Subtalar fusion with previous Ipsilateral Ankle Arthrodesis: an entity to look for

Y. Elhassan, A. Jamjoom, A. Lomax, N. Tellisi

¹Chapel Allerton, Leeds Teaching Hospital, Trauma ad Orthopaedics, Leeds, United Kingdom

Introduction: Isolated subtalar arthrodesis is a commonly performed procedure that produces a high fusion rate. It is suggested that the fusion rate of subtalar arthrodesis is negatively affected by the presence of pre-existing ipsilateral ankle (tibiotalar) arthrodesis, though the mechanism by which this occurs remains unclear.The aim of this study is to assess subtalar arthrodesis fusion rate in the presence of pre-existing ipsilateral ankle arthrodesis and to suggest alternative operative techniques to improve fusion rates.

Methods: We retrospectively studied electronic patient records and images who underwent primary isolated subtalar arthrodesis were identified between (2009-2019). Two groups, those with and without previous ipsilateral ankle arthrodesis were compared. Factors affecting fusion rate including body mass index (BMI), smoking status, and co-morbidities such as diabetes and rheumatoid arthritis were studied.

Results: A total of one hundred and thirty-three (n=133) primary isolated subtalar arthrodesis were identified between (2009-2019), amongst which twenty-one (n=21) had pre-existing ipsilateral ankle arthrodesis. Ten (n=10) recorded subtalar non-unions occurred in the pre-existing ankle arthrodesis group representing a non-union rate of 47.6%, as opposed to sixteen(n=16)  in the isolated subtalar fusion group without pre-existing ipsilateral ankle arthrodesis group representing a non-union rate of only 13.1% (P = .001). Age, Body mass index (BMI), smoking status, diabetes, and rheumatoid arthritis were found not to have a significant effect on these results.

Conclusion: Our results show a significantly higher non-union rate of isolated subtalar arthrodesis in the presence of pre-existing ipsilateral ankle arthrodesis. Further research is required to help in clarifying the mechanism by which this effect occurs and to study alternative operative techniques that might be required.

Click thumbnail below to view poster / thumbnail: