Optimal Guidewire Starting Position for Medial Column Intramedullary Fixation

Area of Science:

• Orthopedic surgery
• Podiatric medicine
• Anatomy

Background:

• Medial column intramedullary fixation is crucial for Charcot reconstruction.
• Accurate guidewire placement is essential for optimal endosteal purchase.
• Current methods lack defined anatomical relationships for guidewire insertion into the first metatarsal.

Purpose of the Study:

• To identify the anatomical relationship between the first metatarsal's intramedullary canal center and its head and base.
• To provide data for improving guidewire placement accuracy in foot and ankle surgery.

Main Methods:

• Dissection and measurement of ten fresh-frozen human first metatarsals.
• Utilized digital calipers for linear measurements (length, width, height).
• Employed 3D printed gantry and image analysis software to determine canal center relative to metatarsal dimensions.

Main Results:

• The intramedullary canal's center was located at approximately 51% of the head's height and 67% of the base's height (from inferior cortex).
• The center was found at approximately 53% of the head's width and 53% of the base's width (from lateral cortex).
• Longer metatarsals showed a correlation with a more superior starting position at the base (r = 0.74; P = .02).

Conclusions:

• Optimal guidewire entry is slightly superior and medial to the first metatarsal head's center.
• The guidewire should be directed proximally towards the superior third of the metatarsal base.
• These anatomical findings can refine surgical techniques and guide instrument development for Charcot reconstruction.