A New Classification for Ankle Arthrodesis When Using an External Fixator

We have classified ankle arthrodesis when using an external fixator into four types based on the deformity and defect. Each of the four types of technique have been evaluated retrospectively.

Thirty-three lower limb segments in 30 patients (average age 49 years) were treated by ankle arthrodesis using an external fixator in our institution. We classified the pre-treatment problems into four types and adjusted the surgical treatment accordingly: type I-no bone defect, no or mild deformity; type II-no bone defect, severe deformity; type III-bone defect with the possibility to shorten acutely after resection of the pathological focus; and type IV-bone defect but without the ability to shorten acutely after resection of the pathological focus. Type I problems were treated with curettage of ankle cartilage and bone graft with external fixation. Type II problems were treated with mobilisation using an external fixation after performing a type I ankle arthrodesis. Type III problems were treated with ankle arthrodesis using acute shortening and distraction. Type IV problems were treated with ankle arthrodesis using bone transport.

All patients had secure ankle fusion and were able to bear total weight in walking on completion of treatment. The mean external fixation period was 96 days in type I, 181 days in type II, 231 days with lengthening in type III and IV. The complications included re-fracture in three cases, deformity at the lengthening site in one, delayed union in one, and infection at fusion site in one.

We have strategized ankle arthrodesis procedures using an external fixator into four groups in order to align the surgical technique with the pre-treatment problem. Our classification can help decide the appropriate operative method when using an external fixator, especially for difficult cases.

Matsubara H, Watanabe K, Takata M, et al. A New Classification for Ankle Arthrodesis When Using an External Fixator. Strategies Trauma Limb Reconstr 2019;14(3):148-154.