Summary

The Cuboid is the keystone of the Lateral Column of the foot. Fractures are rare in isolation and are usually the result of a "Nutcracker" mechanism—forced abduction of the forefoot which crushes the cuboid between the calcaneus and the 4th/5th metatarsals. The critical goal of management is maintaining Lateral Column Length. If the cuboid remains crushed (shortened), the foot collapses into a severe abduction deformity (Flatfoot) with secondary arthritis of the midfoot. Operative fixation (ORIF or Ex-Fix) is required for displaced fractures to restore articular congruity and length. [1,2,3]

Key Facts

• The Nutcracker: Imagine a nutcracker closing. The Calcaneus is one arm, the Metatarsals are the other. The Cuboid is the nut in the middle that gets crushed during forced abduction/eversion.
• The Peroneal Groove: The undersurface of the cuboid has a deep groove for the Peroneus Longus tendon. Fractures here can entrap or irritate the tendon.
• Associated Injuries: Cuboid fractures rarely travel alone. Look for:
  • Lisfranc injuries.
  • Navicular fractures (Medial column distraction).
  • Calcaneal Anterior Process fractures.

Clinical Pearls

"The Painful Snap": Patients often describe a snap on the outside of the foot after stumbling into a massive hole or falling from a height.

"Check the Length": Compare the X-ray to the other foot. Is the 4th/5th ray shorter? If yes, the lateral column has collapsed.

"Hidden in Plain Sight": On AP X-ray, the cuboid is often obscured. The Oblique View (Medial Oblique) is the money shot for seeing the Calcaneocuboid joint.

                 CUBOID FRACTURE
                        ↓
             IS IT SHORT OR DISPLACED?
            ┌────────────┴─────────────┐
           NO                         YES
      (<2mm Step)              (Short / >2mm Step)
      (Length OK)                      ↓
           ↓                  SURGICAL RECON
      CONSERVATIVE           ┌─────────┴─────────┐
     (Cast NWB 6w)         PLATE               EX-FIX
                         (Primary)           (Distraction)
                             ↓                   ↓
                         BONE GRAFT?        (If severe skin
                                              issues)

Indications

• Non-displaced fractures.
• Avulsion fractures (common).
• Preserved lateral column length (No shortening).

Protocol

• Cast: Short leg cast, Non-Weight Bearing (NWB) for 6-8 weeks.
• Warning: Do not allow early weight bearing, as the cuboid can collapse late (like the navicular).
• X-Rays: Weekly for first 3 weeks to ensure no displacement.

Indications

• Loss of Length: Any shortening of the lateral column.
• Articular Step-off: >2mm at Calcaneocuboid or Tarsometatarsal joints.
• Comminution: "Exploded" cuboid.

Technique: ORIF

• Approach: Direct lateral incision. Watch out for Sural Nerve (dorsal) and Peroneal Tendons (plantar).
• Reduction:
  • Use a Mini-Distractor or Lamina Spreader between Calcaneus and Mets to regain length.
  • "Jack" the articular surface back up.
• Fixation:
  • Bridge Plate: Spans from Calcaneus to 4th/5th Metatarsal (bypasses the cuboid initially to hold length).
  • Locking Plate: Lateral plate on the cuboid itself (if fragments large enough).
• Bone Graft: Often needed to fill the void left after elevating the crush.

Technique: External Fixation

• Used if soft tissues are compromised (severe swelling/blisters).
• Pins in Calcaneus and 4th/5th Mets. Distract to restore length.

Bridge Plating

• Weber et al: Showed that for comminuted fractures, bridge plating (spanning the joint) provides better maintenance of length than trying to put tiny screws into cuboid dust. The plate is removed at 4-6 months.

Importance of Length

• Biomechanical studies confirm that lateral column shortening of even 3-4mm significantly alters the loading of the medial column, leading to flatfoot deformity.

The Injury

You have crushed the "outer block" of your foot's arch. It's like a nutcracker crushed it.

The Risk

If this bone heals "short" (squashed), your foot will drift outwards and become flat. This will cause pain in your arch forever.

The Fix

We need to stretch the foot back out to its proper length. We will use a metal plate to bridge the gap and hold it out to length while the crushed bone heals inside. We might need to take some bone graft (from your heel) to fill the gaps.

Q1: What is a "Nutcracker Fracture"? A: A compression fracture of the cuboid caused by forced forefoot abduction. The cuboid is crushed between the calcaneus and the 4th/5th metatarsal bases.

Q2: Which tendon runs in the groove of the cuboid? A: Peroneus Longus. It runs from lateral to medial across the sole to insert on the 1st Metatarsal/Medial Cuneiform (plantarflexing the 1st ray).

Q3: Why is lateral column length important? A: The lateral column acts as a rigid lever arm. Shortening leads to forefoot abduction (Pes Planus Valgus) and uncouples the medial column, causing arch collapse.

Q4: What is the primary surgical strategy for severe comminution? A: Dorsolateral Bridge Plating. Spanning from the Calcaneus to the 4th/5th Metatarsals to maintain length and alignment, allowing the comminuted cuboid to heal without compressive load.

(End of Topic)