiflexion.

Chronic ankle instability and recurrent supination ankle sprains have also been linked with osseous or soft tissue anterior ankle impingement. In their study, Kim, et al., concluded that one should consider soft tissue impingement at the anterolateral gutter of the ankle in a patient with chronic anterolateral pain after an injury, regardless of the stability of the ankle.16 Repetitive microtrauma can result in hypertrophied synovial tissue and fibrosis in the anterolateral gutter of the ankle, thereby leading to pain and mechanical impingement.17

Van Dijk, et al., concluded that anteromedial impingement can arise between the medial malleolus and the medial facet of the talus in patients with rupture of one or more of the lateral ankle ligaments after an inversion injury.18 One may note osteophyte formation in the medial ankle compartment, notably at the non-weightbearing anterior cartilaginous rim of the distal tibia, the anterior tip of the medial malleolus and the opposite medial facet of the talus.18,19

Repetitive microtrauma to the anterior ankle joint can play a role in development of anterior ankle spur formation. A study and analysis of soccer players related recurrent ball impact at the anteromedial aspect of ankle with reactive spur formation.20 Recurrent kicking utilizing the anterior aspect of the medial malleolus is thought to induce inflammation, the development of scar tissue, calcification and subsequent spur formation.

Pain at the anterior ankle may likely be attributed to impingement of the soft tissue structures. The presence of osteophytic bone formation contributes to a decrease in the anterior joint space, thereby impinging the ankle joint soft tissue between the anterior distal tibia and talus during forced dorsiflexion.3 Repetitive impingement leads to subsequent changes in the soft tissue structures of the anterior ankle. Arthroscopic resection of soft tissue from the anterolateral ankle demonstrated proliferative synovitis and fibrotic scar tissue.21,22 Further histopathological analysis of the resected tissue showed synovial changes that were consistent with chronic inflammation. In advanced cases, mechanical impingement may mold the tissue into a hyalinized meniscoid lesion.23

A Closer Look At Posterior Ankle Impingement Syndrome
Posterior ankle impingement is impingement that occurs at the anatomical interval between the posterior tibial articular surface and the calcaneus.24 Researchers have compared the mechanism of injury to a nut in a nutcracker as the posterior talus and surrounding soft tissues can be compressed between the tibia and the calcaneus during plantarflexion of the foot.25 Any soft tissue and/or osseous structure in the interval between the posterior tibia, talus and os calcis can be involved in this process.26 Impingement may result from acute trauma or chronic repetitive stress as in overuse injuries.

Activities such as ballet dancing, downhill running and soccer may predispose patients to posterior impingement syndromes. These activities require extreme ankle plantarflexion, which can induce abnormal stress at the posterior ankle.

The presence of an os trigonum or prominent, elongated posterolateral talar process (Stieda’s process) can contribute to or become involved in posterior ankle impingement. Researchers have used the terms os trigonum syndrome, talar compression syndrome, posterior ankle impingement syndrome and posterior tibiotalar impingement syndrome in the literature to depict clinical findings related to chronic, repetitive bony impingement in the posterior aspect of the ankle.27,28 The literature reports frequency of an os trigonum in the population anywhere from 1.7 percent up to 11 percent.29-31

The mechanism of injury usually involves forced (hyper) plantarflexion of the ankle, thereby impinging the os trigonum between the posterior tibia and calcaneus.28 This mechanism may also produce a synchondrosis disruption of the os trigonum or fracture of the posterior or trigonal process of the talus (Shepherd’s fracture).32

In his study of ballet dancers, Hardaker found that in extreme plantarflexion, an os trigonum, a Stieda’s process, a prominent dorsal process of the calcaneus or the presence of adhered or loose osteophytes can occupy space within the posterior ankle joint and lead to soft tissue impingement.15 Hyperplantarflexion at the ankle joint leads to compression of adjacent synovial, capsular and/or ligamentous tissues against the posterior tibia. With repeated entrapment, the posterior soft tissue structures can undergo inflammatory changes, thickening and fibrosis with subsequent scarring and/or calcification.

Patients will complain of posterior ankle pain that intensifies with ankle range of motion. Physical exam findings include tenderness, swelling and stiffness at the posterior ankle that is aggravated with forced plantarflexion and/or dorsiflexion. Tenderness is anterior to the Achilles tendon and its calcaneal insertion.33,34 Pain symptoms result secondary to compression or micromotion of an os trigonum, fracture of an os trigonum or prominent posterior talar fracture, or compression of ligaments, thickened joint capsules and scar tissue between an os trigonum and the tibia or calcaneus.3 As previously mentioned, forced plantarflexion causes compression of the osseous or soft tissue structures at the posterior ankle (the nutcracker phenomenon). One may note pain with forced dorsiflexion and this is likely due to traction of the posterior capsular and ligamentous structures.

Pertinent Pointers On Helpful Imaging Techniques
Conventional radiography is practical and relatively inexpensive for imaging of osseous abnormalities related to ankle impingement syndromes. One can utilize standard ankle radiographs for visualization and detection of ankle joint osteophytes, joint abnormalities (e.g. tibiotalar joint space narrowing) and pathology involving a Stieda’s process or os trigonum. Lateral stress radiographs in maximum dorsiflexion may exhibit osseous impingement.25

Van Dijk, et al., described utilization of an oblique anteromedial impingement (AMI) radiograph for specific recognition of anteromedial osteophytes.35 One would take this radiographic view with the beam tilted in a 45-degree craniocaudal direction with the leg in 30 degrees of external rotation and the foot in maximal plantarflexion in relation to the standard lateral radiograph position. Center the beam anterior to the lateral malleolus.

Magnetic resonance imaging (MRI) and arthrography may be useful in assessing soft tissue and osseous disorders present in ankle impingement syndromes, and for ruling out other potential causes of ankle pain.36 In a comprehensive review of imaging techniques for ankle impingement syndromes, Robinson, et al., concluded that one can accurately assess anterior ankle capsular abnormalities and confirm possible concomitant injury via arthrographic cross-sectional imaging studies (CT or MRI). Magnetic resonance imaging may be most useful in posterior impingement syndrome as it can identify the relative contributions of the osseous and soft tissue components.25,37,38

Magnetic resonance imaging of the anterior ankle may demonstrate exact positioning of osteophytes within the ankle capsule, ligamentous scarring, focal synovitis and capsular thickening. At the posterior ankle, MRI findings can include talocalcaneal synovitis, bone marrow edema, flexor hallucis longus tenosynovitis, fracture of an os trigonum (represented by fluid in the synchondrosis) or Stieda’s process, and posterior capsular or ligament thickening.25,37,38 In regard to osteochondral defects, degenerative joint disease and intra-articular fractures of the ankle and subtalar joint, it is better to assess these with advanced imaging. Clinicians should identify them as they are distinct from impingement syndromes.

A Guide To Treatment Options
Conservative treatment of ankle impingement syndromes includes anti-inflammatory medication, activity modification, cast immobilization, physical therapy, shoe gear modifications, heel lifts and local corticosteroid injections. When conservative measures fail with the persistence of symptoms such as swelling, tenderness, limitation of motion and weakness, one should consider surgical management.

Researchers have described both open and arthroscopic techniques for the management of ankle impingement syndromes. A study comparison of open versus arthroscopic measures for anterior ankle impingement demonstrated that arthroscopy yielded shorter postoperative hospitalization and recovery times.39 Debridement measures for ankle impingement, whether through an open or arthroscopic approach, have shown good long-term symptomatic relief and return to activity, especially in patients who lacked preoperative tibiotalar joint space narrowing and osteoarthritis.7,8,11,40

While resection of hypertrophic synovial and scar tissue will reduce pain symptoms, Tol, et al., concluded that removal of osteophytes can restore anterior joint space, which reduces the likelihood of continued soft tissue compression and subsequently decreases the chance of recurrence.7

The primary goal of operative treatment for posterior ankle impingement is excision of the impeding anatomical structure. One should remove a fractured os trigonal or posterolateral talar process in its entirety. If symptoms are caused by chronic posterior bony impingement of the os trigonum, Stieda’s process or posterolateral talar process, surgeons should remove the entire portion of bony involvement.27

In addition, it is important to excise any noted hypertrophic synovium, fibrosis and scar tissue. Both arthroscopic and open approaches have yielded good results for operative management.3,26,28,33,41-43 Arthroscopic approaches offer the inherent advantage of shorter recovery time.41 In general, a medial open approach is advocated if the surgeon needs to address concomitant flexor hallucis longus (FHL) tendon pathology (e.g. tenosynovitis, attenuation, tear) and posterior bony impingement.27 One may release the fibro-osseous tunnel of the FHL if necessary. Utilize a lateral open approach if you only need to address a posterior bony pathology.

After performing an open approach, one should place patients in a neutral short leg posterior splint dressing with crutch ambulation. Have the patient maintain crutch gait until suture removal. Longer use of crutches is encouraged if tendon repair is part of the surgical procedure to permit tendon healing. One may encourage arthroscopically managed patients to bear weight as tolerated immediately after the procedure. Physical therapy can facilitate postoperative recovery and rehabilitation. Progressively increase the return to activity over time as tolerated.

In Conclusion
The mechanisms leading to ankle impingement syndromes are not fully understood. The diagnosis of ankle impingement is based on the clinical history, physical exam findings and exclusion with or without the necessity of advanced imaging techniques.
Advanced imaging techniques can assist in diagnostic confirmation of a suspected ankle impingement syndrome. However, in addition to the expense, the literature demonstrates these modalities lack consistent findings and yield low sensitivity and specificity in diagnosing ankle impingement syndromes.

Recent literature advocates the use of arthroscopic management in ankle impingement syndromes due to decreased recovery periods. Both open and arthroscopic approaches have yielded good results for posterior ankle impingement syndromes.

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