Cadaveric flatfoot model: ligament attenuation and Achilles tendon overpull.

Area of Science:

• Orthopedics
• Biomechanics
• Anatomy

Background:

• Flatfoot deformity involves loss of the medial longitudinal arch, forefoot abduction, hindfoot eversion, and Achilles tendon contracture.
• Developing accurate cadaveric models is crucial for understanding pes planus biomechanics.

Purpose of the Study:

• To validate a cadaveric flatfoot model using selective ligament attenuation.
• To investigate the association between Achilles tendon overpull and pes planus severity.

Main Methods:

• Created a cadaveric flatfoot model by attenuating key ligaments and applying cyclic axial loading.
• Measured three-dimensional bone orientations in unloaded, loaded, and Achilles tendon overpull conditions.

Main Results:

• The validated model demonstrated significant changes consistent with pes planus: first metatarsal dorsiflexion/abduction, navicular abduction, calcaneal eversion, and talar plantarflexion/adduction.
• Achilles tendon overpull exacerbated the deformity, notably increasing arch depression and forefoot abduction.

Conclusions:

• Selective ligament attenuation combined with axial loading effectively replicates the complex biomechanics of flatfoot deformity in a cadaveric model.
• Simulated Achilles tendon contracture significantly worsens flatfoot severity, highlighting its clinical relevance.