title: Observed changes in radiographic measurements of the first ray after frontal and transverse plane rotation of the hallux: does the hallux drive the metatarsal in a bunion deformity?
abstract: It is well known that the pathologic positions of the hallux and the first metatarsal in a bunion deformity are multiplanar. It is not universally understood whether the pathologic changes in the hallux or first metatarsal drive the deformity. We have observed that frontal plane rotation of the hallux can result in concurrent positional changes proximally in the first metatarsal in hallux abducto valgus. In the present study, we observed the changes in common radiographic measurements used to evaluate a bunion deformity in 5 fresh frozen cadaveric limbs. We measured the tibial sesamoid position, 1-2 intermetatarsal angle, and first metatarsal cuneiform angle on anteroposterior radiographs after frontal and transverse plane manipulation of the hallux. When the hallux was moved into an abducted and valgus position, a statistically significant increase was found in the tibial sesamoid position (p = .016). However, we did not observe a significant increase in the intermetatarsal angle (p = .070) or medial cuneiform angle (p = .309). When the hallux was manipulated into an adducted and varus position, a statistically significant decrease in the intermetatarsal angle (p = .02) and a decrease in the tibial sesamoid position (p = .016) was seen, with no significant change in the medial cuneiform angle (p = .360). We also observed a consistent rounding of the lateral aspect of the first metatarsal head and an increase in the concavity of the lateral metatarsal shaft, with valgus rotation of the hallux. From these observations, it is possible that the hallux could drive the proximal changes in the first ray that lead to metatarsus primus adducto valgus deformity.
authors.affiliation: Foot and Ankle Division, UnityPoint Clinic, and Adjunct Professor, Des Moines University College of Podiatric Medicine and Surgery, Fort Dodge, IA. Electronic address: daytonp@me.com.
authors.forename: Paul
authors.initials: P
authors.lastname: Dayton
authors.affiliation: Assistant Professor, Des Moines University College of Podiatric Medicine and Surgery, Fort Dodge, IA.
authors.forename: Mindi
authors.initials: M
authors.lastname: Feilmeier
authors.affiliation: Podiatric Medical Student, Des Moines University College of Podiatric Medicine and Surgery, Des Moines, IA.
authors.forename: Merrell
authors.initials: M
authors.lastname: Kauwe
authors.affiliation: Podiatric Medical Student, Des Moines University College of Podiatric Medicine and Surgery, Des Moines, IA.
authors.forename: Colby
authors.initials: C
authors.lastname: Holmes
authors.affiliation: Podiatric Medical Student, Des Moines University College of Podiatric Medicine and Surgery, Des Moines, IA.
authors.forename: Austin
authors.initials: A
authors.lastname: McArdle
authors.affiliation: Second Year Resident, Podiatric Medicine and Surgery Residency, Foot and Ankle Division, UnityPoint Health, Fort Dodge, IA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Coleman
mesh_terms: D000368:Aged; D001837:Body Weights and Measures; D002102:Cadaver; D005260:Female; D005528:Foot / Q000000981:diagnostic imaging; D006214:Hallux / Q000000981:diagnostic imaging* / Q000601:surgery; D006215:Hallux Valgus / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D008297:Male; D008682:Metatarsal Bones / Q000000981:diagnostic imaging* / Q000601:surgery; D011859:Radiography; D012399:Rotation
keywords: etiology; fresh frozen cadaver; hallux abducto valgus; metatarsus primus adducto valgus; tibial sesamoid position