High incidence of spring ligament laxity in ankle fractures with complete deltoid ruptures and secondary first ray instability.

AIMS: To assess the incidence of spring ligament failure in patients who have complete deltoid ruptures. PATIENTS AND METHODS: The authors retrospectively analysed ankle fractures in our trauma database from January 2015 to January 2019. 61 patients who sustained ankle fractures with complete deltoid ligament ruptures based on an AP ankle radiographs with increased medial joint space were identified. 25 patients attended clinic for assessment. Of these, 5 were found to have gross planovalgus with pre-existing spring ligament laxity in the uninjured control foot and these were excluded from the analysis. 20 patients were assessed for spring ligament failure /laxity. For each patient, the uninjured foot was used as the control. RESULTS: The TMT instability score and the lateral translation score showed statistically significant increases in the injured compared to the uninjured foot. The ratio of increase in both TMT instability and lateral translation scores (strain) in the injured versus the uninjured foot was assessed. A strong correlation (+0.62 pearson correlation coefficient) was found between the two ratios. CONCLUSION: All 20 patients showed increased spring ligament laxity and 19 patients showed increased TMT instability. Our results show that with complete deltoid rupture, there is likely greater disruption of the medial ligamentous structures of the foot than previously recognised. The degree of increase in the spring ligament strain also correlates with the degree of strain at the plantar TMT joint ligaments, and thus first ray instability. This finding has significant implications for the long-term assessment and management of ankle fractures involving complete deltoid disruption. Early intervention with orthotics in this cohort may prevent progressive destabilisation of the midfoot and the first ray. This evolving understanding may lead to the prospect of earlier surgical intervention to reconstitute the integrity of the spring ligament and protect the foot progressing to stage 2 AAFD.

Plantar fasciitis: Talonavicular instability/spring ligament failure as the driving force behind its histological pathogenesis.

The aetiology of plantar fasciitis (PF) remains uncertain and to date, it is not known if there is an association with spring ligament laxity. In this study, 28 patients with unilateral plantar fasciitis were evaluated. A digital Klaumeter was used to assess first ray for instability and lateral plane translation was used as a measure of spring ligament laxity in the affected vs unaffected foot (internal control). Retromalleolar tenderness as a sign of a reactive tibialis posterior tendon was also assessed. The mean lateral translation score for symptomatic feet was 67.2 (95% CI [63.26-71.14]), compared to asymptomatic feet mean of 33.0 (95% CI [27.35-38.65] p < 0.05). The mean TMT instability score for symptomatic feet was 11.3 (95% CI [10.29-12.3]), compared to the asymptomatic feet mean of 5.9 (95% CI [4.49-7.31] p < 0.05). 100% of symptomatic feet had a retromalleolar tenderness over the tibialis posterior compared to 14% of asymptomatic feet. This is the first study to demonstrate a statistically significant increase in spring ligament strain in feet affected with PF using internal controls. The study postulates that tensile overload at the medial plantar fascia develops secondary to spring ligament failure regardless of foot shape. Furthermore, this condition can be regarded as an early warning sign of adult acquired flat foot disorder (AAFD). Future treatments for PF should not further destabilise the medial arch. This understanding may allow development of new treatment strategies in restoring spring ligament integrity to offload the plantar fascia strain.