Relationship between forefoot structure, including the transverse arch, and forefoot pain in patients with hallux valgus

[Purpose] Hallux valgus occurs in the forefoot where the transverse arch is located and may be a factor involved in forefoot pain. The relationship between forefoot pain and forefoot structure is unknown. This study aimed to analyze the relationship between forefoot pain and the transverse arch in patients with hallux valgus. [Participants and Methods] In this study, 122 (197 feet) adult females (46 to 86 years old) with hallux valgus were studied. By using questionnaires, the females were divided into two groups depending on whether or not they had forefoot pain (a group with forefoot pain [P group] and a group without forefoot pain [NP group]). The hallux valgus angle was measured using a goniometer, and the transverse arch was measured using a weight-bearing plantar ultrasonography imaging device. The transverse arch measurements included the transverse arch height and length. [Results] Only the transverse arch length, even after adjustment, was significantly greater in the P group. No significant difference was found between the hallux valgus angle and the transverse arch height. [Conclusion] The greater transverse arch length in the P group was possibly due to the collapsing transverse arch support muscles. Increased width probably caused inadequate impact absorption which in turn led to forefoot pain.