Background: Progressive collapsing foot deformity (PCFD) and hallux valgus (HV) are complex 3-dimensional deformities
of the foot. This study aimed to investigate structural and alignment differences between PCFD with and without HV using
weightbearing computed tomography.
Methods: Patients with PCFD aged 18 years or older who underwent weightbearing computed tomography were
consecutively enrolled. Standard 2-dimensional PCFD and HV parameters were assessed semiautomatically. Foot and ankle
offset, forefoot arch angle, and pronation of the medial column bones in the coronal plane, with the ground as a reference,
were manually measured. Additionally, the angles from the inferior aspect of subtalar posterior facet of the talus to the
ground (subtalar horizontal angle), from the inferior (posterior facet) to superior facets of the talus (infratalar-supratalar
angle), and from the inferior (posterior facet) of the talus to the superior facet of the calcaneus (infratalar-supracalcaneal
angle) were examined. HV deformity was defined by an HV angle of ≥15 degrees.
Results: Among 72 feet (58 patients) studied, 33 displayed HV, whereas 39 did not. In the coronal plane, the PCFD
with HV group showed a higher infratalar-supratalar angle and greater pronation at the first tarsometatarsal joint, first
metatarsal bone, and head. The PCFD with HV group also exhibited greater naviculocuneiform joint supination. Generalized
estimating equation logistic regression analysis revealed significant associations of HV deformity with the intrinsic rotation
of the first metatarsal bone (P < .001), infratalar-supratalar angle (P = .004), and rotation of the first tarsometatarsal joint
(P < .001).
Conclusion: This study confirmed significant structural and alignment differences between PCFD with and without
HV. Notably, the infratalar-supratalar angle, rotation of the first tarsometatarsal joint, and intrinsic rotation of the first
metatarsal bone were associated with HV deformity.
Level of Evidence: Level III, retrospective comparative study.
