Geometric analysis of the Weil osteotomy

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Foot and Ankle Surgery

Background:

• Weil osteotomy is effective for metatarsalgia and intractable plantar keratosis.
• Plantar inclination of the metatarsal is a key factor in osteotomy outcomes but lacks detailed study.

Purpose of the Study:

• To investigate the impact of metatarsal plantar inclination on Weil osteotomy geometry.
• To determine the effect of saw blade thickness on capital fragment displacement.

Main Methods:

• Analysis of five fresh or fresh-frozen cadaver specimens.
• Modeling the geometry of the Weil osteotomy based on specimen data.
• Evaluation of thick saw blade effects on the osteotomy.

Main Results:

• Second metatarsal inclination averaged 24.6 degrees (range 19-31).
• Plantar displacement of the capital fragment depends on osteotomy angle and metatarsal inclination.
• A 5mm proximal displacement with a 25-degree osteotomy resulted in plantar displacement at 19-degree inclination and dorsal displacement at 25 degrees or more.

Conclusions:

• Thick saw blades can offset plantar displacement of the capital segment in Weil osteotomies.
• A 1mm saw blade is recommended for most cases; a 2mm blade for >5mm shortening or <19-degree inclination.
• Consideration of thicker saw blades is advised for treating plantar keratosis.