Plantar measurements to determine success of surgical correction of Stage IIb adult acquired flatfoot deformity

Abstract

Adult acquired flatfoot deformity is a degenerative disease causing medial arch dysfunction. Surgical correction has typically involved tendon reconstruction with calcaneal osteotomy; however, the postoperative changes have not been fully characterized. The present study assessed the success of surgical correction of Stage IIb adult acquired flatfoot deformity through changes in plantar pressures and patient-generated outcome scores. With Institutional Review Board approval, 6 participants were evaluated before and after surgery using pedobarography, the Foot and Ankle Outcome Score, and the Medical Outcomes Study 36-item short-form questionnaire. The plantar pressures were recorded using a TekScan HRMat(®) during walking and in a 1- and 2-foot stance. The resulting contour maps were segmented into 9 regions, with the peak pressure, normalized force, and arch index calculated. Surgical effects were analyzed using paired t tests. Postoperatively, the Foot and Ankle Outcome Score and Medical Outcomes Study 36-item short-form questionnaire scores increased significantly from 180 ± 78 to 360 ± 136 (p < .03) and 47 ± 18 to 71 ± 19 (p = .06), respectively. During the 2-foot stance, the normalized force had increased significantly in the lateral midfoot (p < .03), although no significant differences were found in peak pressures. No significant differences were observed in the 1-foot stance. During walking, the normalized force increased significantly in the lateral mid- and forefoot (p < .05). The peak pressure increased significantly in the lateral forefoot (p < .01). The arch index values demonstrated no significant changes. The increased questionnaire scores indicated that surgical correction improved the self-perceived health of the participants. Lateral shifts in the peak pressure and normalized force suggest that forefoot and midfoot loading is altered postoperatively, consistent with the goal of offloading the dysfunctional arch. Thus, the present study has demonstrated that surgical treatment of adult acquired flatfoot deformity can be accurately assessed using patient-reported outcome measures and plantar pressures.

Keywords: Foot and Ankle Outcome Score; Short Form 36 item; pedobarography; posterior tibial tendon insufficiency; valgus tilting.