Chronic Lateral Ankle Pain

The definition. Lateral-sided ankle pain persisting beyond six months, most often following an inversion injury, with or without a sense of giving way. The task is to decide whether the pain arises from the ligament, the joint surface, the tendons, the bone or the hindfoot alignment, and the chronically painful ankle is usually a diagnosis that was never made rather than a failure of healing.

Where exactly. The point of maximal tenderness carries more diagnostic weight than any imaging. Palpate with one finger and make the patient localise to a single point rather than accepting "the outside of my ankle", then reproduce the pain deliberately with the manoeuvre that provokes that site rather than relying on the history of what hurts. Five sites cover the lateral ankle:

• Anterolateral gutter — anterior to the fibula, at the ATFL and the anterolateral capsule. Reproduced by forced dorsiflexion with eversion. Impingement or the ATFL.
• Retrofibular — behind the distal fibula along the peroneal groove. Reproduced by resisted eversion and by circumduction, looking for subluxation. Peroneal.
• Sinus tarsi — a fingerbreadth anterior and inferior to the lateral malleolar tip. Focal, deep, worse on uneven ground, with a painful passive inversion-eversion arc. The subtalar joint, sinus tarsi syndrome or an anterior process of calcaneus fracture.
• Just inferior to the fibular tip — below and slightly anterior to the tip, with pain on subtalar motion, after a dorsiflexion-inversion injury. Lateral process of talus fracture.
• Posterolateral / posterior — the os trigonum and FHL, reproduced by forced plantarflexion, not inversion. Posterior impingement.

Pain that is not at a point at all, a deep ache with swelling after activity and provoked by axial loading, comes from the joint surface: an osteochondral lesion.

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What mimics the pattern. Some pain is felt laterally but does not arise there:

• Referred pain from the subtalar joint — post-traumatic subtalar arthritis after a calcaneal or talar injury feels lateral but is worse on inversion/eversion, not on drawer.
• Base of fifth metatarsal / cuboid pathology — the patient points laterally but distally; tenderness is at the metatarsal base.
• Common peroneal or superficial peroneal nerve entrapment — burning, dysaesthetic, non-mechanical; positive Tinel over the fascial exit about 10 cm above the tip of the fibula.
• Complex regional pain syndrome — pain out of proportion, allodynia, vasomotor and sudomotor change; do not operate.
• Lumbar radiculopathy (L5/S1) — pain extends above the ankle and is reproduced by straight leg raise.

Weight-bearing AP, mortise and lateral, always first. They show arthritis, talar dome lesions, an os trigonum, the fifth metatarsal base, avulsion fragments and the joint space. Weight-bearing is essential, because non-weight-bearing films hide arthritis and syndesmotic widening. Normal tibiotalar, subtalar and syndesmotic alignment is established here, before subtle instability, impingement or osteochondral disease can be called.

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Are the films truly normal? Add a lateral oblique, then look deliberately at five sites: the talar dome corners, the anterior process of calcaneus, the lateral talar process, the fifth metatarsal base and the posterior talus. These are the occult lesions that present weeks later as persistent lateral pain having been called a sprain, and only after this search does a "normal film" justify cross-sectional imaging.

The two processes hidden by overlap. The anterior process of calcaneus and the lateral process of talus are hidden on a standard mortise view. The oblique profiles the anterior process and the anteater nose of a calcaneonavicular coalition, cheaply, and often avoids CT in the adolescent. Where tenderness is precisely localised to either process, the answer is CT rather than a repeat plain film, and for the lateral process CT rather than MRI.

Standing hindfoot alignment view (Saltzman). Quantifies varus or valgus of the heel relative to the tibial axis, and is obtained before any surgery.

MRI, the default when films are normal at 6-8 weeks. Best for osteochondral lesions, peroneal split tears, ligament attenuation, anterolateral gutter soft tissue, sinus tarsi fat obliteration and occult stress fracture. MR arthrography shows contrast traversing a full-thickness ATFL tear. Read it with the examination in hand: bone marrow oedema, mild peroneal fluid and ATFL thickening are common in asymptomatic athletes, so treat the point of maximal tenderness, not the report.

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CT, for bone architecture and occult fracture. The lateral process of talus, the anterior process of calcaneus, subtalar arthritis grading, talocalcaneal coalition and the pre-operative planning of an osteochondral lesion with a large cyst. It is superior to MRI for fragment size and subchondral bone: on an osteochondral fracture CT defines the fragment while MRI maps the cartilage defect and marrow oedema, and in coalition CT confirms and defines the osseous component when operative planning needs the exact extent.

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Dynamic ultrasound. The only test that demonstrates peroneal tendon subluxation in real time, and it allows a guided injection. Operator dependent.

Stress radiographs or stress fluoroscopy. Anterior drawer and talar tilt under stress. They rarely alter management, because the diagnosis of instability is clinical, but they are useful when the history and the examination disagree.

When no further imaging is needed. Classic mechanical instability with clear giving way, a normal weight-bearing series, a neutral hindfoot and no rest pain. Treat with 8-12 weeks of proprioceptive and peroneal strengthening rehabilitation first, and image only if rehabilitation fails or pain features emerge.

Related pages, following the five tender points. Anterolateral gutter: Lateral Ankle Sprains is the injury this all follows, Lateral Ankle Instability is the ligament diagnosis, and Osteochondral Lesion of the Talus the intra-articular lesion found in nearly a quarter of operated instability ankles. Retrofibular: Peroneal Tendon Disorders, Peroneal Tendon Tears and Peroneal Tendon Subluxation cover the commonest single finding at operation. Sinus tarsi: Sinus Tarsi Syndrome, Anterior Process of Calcaneus Fractures and Subtalar Arthritis. Below the fibular tip: Lateral Process of Talus Fractures is the snowboarder's fracture that needs CT. Posterolateral: Os Trigonum and Posterior Ankle Impingement. Also on the differential: Tarsal Coalition in the stiff adolescent hindfoot, Syndesmotic Instability for the high sprain, Jones Fractures and Fifth Metatarsal Stress Fractures for pain that is really in the foot, Superficial Peroneal Nerve Anatomy for neuropathic lateral pain, and Cavovarus Foot with Charcot-Marie-Tooth Disease for the hindfoot varus that must be corrected before any ligament reconstruction.

The must-not-miss diagnoses head the table because each presents as the sprain it was first called.

The joint surface. MRI localises an osteochondral lesion on the nine-zone Raikin grid of the talar dome, and arthroscopy confirms the chondral damage and stages it.

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The gutter and the anterior joint. The lesion behind anterolateral pain without instability is soft tissue: a meniscoid lesion, a hypertrophied Bassett's ligament or an intra-articular plica draped across the anterior ankle. Lateral, central and medial tibial osteophytes are responsible for anterior impingement.

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The ligament. Chronic ATFL deficiency looks like absent fibres at arthroscopy and an irregular, thickened remnant on MRI; ultrasound shows the full-thickness defect dynamically.

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The tendons behind the fibula. The peroneal lesions are a longitudinal split of brevis, tenosynovitis, and subluxation from a deficient superior peroneal retinaculum. A split brevis wraps around longus, which is the C-shape on the axial image.

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The stiff adolescent hindfoot. On the lateral radiograph a talocalcaneal coalition shows as the C-sign, a continuous curved density from the medial talar dome to the sustentaculum, and as a dorsal talar beak, which is chronic traction at the talonavicular capsule and an indirect clue to restricted hindfoot motion. When the radiographs understate the bridge, MRI shows the fibrous component of a mixed coalition and explains the pain.

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Was there a real injury, and how old is the patient? Establish whether a genuine inversion injury occurred, take the age, and ask directly about night and rest pain. No injury and age under 16 with a stiff hindfoot means coalition; no injury and bilateral symptoms means inflammatory arthropathy or a systemic cause; a clear inversion injury opens the post-traumatic list. Night and rest pain at any age means tumour or infection until excluded, and is not explained by instability alone.

Pain, giving way, or both? Make the patient separate the two complaints explicitly, because they will otherwise report both as "my ankle is bad". Pure giving way with minimal pain is mechanical instability, a ligament problem; pure pain with a stable ankle is impingement, an osteochondral lesion, peroneal pathology or an occult fracture. Both together means instability with an intra-articular lesion, and that changes the operation from stabilisation alone to stabilisation plus arthroscopy. Do not call it "just instability": instability and intra-articular pathology coexist, and up to a large proportion of ankles undergoing stabilisation have an associated chondral lesion, loose body or synovitis at arthroscopy.

Is the hindfoot aligned? Stand the patient and look from behind. A varus heel with a peek-a-boo sign means cavovarus, and a cavovarus foot with a plantarflexed first ray reproduces the sprain and blows out any ligament repair: uncorrected varus is the principal cause of a failed Broström. Do the Coleman block test, search for Charcot-Marie-Tooth disease, and plan a lateralising calcaneal osteotomy alongside any ligament work. Valgus with a stiff subtalar joint in an adolescent means coalition.

Does a targeted diagnostic injection settle it? Where imaging is equivocal, inject local anaesthetic under image guidance into the single structure most suspected, the sinus tarsi, the subtalar joint or the peroneal sheath, and reassess immediately. A well-placed block localises the pain generator and predicts response to surgery better than any scan. A negative block in the presence of a positive scan should stop the operation, not be explained away.