High Incidence of spring ligament failure in ankle fractures with complete deltoid ruptures: a previously missed entity leading rapid destabilisation of the first ray and symptomatic adult flat foot

A.M.E.-S. Ali, B. Kiliyanpilakkil, C. Pasapula

Introduction: Injury to the deltoid ligament complex is an easy to diagnose and an accepted frequent consequence following ankle fractures involving the medial foot. Injury to the spring ligament however is not easily diagnosed and the incidence following ankle fractures with deltoid ligament rupture is unknown.

Methods: We present a series of 15 patients who were followed up at 28.5 (+/-14) months post ankle fracture involving deltoid ligament rupture as diagnosed on radiographs.

Results: We found that 100% of patients had spring ligament rupture as diagnosed with a lateral translation score of >20mm (p< 0.001). These patients were also found to have tarsometatarsal (TMT) instability, an established complication of spring ligament rupture, implicated in the development of adult acquired pes planus (p< 0.001). We found that the degree of spring ligament strain correlated with the degree of TMT instability (correlation coefficient +0.62).

Conclusions: This study demonstrates an unrecognised phenomenon in the literature. The rupture of the spring ligament at the time of injury is not recognised and, as we demonstrate with TMT instability, leads to rapid failure of the first ray. This finding would indicate that a new facet of treatment must be recognised and implemented in the long term management of ankle fractures as this medial column instability must be recognised.