Proximal shortening lesser metatarsal osteotomy: a mathematical-geometric basis

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Surgical Anatomy

Background:

• Iatrogenic complications from lesser metatarsal osteotomy present a surgical challenge.
• Restoring the lesser metatarsal parabola requires precise bone resection.

Purpose of the Study:

• To develop a geometric and mathematical formula for proximal shortening lesser metatarsal osteotomy.
• To aid surgeons in determining the optimal amount of bone resection for deformity correction.

Main Methods:

• Part I: Performed osteotomies on 15 cadaver lesser metatarsals, placed radio-opaque markers, and used radiography and computer graphing to analyze geometric changes.
• Part II: Verified the derived formulas on 15 sawbone metatarsals using incremental bone removal.
• Part III: Assessed formula reproducibility for height changes across varying metatarsal declinations in sawbone models.

Main Results:

• Developed formulas: Length change = Bone removed *0.95; Height change = Bone removed *0.54; Dorsiflexion change = Bone removed *0.44 mm/deg.
• Formulas demonstrated statistical validity for length, height, and dorsiflexion with 95% confidence.
• Reproducible results were achieved across different metatarsal declinations.

Conclusions:

• The study provides validated, reproducible formulas for proximal shortening lesser metatarsal osteotomy.
• These formulas can assist foot and ankle surgeons in precisely correcting deformities.
• The findings offer a valuable tool for managing iatrogenic complications of metatarsal osteotomies.