ABSTRACT: Type II posterior tibial tendon deficiency (PTTD) represents a wide spectrum of disease and may be treated with a variety of corrective surgical procedures. Recent reports suggest that treatment may vary based on severity of flexible flatfoot deformity. Mild flexible flatfoot may be corrected with combined flexor digitorum longus transfer and medializing calcaneal osteotomy, whereas additional measures may be needed to correct more severe flexible flatfoot. Subtalar arthroereisis is an adjunct procedure that holds promise for patients with both the mild and more severe variants. In milder presentations of type II PTTD, subtalar arthroereisis may aid in the correction of hindfoot deformity and protect soft tissue reconstruction. In more severe type II PTTD, subtalar arthroereisis may further normalize parameters undercorrected with the initial procedure. In this article, we describe the background and surgical technique for subtalar arthroereisis with a Maxwell-Brancheau titanium arthroereisis sinus tarsi implant (KMI, Carlsbad, CA) combined with flexor digitorum longus transfer and medializing calcaneal osteotomy for treatment of type II PTTD.