The effect of the Cotton osteotomy on midfoot sag during reconstruction of adult acquired flatfoot deformity

G.F. Dall, A. Ayier, J. Shub, M.S. Myerson

Introduction: The purpose of this study was to elucidate the specific radiographic effects that the Cotton osteotomy confers when used in combination with other reconstructive procedures in the management of the flexible flat foot deformity.

Methods: Between 2002-2013, 198 Cotton osteotomies were retrospectively identified following IRB approval. 131 were excluded on the basis of ipsilateral mid/hindfoot arthrodesis, inadequate radiographs or being less than 18yrs old at time of surgery. Parameters including the articular surface angles of the hindfoot/forefoot, Meary's angle and a newly defined Medial Arch Sag Angle (MASA) were recorded. A matched group of patients who did not undergo a Cotton osteotomy but who underwent similar hindfoot reconstructive procedures served as historic controls.

Results: 67 Cotton osteotomies in 59 patients with a mean age of 45 years (range, 18-80) were evaluated. Concomitant procedures included combinations of tibialis posterior tendon (PTT) reconstruction, Evans lateral column lengthening, medial displacement calcaneal osteotomy (MDCO). In all patients who underwent a Cotton osteotomy, there were statistically significant improvements in the articular surface angles along the medial side of the foot (p < 0.05). Improvement in arch height was also found to be statistically significant (p < 0.05). In comparison to matched controls, the Cotton osteotomy did not improve Meary´s angle but provided an additional 11.21° of MASA correction (p < 0.05) when used in in conjunction with the Evans procedure and PTT reconstruction. A similar trend was seen with MDCO and PTT reconstruction.

Discussion: This study confirms the Cotton osteotomy is a powerful surgical adjunct in flatfoot reconstruction and quantifies the additional 11.21° of MASA correction it provides when the Cotton osteotomy is added to a calcaneal osteotomy and PTT reconstruction. This has relevance as an alternative for selection of a medial column stabilization procedure, which is joint sparing.