Medial arch strain after lateral column lengthening: an in vitro study

Area of Science:

• Orthopedic surgery
• Biomechanics
• Foot and ankle anatomy

Background:

• Posterior tibial tendon dysfunction (PTTD) and flatfoot deformity involve medial arch ligamentous failure.
• Lateral column lengthening is a surgical technique used to address these conditions, aiming to restore the arch.
• The biomechanical effects of lateral column lengthening on medial arch structures require further investigation.

Purpose of the Study:

• To evaluate the impact of lateral column lengthening on medial arch strain.
• To assess the effects of various fusions (subtalar, talonavicular, double, triple) on medial arch strain.

Main Methods:

• Utilized whole cadaver feet subjected to vertical loads in a plantigrade position.
• Monitored spring ligament length using liquid metal displacement gauges.
• Measured ligament length and change in length per unit of applied load.

Main Results:

• Lateral column lengthening did not change overall ligament length.
• Talonavicular, double, and triple arthrodeses decreased ligament length, suggesting protection.
• The change in ligament length per unit of load after lateral column lengthening was similar to the intact foot.

Conclusions:

• Lateral column lengthening appears to maintain spring ligament function during weightbearing without increasing strain.
• Arthrodesis procedures protect the medial arch by reducing strain on the spring ligament.
• Findings support the use of lateral column lengthening in managing PTTD and flatfoot deformity.