Arthrodesis with external fixation in the unstable or misaligned Charcot ankle in patients with diabetes mellitus

The unstable or misaligned Charcot ankle with or without chronic foot ulceration is a major clinical challenge. When it cannot be accommodated with an ankle foot orthosis, surgical treatment is indicated in order to avoid leg amputation. This requires extensive soft tissue release and bony resection to realign the foot and arthrodesis with internal or external fixation. The guidance in the literature favors internal fixation. This article reports results with external fixation in 11 patients (12 feet) over a period of 12 years. External fixation was chosen as the surgical option because of the presence of foot ulcers with the attendent risk of infection. There were 7 tibio-talar and 5 tibio-calcaneal fusions. Compression was applied for 6 weeks with an external frame according to Charnley, followed by 6 weeks with total-contact cast. Weight bearing with a rigid leather brace was allowed after 12 weeks. In one case, transtibial amputation was required due to loosening of the distal pins from osteopenic disintegrating bone. In 11 cases (92%), the foot was successfully realigned and independent walking with a brace retained during the follow-up of median 48 months (10-102 months). Bony union took place in 5 out of 7 cases with tibio-talar fusion and in 1 out of 5 with tibio-calcaneal fusion. The functional result in cases with fibrous union was, however, satisfactory. Although meaningful comparisons of series are difficult to conduct and interpret from, the limb salvage rate was similar to results with internal fixation. The authors consider the results to be encouraging and to be used to develop a higher level of evidence.