Coronal Hindfoot Alignment in Midfoot Charcot Neuroarthropathy.

Coronal plane hindfoot malalignment produces abnormal compensatory forces within the midfoot and forefoot. The primary aim of this study is to compare radiographic hindfoot alignment in patients with a midfoot Charcot event, and identify patterns associated with breakdown. A retrospective review of 43 patients (48 limbs) with midfoot Charcot neuroarthropathy were compared between the coronal hindfoot alignments and Charcot joint involvement. Coronal hindfoot alignment was classified as neutral (n = 15), valgus (n = 16), and varus (n = 17) utilizing the Saltzman hindfoot alignment radiograph. Charcot joint breakdown was classified as isolated tarsometatarsal joint (n = 8), combination of tarsometatarsal and naviculocuneiform joints (n = 22), and midtarsal joints including talonavicular and calcaneocuboid joints (n = 18). Patients exhibiting varus hindfoot alignment had 5.8 times greater risk of breakdown at the tarsometatarsal and naviculocuneiform joints (odds ratio 5.8, 95% confidence interval 1.7-22.9, p < .01). Hindfoot varus induces external rotation of the talus, resulting in compensation through the naviculocuneiform and tarsometatarsal joint, which correlates with our findings of a 6-fold increase in naviculocuneiform and tarsometatarsal joint collapse. Patients exhibiting valgus hindfoot alignment had 27 times greater risk of breakdown at the midtarsal joint (odds ratio 27.0; 95% confidence interval 5.6-207.0, p < .01). Hindfoot valgus induces internal rotation of the talonavicular joint, which correlates with our findings of a 27-fold increase in midtarsal joint breakdown. Varus and valgus hindfoot alignment are associated with different midfoot injury patterns, which may have implications in surgical management and allow for focused surveillance in neuropathic patients presenting with early-stage clinical findings consistent with Charcot neuroarthropathy.