Extra-articular lateral hindfoot impingement syndrome is a non-traumatic cause of ankle impingement. This can include talocalcaneal, calcaneofibular (subfibular) or combined talocalcaneal-subfibular impingements.
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Clinical presentation
It presents as the sequela of a pathological tibialis posterior dysfunction, which can cause pes planus (flatfoot) and hindfoot valgus deformity. Healed intra-articular calcaneal fractures, neuropathic arthropathy, and inflammatory arthritides may also play a causative role.
Pathology
Impingement results from abnormal contact laterally as the valgus deformity results in sinus tarsi narrowing, which it does normally during eversion (although to a lesser degree in normal individuals) 3. Alternatively, there may be a subluxation of the subtalar joint resulting in impingement between the calcaneum and the fibula 4.
In cases of sinus tarsi narrowing, calcaneofibular impingement is unlikely to occur without sinus tarsi impingement. Thus, it is thought that impingement occurs laterally first through the sinus tarsi and then progresses to the calcaneofibular interval 3.
In cases of trauma and calcaneal fractures that have malunited, there may be lateral calcaneal wall blow-out with widening of the heel 4.
Radiographic features
MRI
Hindfoot valgus (often defined as a tibiocalcaneal angle >11º) with one or both of the following 5:
talocalcaneal impingement: high STIR signal at opposing non-articular talar and calcaneal surfaces +/- sclerosis/cysts with high signal in the lateral sinus tarsi
calcaneofibular impingement: high STIR signal at opposing non-articular fibular and calcaneal surfaces +/- sclerosis/cysts with high signal in the calcaneofibular interval (i.e. subfibular soft tissues)
Treatment and prognosis
Treatment may be non-operative or operative. Operative treatment is reserved for patients that fail non-operative treatment. The aim of operative treatment is to correct the hindfoot valgus and includes 4:
medialising calcaneal osteotomy
subtalar arthrodesis
combination of the two
additionally, removal of any subfibular or superolateral calcaneal bone causing impingement