Subtalar Fusion Preparation: What Are We Really Doing? A Cadaver Study

Area of Science:

• Orthopedic Surgery
• Anatomy
• Surgical Techniques

Background:

• Subtalar arthrodesis aims to fuse the talus and calcaneus to eliminate painful motion.
• The open, lateral sinus tarsi approach is a common surgical technique for this procedure.

Purpose of the Study:

• To quantify the maximum joint surface area denuded of cartilage and subchondral bone using the lateral sinus tarsi approach in a cadaveric model.
• To identify specific joint facets that are most challenging to prepare via this approach.

Main Methods:

• Nine fresh frozen human cadaver specimens were utilized.
• A lateral incision was made to access the subtalar joint.
• Cartilage removal was performed on the anterior, middle, and posterior facets of the talus and calcaneus.
• ImageJ software was used to measure the remaining undenuded cartilage surface area.

Main Results:

• No specimen achieved 100% cartilage denudation across all six measured surfaces.
• The middle facet of the talus (average 18.66% unprepared) and calcaneus (average 14.51% unprepared) had the largest remaining unprepared areas.
• The average total unprepared joint surface area across all specimens was 8.67%.

Conclusions:

• The lateral sinus tarsi approach generally provides adequate preparation of the subtalar joint for arthrodesis.
• The percentage of unprepared joint surface can range from approximately 2% to 18%.
• Clinical studies are recommended to correlate this preparation adequacy with subtalar fusion rates.