A new point for calcaneal pin insertion: A radiographic study measuring bone density on computed tomography

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Radiology

Background:

• External fixator schanz pins are commonly placed in the calcaneal mid-portion.
• This region exhibits lower bone density, increasing the risk of pin loosening.
• An alternative posterior calcaneal site is proposed for enhanced stability and safety.

Purpose of the Study:

• To evaluate bone density differences between the traditional calcaneal pin insertion site and a proposed posterior calcaneal site.
• To compare the safety and rigidity of pin placement in these two locations.
• To inform optimal surgical techniques for calcaneal fracture fixation.

Main Methods:

• Retrospective analysis of 46 ankle computed tomography (CT) scans.
• Measurement of Hounsfield Units (HU) to assess bone density at traditional and posterior calcaneal points.
• Statistical analysis using Shapiro-Wilk and Wilcoxon Signed Ranks tests.

Main Results:

• The posterior calcaneal point showed significantly higher bone density (335 HU) compared to the traditional point (202 HU) (p < 0.001).
• Excellent inter-rater reliability was achieved for bone density measurements (ICC > 0.87).
• The posterior site offers greater distance from critical neurovascular structures.

Conclusions:

• The posterior fifth of the calcaneus provides a denser and potentially more stable bone site for external fixator pin insertion.
• This anatomical location offers improved safety by increasing the distance to neurovascular structures.
• Higher bone density correlates with improved screw pull-out strength, suggesting better fixation.