Summary

The Tarsal Navicular is the Keystone of the medial longitudinal arch, responsible for structural integrity and gait mechanics. Fractures occur in two distinct populations: high-energy trauma (crush/MVA) causing comminuted body fractures, and repetitive micro-trauma in athletes causing Stress Fractures. The Navicular is notoriously unforgiving due to its centrifugal blood supply, which leaves the central third as a "Watershed Area" prone to non-union and Avascular Necrosis (AVN). Management requires aggressive reconstruction (ORIF) for trauma and strict non-weight bearing for stress fractures. [1,2,3]

Key Facts

• The "Scaphoid of the Foot": Like the scaphoid in the wrist, the navicular has a precarious blood supply and is prone to AVN.
• The Watershed Area: The central third of the bone receives blood from neither the dorsal nor plantar arteries, making it the primary site for stress fractures and non-unions.
• N-Spot Tenderness: The hallmark sign of a Navicular Stress Fracture. Point tenderness on the dorsal aspect of the navicular, between the Tibialis Anterior and EHL tendons.

Clinical Pearls

"It's not just a sprain": A midfoot sprain in a sprinter or jumper with N-Spot tenderness is a Navicular Stress Fracture until proved otherwise. X-rays are usually negative. MRI is mandatory.

"Respect the CT": X-rays wildly underestimate the comminution of traumatic fractures. A CT scan is essential for pre-operative planning of screw trajectories.

"Fix the Column": The goal of surgery is not just to fix the bone, but to restore the length of the medial column. If the navicular collapses (shortens), the foot drifts into Varus/Adductus.

                 NAVICULAR INJURY
                        ↓
            TRAUMA OR STRESS FRACTURE?
           ┌────────────┴─────────────┐
        TRAUMA                      STRESS
    (High Energy)                (Athlete)
         ↓                            ↓
    CT SCAN (Sangeorzan)         MRI CONFIRMED
    ┌────┴────┐                  ┌────┴────┐
NON-DISP    DISP             NON-DISP    DISP
   ↓          ↓                  ↓         ↓
 CAST       ORIF               CAST       ORIF
(6-8w)    (Plate/Screw)       (NWB 6w)  (Screw)

Indications

• Trauma: Non-displaced fractures (<1mm step-off). Avulsion fractures of the tuberosity.
• Stress: Non-displaced partial fractures.

Protocol

• Trauma: Short leg cast, Non-Weight Bearing (NWB) for 6-8 weeks.
• Stress: Strict NWB Cast for 6-8 weeks.
  • Walking Boots FAIL: Studies show high non-union rates with walking boots because they allow too much motion. The patient must be NWB.
• Follow-up: CT scan at 8 weeks to confirm bridging before weight bearing.

Indications

• Trauma:
  • Displacement >1mm.
  • Medial column shortening.
  • Joint subluxation (Talonavicular).
• Stress:
  • Displaced fracture.
  • Complete fracture line on CT.
  • Failed conservative management (Non-union).
  • Elite athletes (faster predictable return, but higher risk).

Technique: ORIF

• Approach: Anteromedial incision (Interval: Tibialis Anterior / Posterior Tibial Tendon).
• Reduction: Use a distractor (Lamina spreader) to regain medial column length.
• Fixation:
  • Trauma: Medial plate (buttress) + interfragmentary screws. Bridge plating for severe comminution.
  • Stress: Percutaneous 4.0mm Cannulated Screw. Perpendicular to fracture line.

Salvage: Fusion

• For Type 3 comminuted fractures that cannot be reconstructed, Primary Arthrodesis (Fusion) to the cuneiforms is preferred to salvage length.

The "Walking Boot" Trap

• Torg et al: Demonstrated that Navicular stress fractures managed with weight-bearing (boot) had a high rate of non-union/recurrence/AVN compared to strict NWB casting. Standard of Care is NWB Cast.

Screw Direction

• For stress fractures, the screw should be placed from Lateral to Medial (or vice versa depending on fracture plane) to achieve compression.

The Injury

You have broken the keystone of your foot's arch. This is a very fussy bone with a poor blood supply.

The Problem

If this bone doesn't heal perfectly, your whole arch will collapse, and you will develop severe arthritis.

The Treatment

• Stress Fracture: You must be on crutches with a cast for 6 weeks. No cheating. If you walk on it, it will not heal, and you will need surgery.
• Trauma: We need to rebuild the bone with plates and screws to hold the shape of your foot while it heals.

Return to Sport

• Slow. Expect 4-6 months minimum for sprints.

Q1: What is the "N-Spot"? A: The high point of the arch on the dorsal aspect of the navicular. Tenderness here is specific for stress pathology.

Q2: Describe the blood supply to the Navicular. A: Centrifugal. Supplied by branches of the Dorsalis Pedis (dorsal) and Medial Plantar Artery (plantar). The central third is a watershed zone.

Q3: What is the Sangeorzan Classification Type 2? A: A dorsolateral to plantar-medial fracture line. The major medially displaced fragment contains the tuberosity and pulls the forefoot into adduction.

Q4: Can you treat a Navicular Stress Fracture in a moon boot? A: No. Or strictly speaking, you shouldn't. Evidence suggests weight bearing in a boot leads to unacceptably high non-union rates. Strict NWB casting is the gold standard.

(End of Topic)