Fibulocalcaneal Pain Syndrome – The Clinical Syndrome
Fibulocalcaneal pain syndrome is the result of injury to the fibulocalcaneal ligament, usually caused by sudden inversion of the ankle, as when stepping off a high curb.
The fibulocalcaneal ligament, which is also known as the calcaneofibular ligament, runs from the apex of the fibular malleolus downward and slightly backward to a tubercle on the lateral surface of the calcaneus, and is susceptible to strain from acute injury secondary to repetitive microtrauma to the ligament resulting from overuse or misuse, such as long-distance running on soft or uneven surfaces. Patients with fibulocalcaneal pain syndrome report pain anterior and inferior to the lateral malleolus. Inversion of the ankle joint exacerbates the pain.
Signs and Symptoms
Point tenderness is felt just below the lateral malleolus on physical examination. With acute trauma, ecchymosis over the ligament may be noted. Passive inversion of the ankle joint exacerbates the pain. Coexistent bursitis and arthritis of the ankle and subtalar joint may be present and confuse the clinical picture. Stress fractures of the foot also occur with increased frequency in runners, and this must be considered in all patients thought to have fibulocalcaneal pain syndrome.
Plain radiographs are indicated in all patients with ankle pain. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging (MRI) and ultrasound imaging of the ankle is indicated if disruption of the fibulocalcaneal ligament, joint instability, occult mass, or tumor is suspected as well as to confirm the diagnosis.
Avulsion fractures of the calcaneus, the talus, the lateral malleolus, and the base of the fifth metatarsal can mimic the pain of injury to the fibulocalcaneal ligament. Bursitis, tendinitis, and gout of the midtarsal joints may coexist with ligament strain and may confuse the diagnosis. Tarsal tunnel syndrome may occur after ankle trauma and may further confuse the clinical picture.
Initial treatment of the pain and functional disability associated with fibulocalcaneal pain syndrome should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold may be beneficial. Avoidance of repetitive activities that aggravate the patient’s symptoms and short-term immobilization of the ankle joint may provide relief. For patients who do not respond to these treatment modalities, injection of the fibulocalcaneal ligament may be a reasonable next step. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.
Complications and Pitfalls
Failure to identify occult fractures of the ankle and foot may result in significant morbidity. Radionucleotide bone scanning and MRI of the ankle should be performed on all patients experiencing unexplained ankle and foot pain, especially if trauma is present. The major complication of the previously mentioned injection technique is infection. This complication should be exceedingly rare if strict aseptic technique is followed. Approximately 25% of patients report a transient increase in pain after injection of the fibulocalcaneal ligament, and patients should be warned of this possibility. Injection around strained ligaments always should be done gently to avoid further damage to the already compromised ligament.
It is estimated that approximately 25,000 individuals in the United States sprain their ankle every day. Although viewed as benign by the lay public, ankle sprains can result in significant permanent pain and disability. The major ligaments of the ankle joint include the deltoid, anterior talofibular, calcaneofibular, and posterior talofibular ligaments, which provide most of the strength to the ankle joint. Injection of the fibulocalcaneal ligament is extremely effective in the treatment of pain secondary to fibulocalcaneal ligament strain. Coexistent arthritis, bursitis, and tendinitis also may contribute to medial ankle pain and may require additional treatment with more localized injection of a local anesthetic and depot steroid. The use of physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes the injection technique for ankle pain. Vigorous exercises should be avoided because they would exacerbate the symptoms. Simple analgesics and NSAIDs may be used concurrently with this injection technique.