Optimization of portal placement for endoscopic calcaneoplasty.

Purpose: The purpose of our study was to determine an anatomic landmark to help locate portals in endoscopic calcaneoplasty.

Methods: The device for optimal portal placement (DOPP) was developed to measure the distance from the distal fibula tip to the calcaneus (DFC) in 28 volunteers to determine the location of the posterosuperior calcaneal border in relation to this line.

Results: The DOPP showed an interobserver reliability of 0.99 (95% confidence interval, 0.97 to 0.99). We found that portals should be placed at a mean of 15 mm (SD, 4.5 mm) distal to the tip of the fibula in patients with flat feet, at a mean of 20 mm (SD, 4.8 mm) in normal feet, and at a mean of 22 mm (SD, 5.4 mm) in cavus feet. The difference in the DFC within the 3 different foot type groups was significant (P < .05).

Conclusions: The DOPP was shown to be highly reliable in measuring the DFC (intraclass coefficient, 0.99). A numeric distance scale for use in all different foot morphologies could not be constructed. There is a direct relation between portal location and foot morphology (P < .05): in flat feet the portal location is significantly more proximal (15 mm) to the tip of the fibula when compared with cavus feet (22 mm).

Clinical Relevance: These results may help with portal placement in endoscopic calcaneoplasty for all different foot morphologies.