Three-dimensional architecture of the great toe muscles: functional implications in hallux valgus

Objectives: Imbalance of great toe musculature has been identified as a factor in the development of hallux valgus. The musculoaponeurotic architecture, an important determinant of function, has not been investigated volumetrically in the great toe musculature. The purpose of this study was to reconstruct the abductor halluces (ABDH), adductor halluces (ADH), flexor hallucis brevis medial (FHBM) and lateral (FHBL) heads volumetrically and to quantify and compare their architectural parameters and functional characteristics. Methods: Ten formalin-embalmed specimens were dissected, digitized and modelled (Autodesk Maya®). Fiber bundle length (FBL) and physiological cross-sectional area (PCSA) of the muscles were compared using descriptive and parametric statistics. Results: The spatial arrangement of aponeuroses (AP) / fiber bundles (FB) and architectural parameters varied throughout the volume of each muscle. The PCSA of the medial (ABDH/FHBM) and lateral (ADH/FHBL) musculature was similar; however, the medial musculature had significantly greater mean FBL. Conclusion: Each muscle had varying AP/FB arrangement. The similar PCSA of the medial and lateral musculature suggests that their relative force generating capabilities are balanced in asymptomatic individuals.