What are the primary anatomical landmarks to consider when applying calcaneum traction?

Calcaneum Traction Landmarks

When applying calcaneal traction, the primary anatomical landmarks are the posteroinferior medial calcaneus (Point A), the inferior medial malleolus (Point B), and the navicular tuberosity (Point C), with the safest pin placement being posterior to the halfway point between Points A and B medially, and posterior to the one-third mark between Points A and C. 1

Critical Anatomical Landmarks for Pin Placement

Medial Approach Safe Zones

• Point A (Posteroinferior Medial Calcaneus): This serves as the primary reference point for all measurements on the medial aspect 1
• Point B (Inferior Medial Malleolus): Used to establish the superior safe zone boundary 1
• Point C (Navicular Tuberosity): Used to establish the anterior safe zone boundary 1

Specific Safe Zone Parameters

• Superior-Inferior Axis: Place pins posterior to the halfway point from Point A to Point B—the more posterior within this zone, the safer 1
• Anterior-Posterior Axis: Place pins posterior to the one-third mark from Point A to C—again, more posterior placement is safer 1

Neurovascular Structures at Risk

The medial calcaneus has a very limited safe window due to critical neurovascular structures 1:

• Medial calcaneal nerve: At significant risk at the margins of the safe zones 1
• Lateral plantar nerve and its most posterior branch: These structures are vulnerable to direct injury or abutment by pins placed outside the safe zones 1
• Medial plantar nerve: Also at risk during medial approaches 1
• Posterior tibial artery: The major vascular structure is located medially and well-insulated by soft tissues, but remains at risk during medial approaches 2

Lateral Anatomical Considerations

Palpable Bony Landmarks

• The lateral aspect has several palpable bony landmarks due to relative paucity of soft tissue 2
• Lateral calcaneal wall: Easily palpable and useful for orientation 3
• Posterior superior calcaneus: Important landmark for excluding pathology 3
• Achilles insertion: Critical landmark for superior orientation 3

Lateral Approach Risks

• Lateral approaches have been associated with skin necrosis, potentially related to arterial anatomy 2
• The lateral soft tissues are relatively thin compared to the medial side 2

Surface Anatomy of the Calcaneal Tuberosity

Tuberosity Facets

• The calcaneal tuberosity has three distinct facets: superior, middle, and inferior 4
• Two borders separate these facets, with the inferior line (corresponding to the distal circumference of Achilles tendon attachment) showing more frequent medial declination 4

Internal Architecture

• Two systems of cancellous bone condensation exist just below the surface of the calcaneal tuberosity 4
• The calcaneus is designed to sustain high tensile, bending, and compressive forces 2

Technical Recommendations for Pin Placement

Preparation and Technique

• Use careful blunt dissection before pin insertion 1
• Consider using cannulas to help avoid neurovascular injury 1
• When using a distractor for fracture reduction, varus of the calcaneus should be reduced first 5

Common Pitfall

The medial calcaneus provides only a small window for safe percutaneous pin placement 1. The most common error is placing pins too anteriorly or too superiorly, which significantly increases the risk of neurovascular injury. Always err on the side of more posterior placement within the defined safe zones 1.