Foot Deformity in Patients With Ankylosing Spondylitis: Is It Associated With Functionality and Disease Activity?

Foot involvement affects mobility and functionality in patients with ankylosing spondylitis but it remains unknown if foot deformities in ankylosing spondylitis patients affect functionality, disease activity, and quality of life. The aim of this study was to evaluate in detail the presence of a relationship between radiologically detected foot deformities in ankylosing spondylitis patients and both clinical and electrophysiological findings. The cross-sectional study included 110 patients with ankylosing spondylitis who were diagnosed according to the Assessment in Spondyloarthritis International Society criteria and were followed in our hospital. Demographic and clinical data of all patients were recorded. Bilateral lateral foot x-rays and electrophysiology examinations were evaluated in all subjects. The arch in the dominant foot of the patients was classified in 3 groups as pes cavus, pes planus, or normal. The clinical outcomes, physical examination and electrophysiological findings were compared between the groups, and correlations were examined of the foot deformities with these parameters. Foot deformities were determined at a high rate (74.5%). These deformities affected foot pain, disability and quality of life. Pes cavus deformity was found to be associated with hip pain and enthesopathy. In the electrophysiological studies, the presence of pes planus was found to be associated with the findings of the tibial and sural nerve conduction studies, and the presence of pes cavus with the findings of the peroneal nerve conduction study. In conclusion, foot deformities may have an effect on the quality of life and functionality in ankylosing spondylitis patients.