The Effect of Alterations of Calcaneal Height on the Ankle and Chopart’s Joint: A Cadaveric Study

Abstract

Fracture of the calcaneum is common, and the majority are displaced intra-articular fracture patterns. Over the last three decades there have been considerable advances in the management of this injury. Open reduction and internal fixation is an accepted treatment for displaced fractures, and percutaneous techniques are now emerging. However, surgical treatment remains controversial, and many fractures are still managed conservatively. Non-operative management of displaced fractures may result in a disabling fracture malunion. The malunion is often a widened and depressed calcaneum, with subtalar joint disruption. This creates a five time risk of requiring a subtalar arthrodesis within 5 years of injury. Affected patients are frequently men of working age, with potentially significant socioeconomic consequences. Bone Block Distraction Arthrodesis (BBDA) is a technique used for the management of calcaneal malunion. In BBDA, restoration of the talocalcaneal height has been described for reconstitution of the talocalcaneal relationship. By restoring the talo calcaneal height, anterior tibio-talar impingement is relieved and ankle dorsiflexion range improved. In our clinical experience we have also noted a rotational change in the talus with loss of calcaneal height. We hypothesised that depression of the calcaneal articular surface causes extension of the talus in the sagittal plane, causing anterior tibiotalar impingement, but additionally, incongruity of the talonavicular joint. This hypothesis is important in surgical correction, because classical BBDA may need to be modified to include reversal of the abnormal talar rotation to restore Chopart’s joint alignment. Appropriate restoration of the subtalar joint surface and talonavicular joint anatomy is likely to reduce the need for arthrodesis, and improve function. This cadaveric study is a proof of concept aiming to demonstrate changes in talar inclination and talo-navicular joint alignment following loss of calcaneum height, as is the case in calcaneum malunion, and then following restoration of the calcaneal height as in BBDA.