Evidence-Based Rehabilitation Protocol: High Ankle (Syndesmotic) Sprain

Disclaimer: This protocol is intended for professional reference by physical therapists, athletic trainers, and medical providers. It does not replace direct medical advice. Progression through phases should be based on functional criteria and tissue healing status, not solely on timeframes. High ankle sprains generally require a significantly longer recovery period than lateral ankle sprains.

1. Clinical Overview and Pathophysiology

A high ankle sprain refers to an injury of the distal tibiofibular syndesmosis. Unlike the more common lateral ankle sprain (involving the ATFL/CFL), a syndesmotic injury involves the complex ligamentous structures that maintain the stability of the ankle mortise—specifically the relationship between the distal tibia and fibula. This stability is crucial for weight-bearing, as the talus acts as a wedge that pushes the tibia and fibula apart during dorsiflexion.

Pertinent Anatomy: The stability of the syndesmosis depends on four primary structures:

• Anterior Inferior Tibiofibular Ligament (AITFL): The most commonly injured structure in high ankle sprains.
• Posterior Inferior Tibiofibular Ligament (PITFL): Stronger than the AITFL; often remains intact unless there is a fracture (such as a posterior malleolar fracture).
• Interosseous Membrane (IOM): Connects the shafts of the tibia and fibula. Extensive tears here indicate severe instability.
• Transverse Tibiofibular Ligament: Provides additional posterior stability.

Mechanism of Injury (MOI): The classic mechanism is forceful external rotation of the foot while the ankle is dorsiflexed and the foot is planted. This forces the talus to rotate laterally within the mortise, separating the tibia and fibula. This injury is common in contact sports (e.g., a pile-up in football) or skiing.

Pathophysiological Considerations for Rehab: Because the ankle mortise widens during dorsiflexion, loading the ankle in dorsiflexion places tensile stress on the healing syndesmotic ligaments. Therefore, unlike lateral sprains where early motion is encouraged, high ankle sprains often require a period of immobilization and restricted dorsiflexion to allow the ligaments to tighten and heal properly. Failure to protect the mortise can lead to chronic instability, heterotopic ossification, and early onset osteoarthritis.

2. Phase I: Protection and Acute Management (Weeks 0–3)

Goal: Protect the healing syndesmosis, manage edema, and maintain proximal strength without stressing the distal tibiofibular joint. Conservative management typically requires non-weight bearing (NWB) or partial weight-bearing (PWB) in a CAM boot depending on the grade of injury.

Precautions: Avoid external rotation of the foot and end-range dorsiflexion.

Interventions and Exercises:

• Immobilization: Use of a tall CAM walking boot. Crutches are utilized until the patient can walk with a pain-free gait.
• Edema Control: RICE (Rest, Ice, Compression, Elevation) and retrograde massage to limit joint effusion.
• Proximal Strengthening (Open Chain):
  • Straight Leg Raises (4-way: flexion, abduction, adduction, extension) to maintain hip strength.
  • Seated knee extension.
  • Hamstring curls (prone or seated).
• Core Musculature: Dead bugs and plank variations (knees only, protecting the ankle).
• Intrinsic Foot Strength: Toe curls (towel scrunches) and marble pickups to maintain arch integrity without ankle joint motion.
• Cardiovascular Maintenance: Stationary bike (low resistance) usually permitted only if the boot is worn or if pain-free, though upper-body ergometer is preferred initially.

3. Phase II: Progressive Loading and Stabilization (Weeks 3–6)

Entry Criteria: Minimal pain/tenderness over the AITFL, significant reduction in edema, and ability to bear weight without pain in the boot.

Goal: Normalize gait mechanics, restore full range of motion (ROM) conservatively, and initiate closed kinetic chain strengthening. Note: Dorsiflexion is reintroduced slowly.

Interventions and Exercises:

• Gait Training: Weaning from the boot into a rigid ankle brace. Progression from PWB to Full Weight Bearing (FWB). Emphasis on proper heel-strike to toe-off mechanics without compensatory external rotation.
• Range of Motion:
  • Gastrocnemius/Soleus stretching (towel stretch) – cautious progression.
  • Ankle alphabet (AROM).
  • Joint mobilizations: Grade I-II talocrural mobilizations if stiffness is present (avoid separating tib-fib).
• Strengthening (Isometric to Isotonic):
  • Isometric inversion and eversion against resistance.
  • Resisted plantarflexion (Theraband).
  • Double Leg Calf Raises: Performed on flat ground.
  • Leg Press: Low weight, ensuring feet are neutral (not externally rotated).
• Proprioception and Balance:
  • Single leg balance on stable surface (eyes open → eyes closed).
  • Tandem stance balance.

4. Phase III: Functional Strengthening and Return to Sport (Weeks 6–10+)

Entry Criteria: Full pain-free ROM (including dorsiflexion), symmetric calf strength, normal gait without bracing, and ability to perform a single-leg balance for 30 seconds without deviation.

Goal: Maximize power, neuromuscular control, and specific sport adaptations. The focus shifts to dynamic stability during high-velocity movements.

Interventions and Exercises:

• Advanced Strengthening:
  • Single Leg Calf Raises: Progressing to performing off a step for increased eccentric load.
  • Squats and Lunges: Monitor for tibial internal rotation control (preventing dynamic valgus).
  • Romanian Deadlifts (Single Leg): To integrate posterior chain control with ankle stability.
• Dynamic Neuromuscular Control:
  • BOSU ball squats and balance drills.
  • Star Excursion Balance Test (SEBT) training.
• Plyometrics (Progressive):
  • Double leg hops (linear).
  • Single leg hops (linear).
  • Lateral bounding (skater jumps) – introduced late, as this stresses the syndesmosis.
  • Box jumps (emphasis on soft landing mechanics).
• Agility: Ladder drills, figure-8 running, and cutting maneuvers. Cutting should begin at 50% speed and progress to 100%.

5. Return to Play (RTP) Criteria

Returning to sport with a syndesmotic sprain prematurely carries a high risk of re-injury and chronic instability. The patient must clear all clinical and functional testing metrics before full clearance.

Clinical Criteria:

• Pain: Absence of pain with palpation of the AITFL and along the interosseous membrane.
• ROM: Full, symmetrical active and passive range of motion, specifically dorsiflexion (measured via Knee-to-Wall test).
• Strength: Isokinetic or handheld dynamometry showing >90% strength symmetry of plantarflexion, dorsiflexion, inversion, and eversion compared to the contralateral limb.

Functional Performance Testing:

The patient must complete the following with >90% Limb Symmetry Index (LSI):

• Single Leg Hop for Distance.
• Triple Hop for Distance.
• Crossover Hop for Distance.
• Vertical Jump.

Sport-Specific Validation:

The athlete must complete a full practice session involving contact (if applicable) and sport-specific cutting/pivoting without pain, swelling, or apprehension. Taping or semi-rigid bracing is often recommended for the first season following a high ankle sprain to limit end-range external rotation and dorsiflexion.