Coronal Plane Alignment of the Medial Column in Isolated Hallux Valgus, Isolated Flatfoot, and Combined Hallux Valgus-Flatfoot.

Background: To provide improved treatment for hallux valgus (HV), we sought to understand more about the pathophysiologic connection between flatfoot deformity and HV by comparing coronal plane alignment of the medial column of the foot for patients with isolated HV, isolated flatfoot, and combined HV-flatfoot vs controls.

Methods: This study retrospectively assessed a consecutive series of 33 patients with combined symptomatic and radiographic HV and flatfoot, 33 isolated symptomatic HV, 33 isolated symptomatic flatfoot, and 33 controls. The medial column alignment was assessed in the coronal plane using 3-dimensional weightbearing computed tomography (WBCT); rotation was measured for the navicular, medial cuneiform, and first metatarsal (M1). The position of the first naviculocuneiform (NC) and tarsometatarsal (TMT) joints were determined.

Results: M1 intrinsic pronation was significantly greater in patients with combined HV-flatfoot (-12.0 ± 7.0 degrees;  < .001), isolated HV (-12.1 ± 6.6 degrees;  < .001), and isolated flatfoot (-11.8 ± 8.5 degrees;  < .001), compared with control patients (-19.4 ± 6.7 degrees). TMT was significantly more pronated in patients with combined HV-flatfoot (30.9 ± 6.2 degrees) compared with isolated flatfoot (25.3 ± 9.3 degrees;  = .007), and control (25.9 ± 5.2 degrees;  = .005), as it was in patients with isolated HV (33.2 ± 8.2 degrees) compared with isolated flatfoot ( < .001), and control ( < .001). NC was significantly more supinated in patients with combined HV-flatfoot (-23.7 ± 3.9 degrees) compared to isolated flatfoot (-18.0 ± 9.8 degrees;  = .001), and control (-18.0 ± 4.5 degrees;  < .001), as it was for patients with isolated HV (-24.8 ± 7.1 degrees) compared with isolated flatfoot ( = .003), and control ( < .001).

Conclusion: In our study, we found that patients with isolated HV, isolated flatfoot, or combined HV-flatfoot presented a similar increase in M1 intrinsic pronation of approximately 7.5 degrees, compared with controls. Moreover, patients with isolated HV or combined HV-flatfoot had greater TMT pronation and NC supination, compared with patients with isolated flatfoot and controls.