Summary

Subtalar Arthritis is the degeneration of the talocalcaneal joint, predominantly affecting the Posterior Facet. Like the ankle, it is overwhelmingly Post-Traumatic in origin, most commonly following a Calcaneal Fracture (intra-articular) or Talus Fracture. Patients present with a distinct inability to walk on uneven ground ("cobblestones"), as the subtalar joint's primary function is accommodating terrain (inversion/eversion). Management is initially conservative (bracing) but often progresses to Subtalar Fusion (Arthrodesis), which is one of the most successful operations in foot and ankle surgery with >90% satisfaction rates. [1,2,3]

Key Facts

• The Accommodator: The subtalar joint converts the rotation of the leg into inversion/eversion of the foot, allowing us to walk on non-flat surfaces. Loss of this joint (arthritis or fusion) means the patient struggles on hills or rocky ground.
• The "Widened Heel": After Calcaneal fractures, the heel often heals "short and wide" (Blowout), causing lateral impingement against the fibula.
• The Coalition Factor: In patients with no history of trauma, suspect a Tarsal Coalition (Middle facet) that has altered mechanics for decades.

Clinical Pearls

"The Cobblestone Sign": Ask the patient: "Can you walk on a beach or a gravel driveway?" If they say "No, it hurts deeply," it is Subtalar Arthritis. Ankle arthritis patients struggle more with hills (dorsiflexion).

"Where is the pain?": Subtalar pain is felt in the Sinus Tarsi (lateral) or deep in the heel. It is NOT usually felt anteriorly (Ankle).

"The Diagnostic Block": Because Ankle and Subtalar pain overlap (and 20% exist together), injecting the Subtalar joint with local anesthetic is mandatory before surgery to confirm the pain source.

                 SUBTALAR PAIN
                       ↓
             X-RAY: JOINT NARROWING
                       ↓
                DIAGNOSTIC BLOCK
               (To confirm source)
              ┌───────┴───────┐
          RELIEF           NO RELIEF
             ↓             (Look at Ankle/Tendons)
        TRUE ST OA
             ↓
        CONSERVATIVE
      (Brace, Virgin, Steroid)
             ↓
          FAILED?
             ↓
          SURGERY
      (Subtalar Fusion)

Indications

• Mild symptoms.
• Preserved motion.
• Contraindications to surgery.

Protocol

• Bracing:
  • ASO / Lace-up: Mild support.
  • UBC / Gauntlet: Rigid leather brace to lock inversion/eversion.
• Footwear: High-top hiking boots.
• Injections:
  • Corticosteroid: Into the Sinus Tarsi. Effective.

Subtalar Arthrodesis (Fusion)

The Gold Standard.

1. In Situ Fusion

• Indication: Arthritis with minimal deformity.
• Technique:
  • Incision over Sinus Tarsi (Ollier's approach).
  • Debride cartilage from posterior facet.
  • Fixation: 1 or 2 large cannulated screws (6.5/7.3mm) from Heel to Talus.
• Outcome: Excellent pain relief.

2. Distraction Bone Block Fusion

• Indication: Arthritis + Loss of Height (Collapsed Calcaneus).
• Rationale: The collapsed calcaneus causes anterior ankle impingement (Talar declination decreases). We need to jack the talus back up.
• Technique:
  • Large structural bone graft (Iliac Crest) inserted into the posterior facet.
  • Restores height and alignment.

3. Arthroscopic Fusion

• Indication: Mild deformity.
• Benefit: Less wound complications (sural nerve), faster healing.

The Position Matters

• Mann et al: Demonstrated that fusing the subtalar joint in Valgus (5 deg) unlocks the transverse tarsal joint (Chopart) allowing some forefoot flexibility. Fusing in Varus locks the entire foot rigid.

Success Rate

• Eastham et al: Reported 90% fusion rate and reliable pain relief for post-traumatic cases.

The Condition

The "steering joint" under your ankle bone (which lets your foot rock side-to-side) is worn out. This is usually from that heel fracture you had years ago.

The Problem

Because it's rough and stiff, walking on anything but a flat floor hurts deeply in the heel.

The Surgery

We will fuse (glue) the two bones together.

• Will I walk normally? On flat ground, yes. You won't notice much difference because it's already stiff.
• Will I run? Jogging is possible.
• Can I walk on the beach? It will be harder, as your foot won't til to match the sand.

Q1: What is the optimal position for Subtalar Fusion? A: 5 degrees of Valgus. This unlocks the transverse tarsal joint (Chopart), preserving some midfoot motion. Varus fusion locks the midfoot and causes lateral column overload.

Q2: Describe the "Distraction Bone Block" fusion. A: Used for malunited calcaneal fractures with loss of height. A tricortical iliac crest graft is inserted into the posterior facet to restore calcaneal height/talar inclination and relieve anterior ankle impingement.

Q3: Which view is best for assessing the Subtalar Joint? A: Broiden View: Internal rotation oblique views at variable angles (10, 20, 30, 40 degrees) to scan the posterior facet. Or CT.

Q4: Where do you place the screw for fusion? A: Typically from the posterior-inferior heel (calcaneus), directed antero-medially into the neck/body of the Talus.

(End of Topic)