Research Review By Gary J. Maguire©

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Date Posted:

November 2011

Study Title:

Review of common and unusual causes of lateral ankle pain

Authors:

Chourdhary S, McNally E

Author's Affiliations:

Musculoskeletal Radiology, Nuffield Orthopaedic Centre & University of Oxford, United Kingdom

Publication Information:

Skeletal Radiology 2011; 40: 1399-1413.

Background Information:

The ankle is the most frequently injured peripheral joint, and among these injuries, the most common is an inversion sprain, an injury that frequently presents in our offices or even emergency departments (1). In the lateral ankle, the most common causes of pain include: lateral ligament injury, fibular (peroneal) tendon injury, sinus tarsi syndrome and nerve entrapment syndromes.

While this review article is primarily aimed at helping radiologists approach a patient with lateral ankle with differential diagnosis with ultrasound and MR imaging, it does provide clinicians with guidance in identifying and clarifying unusual patterns of pain or intractable symptoms associated with ankle injuries. While many individuals respond with conservative intervention, 10-20% of patients continue to have lateral ankle pain and instability after injury, highlighting the need for appropriate diagnosis and management (2).  Before proceeding, it would be a good idea to review the anatomy of the lateral ankle region.
lateral_ankle_ligamentslateral_ankle_muscles

Pertinent Conditions:

Fibular (Peroneal) Tendon Disorders:
  • Fibular tendinopathy (tenosynovitis, subluxation and tendon rupture) can manifest as an important cause of persistent lateral ankle pain following injury and should be carefully evaluated during clinical examination. While isolated fibular tendon tears are infrequent, they are often a result of an inversion injury. Fibular tendon tears are typically associated with ankle instability, ankle or forefoot fractures and fibularis longus/brevis tenosynovitis. It is also important to note that a number of anatomic variants predispose to the development of fibular tendinopathy which may include: a shallow or convex retromalleolar groove, an anatomically low (distal) musculotendinous junction, posterolateral spurring in the fibula, cavovarus position of the foot, or a peroneal tubercle greater than 5 mm in height.
  • Fibularis quartus presents as an accessory fibular muscle and is a frequent variant of the ankle and foot with a reported incidence varying from 6.6 to 21.7%. The presence of this variant should be considered as it may contribute to stenosis of the retromalleolar groove and predispose to fibular tendon tears. As a side note, when present it can also be potentially used in reconstructive surgery.
  • Peroneal/fibular muscle subluxation can result from post-traumatic laxity of the superior peroneal retinaculum. This insult occurs due to elevation of its attachment to the periosteum of the fibula allowing hypermobility of the fibularis brevis tendon. Individuals may also be predisposed to this when a flat posterior fibular groove is present or a calcaneovalgus foot. Classification of this disorder is as follows:
    1. Type I: periosteal elevation along the fibula
    2. Type II: a tear of the fibular attachment
    3. Type III: an avulsion fracture at the fibular attachment; and
    4. Type IV: involves a tear of its posterior attachment
    Type I and III are the most common. Patients often describe this as an insidious onset of chronic ankle pain with active foot eversion (+/- crepitus). There are two types of non-subluxation events where the tendons remain within the retrofibular groove, but their relative relationship changes. What occurs is the tendons switch position with respect to each other and the fibularis longus moves to lie deep to the brevis (Type A) with a visible snap during movement. Type B refers to an intersheath subluxation where the fibularis brevis splits longitudinally and the longus subluxes anteriorly through the split. Corrective surgery for acute and recurrent fibular tendon subluxation has good long-term results compared to non-operative intervention.
  • Os perineum (an oval or round accessory ossicle present in the distal longus tendon near the cuboid) is present in approximately 20% of individuals. It often remains asymptomatic. When aggravated it has a potential cause of plantar lateral foot pain with varying mechanisms of onset including: an acute os peroneum fracture, diastasis, or stress changes in a bipartitie os peroneum. Progression may also lead to discontinuity of the fibularis longus tendon. The presence of a hypertrophic peroneal tubercle on the lateral aspect of the calcaneus may entrap the peroneus longus tendon and/or the os peroneum during tendon excursion. Suspicion of this condition warrants diagnostic imaging.
  • Cuboidal fossa syndrome can emerge due to a high shear stress as the fibularis longus tendon passes deep to the cuboid in a fibro-osseous tunnel. Fibularis longus tenosynovitis and tendinopathy may also occur as a result of bone marrow edema of the cuboid, erosions, and periosteal reaction along the cuboid.
  • A fracture at the base of the 5th metatarsal may also occur and is classified into two groups: those involving the tuberosity, and fractures involving the proximal part of the diaphysis distal to the tuberosity (Jones’ fracture). Fifth metatarsal tenderness may also be due to inflammation involving the lateral insertion of the lateral band of the plantar fascia. Imaging is warranted if this is suspected.
Ligament Injuries:
  • The anterior talofibular ligament (ATFL) is typically the first structure to be injured in inversion ankle injuries. It forms the anterior part of the lateral collateral ligament complex. Following insult the ligament can be identified as lax (Grade 1 sprain), attenuated (Grade 2) or discontinuous (Grade 3). With chronic injury the ligament may develop a synovial mass and anterolateral impingement.
  • Calcaneofibular ligament injuries often occur with more severe inversion stress and often is associated when there is more severe ATFL involvement. To a lesser degree the posterior talofibular ligament (PTFL) may become injured when these associated ligaments are involved. This will present as increased laxity on orthopedic examination and is best assessed with MRI.
  • Anterolateral impingement often is a result of chronic ankle inversion injuries. This impingement is the result of a cascading effect where injury to the ATFL predisposes to chronic enthesopathy, ligament attrition, or hypertrophy. This may lead to a synovial mass formation in the anterolateral gutter with the onset of impingement and pain along the lateral ankle joint. Some research indicates that the presence of abnormal anterolateral gutter soft tissue does not imply symptomatic anterolateral impingement (3). Treatment of a symptomatic nodular mass (often >10mm) typically involves injection therapy in a single sitting procedure. (EDITOR’S NOTE: Many clinicians forget about this condition. It can present with anterolateral ‘pinching’, particularly with passive dorsiflexion +/- eversion. You may feel fibrosis or even a nodule in the joint capsule or AFTL. Soft tissue work is often very helpful for this condition in my experience.)
  • Syndesmotic injuries have a varying incidence rate of 1-20% with repeated ankle sprains and severe ankle trauma. The anterior inferior tibiofibular ligament (AITFL) is the stabilizing force and creates the distal tibial syndesmosis. The AITFL is the ligament most vulnerable to injury and is referred to as a syndesmotic injury (see Related Reviews below for a review on Syndesmosis Injuries).
  • Those who participate in activities involving plantar flexion (e.g. ballet dancers or gymnasts) may experience an onset of posterolateral impingement. This occurs with synovitis, capsulitis, or fibrosis involving the posterior ankle ligaments. This type of impingement is most often caused by hypertrophy or a tear of the posterior inferior or transverse tibiofibular ligaments.
  • The sinus tarsi ligaments provide stability to the lateral ankle and hindfoot. When this region is injured (primarily from trauma) it is referred to as sinus tarsi syndrome. It often is a non-specific group of lesions that cause pain that radiates from the sinus tarsi. With ongoing chronic ankle pain this syndrome may develop creating ankle instability and pain. Some other causes that contribute to this syndrome are: rheumatoid arthritis, ankylosing spondylitis, gout, and foot deformities such as pes planus or the development of ganglion cysts.
Nerve Injuries:
  • Pain and parasthesia experienced along the lateral ankle and foot are often caused by sural neuropathy. This should be considered as a potential dual pathology if symptoms persist or are atypical over the injury site. This dual pathology may be a result of fractures to the base of the 5th metatarsal, cuboid, calcaneum, Achilles tendinopathy, or fibular tenosynovitis. Complications may also arise with the development of traction neuroma following surgery for fibular tendon disease or incisional entrapment of the sural nerve. This often results in pain and sensory loss.
  • Residual dorsolateral foot pain following an ankle sprain can be due to entrapment (under the fibroadiposal fascial sheath deep to the extensor digitorum brevis and over the head of the talus) of the lateral branch of the deep fibular nerve. Osteophytosis or ganglion cysts may also develop involving the medial or lateral branch of the deep fibular nerve and lead to impingement. A post-traumatic neuroma of the deep fibular nerve branches is also associated with persistent ankle pain. This is often treated with a nerve block and selective resection of the appropriate branch, normally leading to good functional outcome.
  • The superficial fibular nerve can also become entrapped. This is often a result of thickening of deep fascia due to injury in athletes and dancers. Tenting of the nerve occurs due to a fascial defect and secondary herniation of the fibularis longus muscle. Symptoms that emerge are tingling and numbness along the lower leg and dorsum of the foot (sparing the first web space which is innervated by the deep fibular nerve). Another mechanism of injury is when it is stretched during inversion or plantar flexion ankle injuries. This often results in perineural fibrosis and chronic ankle pain.
Bony Injuries:
  • Injuries as a result of an inversion and plantar flexion injury (with bony avulsion at the origin of the bifurcate ligament) can lead to a fracture of the anterior process of the calcaneus. If not detected early this can lead to a painful non-union. An impaction type of injury due to eversion and dorsiflexion can also contribute to fracturing this region. Research of anterior process calcaneal fractures has revealed that in patients having predisposing bony or soft tissue anomalies: 60% had calcaneonavicular coalition, 50% had a thickened anterior talofibular ligament, and 69% had thickening of the bifurcate ligament.
  • Although uncommon, fractures to the cuboid may occur due to trauma to the forefoot in forced abduction. They may be associated with fractures involving the navicular and os calcis.
  • Lateral ankle pain can also present due to osteochondral lesions of the talus. These types of lesions often are located at the superomedial or superolateral corners. Intact cartilage and absent linear or cystic defects at the lesion base often suggest stability and allow for conservative treatment. On the other hand, surgical intervention may be required when: cartilage defects are present (with or without complete separation of the fragment), fluid is present around an undetached fragment, or there is a dislodged fragment.
  • In 1% of the population an os subfibulare may be present. This bone variant is related to the tip of the lateral malleolus (a result of an accessory ossification center or an avulsion fracture of the anterior talofibular ligament). Avulsion fractures create laxity of the anterior talofibular ligament or ankle instability and symptoms are localized tenderness at the ossicle.
  • Injuries that result in repeated ankle sprains, lateral foot pain and peroneal spastic flat foot may result in calcaneonavicular coalition (CNC) and “too long anteromedial process” of the calcaneous (TLAP). The anteromedial process of the calcaneus when elongated becomes interposed between the head of the talus and the cuboid. This elongation may be far enough to cause impingement on the navicular. Due to this elongation, supination produces a “nutcracker” phenomenon with compression of the process between the talus and the cuboid. This often results in a chondral injury of the head of the talus at its inferior and lateral part which faces the TLAP (often present in adolescents with recurrent ankle sprains).
Mass Lesions & Miscellaneous:
  • Injuries specific to elite figure skaters and snowboarders are shoe rim/shoe buckle pseudotumors which present as a painful soft tissue swelling. This is often present over the lateral supramalleolar region. The development of this condition is attributed to subcutaneous fat impingement between the fibula and the shoe rim.
  • The authors also acknowledge other conditions that usually cause generalized pain but may present with lateral pain which may include: ankle and subtalar joint osteoarthritis, infection, soft tissue tumors and tumor-like conditions.

Clinical Application & Conclusions:

As mentioned, inversion sprains are the most common lateral ankle injury. As such, they are likely the most common injury we might encounter in practice. In patients with severe inversion injuries, surgical intervention may be indicated. Lateral ligament reconstruction may be necessary when disabling symptoms due to chronic instability persist, or if clinical examination indicates (anterior drawer sign, varus tilt test), or with positive stress radiographs. When surgery is required, the most commonly performed procedures are:
  • Broström procedure: This involves reconstruction of torn ATFL or CFL by shortening and approximation of the ruptured ends. This can also include attaching the shortened ligament onto the fibula through drill holes, or suturing of the lateral extensor retinaculum to the distal aspect of the fibula. Grafts from the gracilis or plantaris tendons may also be used.
  • Chrisman-Snook repair: This type of procedure is for non-anatomic reconstruction where the peroneus brevis is substituted for the involved ligament. The ATFL and CFL are repaired with spit tendodesis of the fibularis brevis. This is a technically challenging intervention but has good results. The limitation is a loss of inversion and eversion due to non-anatomical placement of tissue across the joint.
  • Evans procedure: This involves reconstruction of the CFL and involves proximal transaction of the fibularis brevis tendon, re-routing through a vertical oblique fibular tunnel in a distal to proximal direction. It is then reattached at the site of the initial transaction. This technique results in allowing varus tilt without anterior hypermobility.
When fibular tendon tears occur conservative management (immobilization in a short leg walking cast) has not been shown to be very successful. When chronic lateral ankle symptoms persist other factors need to be considered and can often be revealed with MR imaging or ultrasound. When surgical reconstruction is involved complications can emerge. Such complications may involve ankle and subtalar stiffness, laxity, failure of repair or sural nerve injury. Practitioners should keep this in mind when chronic ankle pain is present.

From a rehabilitation perspective it is important to remember that the interaction between the static and dynamic components of functional ankle stability is mediated by the neuromuscular system. Rehabilitation needs to also focus on improving proprioception through neuromuscular training of the mechanoreceptors. With injury to the joint structures and supporting ligaments, there is disruption of the mechanoreceptors which results in a partial deafferentation of the joint. Consequently, neuromuscular control is compromised as a result of abnormal firing of the injured mechanoreceptors. Without adequate preparatory activity, the static structures may be exposed to insult unless reactive muscle activity can be initiated to contribute to dynamic restraint.

Study Methods:

This was a narrative literature review.

Study Strengths / Weaknesses:

This review provides strong insight into the analysis of common and unusual causes of lateral ankle pain, the use of ultrasound and MR imaging techniques to identify pathologies and clear anatomical analysis of each disorder.

Additional References:

  1. Garrick, JG. Epidemiologic perspective. Clin Sports Med. 1982; 1: 13-18.
  2. Becker, HP, Rosenbaum, D. Chronic recurrent ligament instability on the lateral ankle. Orthopaedics. 1999; 28: 483-492.
  3. McCarthy, CL, Wilson, DJ, Coltman, TP. Anterolateral ankle impingement: findings and diagnostic accuracy with ultrasound imaging. Skeletal Radiol. 2008; 37 (3): 209-216.