What is the step-by-step procedure for calcaneum pin insertion in an adult patient with a calcaneal fracture?

Calcaneum Pin Insertion: Step-by-Step Procedure

The posteromedial approach at three-quarters the distance from the medial malleolus tip to the heel, with transverse pin insertion, is the safest and most reproducible technique for calcaneal pin placement. 1

Indications and Pre-Procedure Planning

• Calcaneal pin insertion is indicated for skeletal traction in calcaneal fractures, particularly displaced intra-articular fractures requiring reduction, or for external fixation constructs. 2, 3
• Obtain CT imaging without IV contrast to fully characterize the fracture pattern before pin placement, as radiographs have only 87% sensitivity for calcaneal fractures. 2, 4
• Assess soft tissue status for skin compromise, abrasions, or compartment syndrome before proceeding. 3

Anatomic Landmarks and Safe Zone Identification

Identify three palpable landmarks on the medial ankle:

• Point A: Posteroinferior aspect of the medial calcaneus (posterior superior portion of calcaneal tuberosity) 5, 6
• Point B: Inferior tip of the medial malleolus 5, 1
• Point C: Navicular tuberosity 5, 6

The optimal entry point is located at 75% of the distance from Point B (medial malleolus) to Point A (posterior calcaneus), measuring from the malleolus posteriorly. 5, 1 This posteromedial site is safer and easier to determine than anteromedial approaches. 1

Critical Structures at Risk

• The medial calcaneal nerve (MCN) is the structure at greatest risk, most commonly presenting as two independent branches—one arising before tibial nerve bifurcation and another from the medial plantar nerve. 5
• The posterior branches of the lateral plantar nerve, medial plantar nerve, and posterior tibial artery are also vulnerable. 6
• Placing the pin too far posteriorly risks avulsion fracture of the calcaneus. 5
• Even within the defined safe zone, complete avoidance of the MCN may not be possible, potentially resulting in sensory loss to the sole of the foot. 5

Step-by-Step Insertion Technique

Step 1: Patient Positioning

• Position the patient supine with the affected leg externally rotated to expose the medial heel. 1
• Ensure adequate lighting and sterile field preparation. 1

Step 2: Landmark Identification and Marking

• Palpate and mark Point B (inferior tip of medial malleolus) and Point A (posterior superior calcaneal tuberosity). 1, 6
• Measure the distance between these points and mark the entry site at 75% of this distance from Point B toward Point A. 5, 1

Step 3: Skin Preparation and Anesthesia

• Prepare the skin with antiseptic solution over a wide area. 1
• Infiltrate local anesthetic at the planned entry site if the patient is awake. 1

Step 4: Blunt Dissection

• Make a small stab incision at the marked entry point. 6
• Use careful blunt dissection with a hemostat to spread tissues down to bone, protecting neurovascular structures. 6
• Consider using a cannula to protect soft tissues during pin passage. 6

Step 5: Pin Insertion

• Insert a Steinmann pin transversely (perpendicular to the long axis of the leg) through the prepared entry site. 1
• Direct the pin laterally across the calcaneus, maintaining a horizontal trajectory. 1
• Avoid angling the pin inferiorly or superiorly, as this increases risk of neurovascular injury or subtalar joint violation. 1

Step 6: Confirmation of Position

• Confirm pin placement with fluoroscopy in both lateral and axial views to ensure:
  • The pin traverses the calcaneus centrally without subtalar joint penetration 1
  • Adequate bone purchase on both medial and lateral cortices 1
  • No violation of the calcaneocuboid joint anteriorly 7

Step 7: Pin Fixation

• Secure the pin with appropriate traction apparatus or external fixation clamps. 1
• Apply sterile dressings at pin entry and exit sites. 1

Critical Pitfalls to Avoid

• Never place the pin anterior to the halfway point between Points A and B, as this dramatically increases neurovascular injury risk. 6
• Avoid excessive posterior placement beyond 75-80% of the A-B distance, which risks avulsion fracture. 5
• Do not angle the pin inferolaterally unless using the anteromedial sustentaculum tali approach (25-30 degrees), which is less safe and harder to reproduce. 1
• The medial calcaneal nerve and posterior branch of the lateral plantar nerve remain at significant risk even within the safe zone—warn patients of potential sensory loss to the heel. 6

Post-Procedure Management

• Maintain non-weight-bearing status until radiographic evidence of healing, typically 8-12 weeks for fractures. 4
• Monitor pin sites daily for signs of infection. 3
• Initiate physical therapy for range of motion restoration once appropriate. 4, 3