Purpose of the study: When treating flatfoot, the objective of subtalar arthrodesis is to reestablish appropriate relations between the talus and the calcaeum by implanting a spacer. The purpose of this study was to evaluate the use of an expansion screw placed in the tarsal sinus and to assess the outcome.

Material and methods: Thirty patients with reducible symptomatic flatfoot participated in the study. There were 28 men and 2 women. Surgery was proposed because of pain-related functional disability and failure of orthopedic treatment. Mean age at surgery was 21 years. The Djian-Annonier angle was 134°. The patients were reviewed retrospectively. The Kitaoka function score was noted.

Results: Mean follow-up was four years. None of the patients wore orthopedic shoes. Degenerative joint remodeling was not observed. The overall outcome was: very good (n=20), good (n=4), fair (n=2), poor (n=4).

Discussion: Arthrorisis using a spacer positioned in the tarsal sinus is a technically simple procedure enabling significant podoscopic correction of flatfoot which persists.

Conclusion: This simple technique enables satisfactory anatomic and functional results.