Three-dimensional morphological variations in the calcaneus and talus in relation to the hallux valgus angle

Area of Science:

• Orthopedics
• Podiatry
• Biomechanics

Background:

• Hallux valgus (HV) is a common foot deformity.
• Understanding the morphological associations of the calcaneus and talus with HV is crucial for treatment.
• Previous studies have not fully elucidated the specific hindfoot bone morphology linked to varying hallux valgus angles (HVA).

Purpose of the Study:

• To clarify the morphological patterns of the calcaneus and talus associated with hallux valgus angle (HVA).
• To quantify differences in hindfoot bone morphology between left and right sides in HV patients with bilateral HVA differences.

Main Methods:

• Utilized 3D computed tomography scans of 32 feet from 16 HV patients with significant bilateral HVA differences.
• Generated 3D surface models of the calcaneus and talus.
• Analyzed shape variations using principal component analysis (PCA) on numerous landmarks, comparing PC scores between sides with small and large HVA.

Main Results:

• A larger HVA was associated with a slender calcaneal tuberosity, a medially oriented posterior articular surface, and narrower, more concave anterior-middle articular surfaces.
• The talus in larger HVA feet showed a more medially oriented talar head and a more anteriorly protruded lateral talar head region.
• These findings highlight distinct calcaneal and talar morphologies correlating with HV severity.

Conclusions:

• Morphological patterns of the calcaneus facilitate hindfoot rotation in the everting direction, potentially contributing to HV.
• Talar morphology associated with larger HVA may induce greater internal rotation of the first metatarsal.
• These calcaneal and talar structural patterns are likely contributing factors to hallux valgus development.