Properties and Function of the Flexor Hallucis Capsularis Interphalangeus Tendon

Area of Science:

• Anatomy
• Biomechanics
• Histology

Background:

• The plantar plates of the forefoot are crucial for foot arch support during gait.
• These plates serve as the main attachment for the plantar aponeurosis and are key to the windlass mechanism.
• A previously described but unresearched structure, the flexor hallucis capsularis interphalangeus (FHCI), was noted in the hallux.

Purpose of the Study:

• To further investigate the flexor hallucis capsularis interphalangeus (FHCI).
• To identify the characteristics of the FHCI.
• To understand the biomechanical role of the FHCI in foot function.

Main Methods:

• Dissection of eight cadaveric hallux specimens.
• Histological examination using polarized and non-polarized light microscopy.
• Micrometer testing to evaluate the tensile properties of the FHCI.

Main Results:

• Histological analysis revealed features consistent with tendon tissue.
• Mechanical testing indicated that the FHCI possesses tensile strength and stiffness.
• Variations in cross-sectional area, ultimate tensile strength, and stiffness were observed among specimens.

Conclusions:

• The FHCI tendon, due to its location and properties, may limit dorsiflexion of the first MTP joint.
• The FHCI tendon could be clinically relevant in pathologies affecting the first and second MTP joints.
• Further research is warranted to fully elucidate the role of the FHCI in foot biomechanics and clinical conditions.