Summary

The Triple Arthrodesis is the ultimate salvage procedure for severe hindfoot deformity and arthritis. It involves the surgical fusion of 3 joints: the Subtalar, Talonavicular, and Calcaneocuboid. By locking these joints together, the hindfoot is converted into a stable, painless, plantigrade block. It is indicated for rigid deformities (Flatfoot Stage 4, Cavovarus/CMT) or inflammatory arthritis where single-joint fusions would fail. While effective, it comes at a cost: the loss of shock absorption leads to eventual degeneration of the Ankle and Midfoot joints. [1,2,3]

Key Facts

• The Three Joints:
  1. Subtalar (ST): Talus + Calcaneus. Primary motion: Inversion/Eversion.
  2. Talonavicular (TN): Talus + Navicular. Primary motion: Rotation (Acetabulum Pedis).
  3. Calcaneocuboid (CC): Calcaneus + Cuboid. Primary motion: Stability.
• The "Double" vs "Triple": Modern trends are checking if we really need to fuse the CC joint. A "Double Arthrodesis" (TN + ST) spares the lateral column, potentially reducing non-union rates while achieving similar correction.
• The Sequelae: After a Triple, the ankle takes 100% of the rotational stress. Ankle arthritis typically develops 10-20 years post-op.

Clinical Pearls

"Position is Everything": A fused foot cannot compensate. If fused in Varus, the patient walks on the lateral border (painful). If fused in too much Valgus, they impinge laterally. 5 Degrees of Valgus is the target.

"The TN Joint is the Key": The Talonavicular joint is the "Coxa Pedis". Fusing just this one joint eliminates 90% of hindfoot motion. It is the hardest to get to heal.

"The Peg Leg Effect": If a patient already has a stiff ankle, doing a Triple produces a "pantalafusion" effect (even without fusing the ankle), making walking extremely difficult.

                 RIGID HINDFOOT DEFORMITY
                          ↓
                   ANKLE JOINT OK?
             ┌────────────┴────────────┐
            NO                        YES
            ↓                          ↓
    PANTALAR FUSION             TRIPLE ARTHRODESIS
   (Or TAR + Fusion)                   ↓
                                  MEDIAL CUT (TN)
                                       +
                                  LATERAL CUT (ST + CC)
                                       ↓
                                   FIXATION
                               (Screws / Staples)

1. Positioning

• Supine. Thigh tourniquet. Bump under ipsilateral hip.

2. Dissection

• Lateral: Incision along the dermatome of the Sural Nerve (Protect it!). Mobilize the EDB muscle belly. Expose CC and ST joints.
• Medial: Medial to Tib Ant tendon. Expose TN joint.

3. Preparation (The "Work")

• Resection: Cartilage is removed with osteotomes/curettes to expose healthy bleeding subchondral bone.
• Correction: Wedges of bone are removed to correct deformity.
  • Flatfoot: Take wedge from Medial (TN) to restore arch.
  • Cavus: Take wedge from Lateral (CC/ST) to drop the arch.

4. Fixation

• Subtalar: large (7.3mm) screw from Heel to Talus.
• Talonavicular: Two screws or a plate. (High non-union rate).
• Calcaneocuboid: Staples or Screws.

5. Closure

• Layers. Cast.

Timeline

• 0-2 Weeks: Backslab. Elevate. NWB.
• 2-6 Weeks: Cast. NWB.
• 6-12 Weeks: Walker boot. Partial Weight Bearing -> Full Weight Bearing.
• 3 Months: X-ray check. If fused -> Shoe.
• 6 Months: Full recovery.

Triple vs Double?

• Phisitkul et al: Suggest that sparing the Calcaneocuboid joint (Double Arthrodesis) preserves lateral column length and reduces non-union rates without compromising deformity correction in Planovalgus feet.

Long Term Outcome

• Saltzman et al: 25 and 44 year follow-ups show that while 95% of patients remain satisfied with the pain relief, nearly 100% have radiographic arthritis of the ankle.

The Surgery

We are going to permanently lock the back half of your foot. We will clean out the 3 arthritic joints and screw them together so they grow into one solid block of bone.

The Trade-off

You will lose your ability to wiggle your foot side-to-side (accommodate to uneven ground). But your up-and-down ankle motion will stay. Most importantly, the deformity will be straight, and the pain will be gone.

The Future

Because the foot is stiff, your ankle has to work harder. In 15-20 years, your ankle might wear out. But for now, this is the only way to fix the deformity.

Q1: What are the three joints of a Triple Arthrodesis? A:

1. Subtalar (Talocalcaneal).
2. Talonavicular.
3. Calcaneocuboid.

Q2: Which joint is the "Acetabulum Pedis" and why? A: Talonavicular Joint. The spherical head of the talus fits into the socket of the navicular (and spring ligament). It is the key to hindfoot motion. Fusing it eliminates >90% of complex hindfoot movement.

Q3: Why is 5 degrees of Valgus the target position? A: Slight Valgus is stable during the stance phase of gait. Varus positions the foot on the lateral border, causing instability and pain under the 5th metatarsal (Lateral Column Overload).

Q4: What is a "Lambrinudi Arthrodesis"? A: A specific type of Triple Arthrodesis used for Drop Foot (Polio/Nerve injury). A wedge is removed from the talus to fuse the foot in slight plantarflexion, preventing the foot from dropping during swing phase.

(End of Topic)