[The acquired buckling-flatfoot. A foot deformity due to obesity?]

Flatfoot deformity is characterized by a multiplanar hindfoot malalignment. Although the etiology remains unclear, the deformity is mainly attributed to ligamentous laxity and dysfunction of the posterior tibial tendon. Obesity is thought to be a risk factor that additionally impairs hindfoot stability. Performing a retrospective clinical and radiological study, we compared two groups, each with 75 patients. One group included patients with a flatfoot deformity stage 2, while the other group showed no hindfoot malalignment. Reviewing the weight and calculating the body mass index revealed significantly increased values for those patients with flatfoot deformity (P=0.034 and P>0.001, respectively). This correlation should be considered during the decision-making process on surgical strategies. In obese patients with flatfoot deformity, stage 2 soft tissue reconstruction and hindfoot osteotomies should be combined with hindfoot arthrodeses, i.e. subtalar fusion, to maintain sufficient and durable stability.