Summary

Chronic Ankle Instability (CAI) is the persistence of symptoms (giving way, pain, swelling) >6 months after an initial ankle sprain. It affects 20-30% of sprain patients. CAI is divided into two distinct entities: Mechanical Instability (the ligaments are physically loose) and Functional Instability (the ligaments are tight, but neuromuscular control is poor). Differentiating these is critical, as functional instability is treated with proprioceptive rehab, while mechanical instability often requires surgical reconstruction (Modified Brostrom-Gould). [1,2,3]

Key Facts

• The Vicious Cycle: A sprain damages mechanoreceptors in the ligaments. This causes a delay in peroneal muscle reaction time. The next time the ankle rolls, the muscles fire too late to catch it, causing another sprain and further damage.
• The Brostrom-Gould: The Gold Standard anatomic repair. It tightens the native ATFL and CFL and reinforces them with the Extensor Retinaculum (Gould modification). It has a 90% success rate in appropriate candidates.
• The Fatal Flaw: Performing a Brostrom on a patient with a Varus Heel is destined to fail. The varus alignment puts constant tension on the repair, stretching it out. A Calcaneal Osteotomy is required.

Clinical Pearls

"Does it actually roll over?": Many patients say "my ankle is weak." Ask if it actually gives way and they fall. True mechanical instability involves actual rollover events. Pain alone is not instability.

"Beighton Score": Always check for generalized hypermobility (thumb to forearm, pinky extension, elbow/knee hyperextension). Hypermobile patients have "stretchy" collagen. A standard Brostrom may stretch out again; they often need augmentation (InternalBrace) or tendon transfer.

"The Proprioception Test": Ask the patient to stand on the bad leg with eyes closed. If they wobble significantly more than the good side, they have Functional Instability.

                 "WEAK ANKLE"
                      ↓
           MECHANICAL OR FUNCTIONAL?
          ┌───────────┴───────────┐
      FUNCTIONAL              MECHANICAL
    (Stable exam)           (Loose exam)
          ↓                       ↓
    PHYSIOTHERAPY           PHYSIOTHERAPY
   (Proprioception)        (3-6 Months)
          ↓                       ↓
       RESOLVED?               FAILED?
                                  ↓
                               SURGERY
                        (Brostrom +/- Osteotomy)

The "Nieves" Program

• Proprioception: Wobble board, Bosu ball.
• Peroneal Strengthening: Theraband eversion.
• Bracing: ASO brace for high-risk activities (Soccer/Basketball).
• Success: 50% of Mechanical Instability patients can avoid surgery with rigorous rehab.

1. Modified Brostrom-Gould Repair

• The Standard. Anatomical shortening of the native ligaments.
• Technique:
  • Incision over ATFL.
  • Capsule/ATFL cut and imbricated (pants-over-vest).
  • Extensor Retinaculum pulled up and sutured over the top (Gould).
• Augmentation (InternalBrace):
  • Modern trend. Use of a SwiveLock anchor and fiber-tape to act as a "seatbelt" protecting the repair while it heals. Allows earlier weight bearing.

2. Anatomical Reconstruction (Tendon Graft)

• Indication: Revision cases, poor tissue quality, hypermobility, weight >100kg.
• Technique: Use Hamstring autograft or Allograft to recreate ATFL/CFL tunnels.

3. Calcaneal Osteotomy (Dwyer/Lateralizing)

• Indication: Varus Heel.
• Rationale: Shifts the heel laterally to change the ground reaction force, taking tension off the lateral ligaments. Mandatory if Varus exists.

InternalBrace Augmentation

• Coetzee et al: Showed that augmenting the Brostrom with a suture-tape construct allows for accelerated rehabilitation (immediate weight bearing in boot) with no increase in complications. It is becoming the standard of care for athletes.

Brostrom vs Evans/Chrisman-Snook

• Hennrikus et al: Brostrom (Anatomic) has superior functional outcomes compared to the old non-anatomic tendon transfers (Evans/Chrisman-Snook), which sacrificed the Peroneus Brevis and caused stiffness.

The Condition

Your ligaments are stretched out like an old elastic band. They aren't snapping back to hold the ankle tight.

The Surgery (Brostrom)

We verify the loose ligaments, cut them, overlapping the ends (like double-breasting a suit), and stitch them tight. We then pull a nearby layer (retinaculum) over the top for extra strength.

The Rehab

You will be in a boot for 2-4 weeks. Then physio. No sport for 3-4 months.

Q1: What is the Gould Modification? A: The advancement of the Inferior Extensor Retinaculum over the repaired ATFL/CFL. It reinforces the repair, limits inversion, and assists in proprioception.

Q2: What is a contraindication to a Brostrom procedure? A:

• Generalized Hypermobility (Relative - needs augmentation).
• Fixed Varus Deformity (Needs osteotomy).
• Obesity (High failure rate).
• Failed prior Brostrom (Needs graft reconstruction).

Q3: Describe the Anterior Drawer test for the ankle. A: The ankle acts as a constrained pivot. With the foot in 10-20 degrees of plantarflexion (isolating ATFL), the tibia is stabilized and the heel is pulled anteriorly. >5mm translation or a "soft endpoint" compared to the contralateral side indicates laxity.

Q4: Why are non-anatomic repairs (Chrisman-Snook) largely abandoned? A: They sacrificed the Peroneus Brevis tendon (dynamic stabilizer), caused excessive stiffness (restricting normal subtalar motion), and had higher rates of osteoarthritis long-term.

(End of Topic)