An ex vivo sequential ligament transection model of flatfoot

Area of Science:

• Biomechanics
• Orthopedics
• Foot and Ankle Surgery

Background:

• Progressive collapsing foot deformity mechanisms are not fully understood.
• Existing cadaveric models limit assessment of early, individual ligament contributions to load distribution.
• Serial ligament transection can elucidate early changes in foot pressure distribution.

Purpose of the Study:

• To investigate the role of specific ligaments in maintaining plantar load distribution during the development of foot deformities.
• To identify critical ligamentous structures involved in early stages of progressive collapsing foot deformity.

Main Methods:

• Utilized a custom loading system for axial and tendon loading of foot specimens.
• Recorded plantar pressure data for forefoot and hindfoot before and after sequential ligament transections.
• Performed six serial ligament complex transections to simulate progressive deformity.

Main Results:

• Transection of the plantar fascia and short/long plantar ligaments did not significantly alter load distribution.
• Division of the spring ligament caused hindfoot load redistribution, indicating valgus angulation.
• Complete flatfoot deformity required transection of all six ligament complexes to shift the center of pressure anteriorly.

Conclusions:

• The plantar fascia and short/long plantar ligaments are not essential for maintaining plantar load distribution.
• The spring ligament, in combination with the plantar fascia and short/long plantar ligaments, is critical for preventing peritalar subluxation.
• Minor load distribution changes occur in later stages of flatfoot deformity compared to the initial loss of the spring ligament.