Physical Therapy Rehabilitation Protocol: Achilles Tendon Rupture

Disclaimer: This protocol is intended as a professional evidence-based guideline for licensed physical therapists. It is based on current best practices for accelerated functional rehabilitation. However, all rehabilitation must be individualized based on the patient's surgical status (operative vs. non-operative), tissue quality, and the specific limitations prescribed by the referring orthopedic surgeon.

1. Clinical Overview and Pathophysiology

The Achilles tendon is the strongest and thickest tendon in the human body, formed by the conjoined tendons of the gastrocnemius and soleus muscles, inserting onto the calcaneus. Despite its strength, it is frequently ruptured, particularly in the "weekend warrior" demographic (males aged 30–50). Ruptures typically occur during high-velocity eccentric loading, such as pushing off for a sprint or jumping, where the demand on the musculotendinous unit exceeds its tensile strength.

Pathophysiology: Most ruptures occur in the "watershed zone" (approximately 2–6 cm proximal to the calcaneal insertion). This area has relatively poor vascular supply compared to the rest of the tendon, predisposing it to degenerative changes (tendinosis) prior to rupture. Histological examination of ruptured tendons often reveals chaotic collagen arrangement, neovascularization, and mucoid degeneration, suggesting that the rupture is frequently the acute manifestation of a chronic underlying pathology.

Current evidence supports "early functional mobilization" over traditional immobilization (casting). Functional rehabilitation promotes organized collagen remodeling, reduces muscle atrophy, and prevents adhesion formation without significantly increasing the re-rupture rate compared to rigid immobilization.

Phase I: Protection and Acute Management (Weeks 0–6)

Goal: Protect the healing tendon, manage edema, minimize muscle atrophy of the proximal chain, and gradually introduce weight-bearing (WB) based on surgical guidelines.

Precautions: Avoid passive dorsiflexion (DF) stretching. No active plantarflexion (PF) against resistance. Protect the repair site at all times.

Rehabilitation Timeline

• Weeks 0–2: Non-weight bearing (NWB) with crutches. The foot is immobilized in a splint or boot in 20–30 degrees of plantarflexion (equinus position) to approximate tendon ends.
• Weeks 2–4: Progression to weight-bearing as tolerated (WBAT) in a controlled ankle motion (CAM) boot with heel wedges.
• Weeks 4–6: Gradual removal of heel wedges to bring the ankle to neutral position within the boot.

Specific Therapeutic Exercises

• Proximal Conditioning: Side-lying hip abduction (clamshells), straight leg raises (flexion, abduction, extension), and seated quadriceps activation.
• Intrinsic Foot Activation: Toe curls (towel scrunches) to maintain intrinsic foot strength and minimize distal edema.
• Core Stabilization: Dead bug progression and plank modifications (knees only) to maintain trunk stability while NWB.
• Cardiovascular: Upper body ergometer (arm bike).

Phase II: Functional Loading and Strengthening (Weeks 6–12)

Goal: Restore full range of motion (ROM), normalize gait mechanics out of the boot, increase tensile load capacity of the tendon, and improve proprioception.

Criteria for Entry: Full weight-bearing in boot without pain, healed incision site, and clearance from surgeon to wean from boot.

Rehabilitation Timeline

• Weaning Process: Transition from boot to shoe with a heel lift (if necessary). Use a "boot-to-shoe" progression over 10–14 days.
• Gait Training: Focus on restoring the stance phase and preventing hip hiking or circumduction.
• ROM: Gentle stretching to neutral dorsiflexion. Avoid aggressive stretching past neutral until Week 10–12.

Specific Therapeutic Exercises

• Isometrics: Sub-maximal isometric plantarflexion at neutral (seated, pressing against wall or therapist hand).
• Concentric Strengthening:
  • Seated Heel Raises: Targets the soleus. Perform with knees bent to 90 degrees. Add weight plates on knees as tolerated.
  • Standing Bilateral Heel Raises: Initiate on flat ground. Focus on equal weight distribution to prevent the uninjured side from compensating.
  • Resistance Band Work: Four-way ankle strengthening (inversion, eversion, plantarflexion). Continue to avoid end-range dorsiflexion stretching.
• Proprioception: Single-leg stance (eyes open to eyes closed), rocker board balance training (sagittal plane only initially).
• Cardiovascular: Stationary cycling (low resistance, heel strictly on pedal to avoid forefoot loading) and elliptical trainer.

Phase III: Return to Sport and Plyometrics (Months 3–6+)

Goal: Develop eccentric strength, power, speed, and agility. Return to pre-injury level of activity.

Precautions: Monitor for morning stiffness or localized pain greater than 3/10. Load management is critical to prevent reactive tendinopathy.

Specific Therapeutic Exercises

• Eccentric Loading (The Alfredson Protocol adaptation):
  • Eccentric Heel Drops: Raise up on two feet, lower slowly (4 seconds) on the injured single limb. Perform with both straight knee (gastroc focus) and bent knee (soleus focus).
• Advanced Strengthening: Single-leg calf raises with added weight (dumbbell/kettlebell). Leg press calf raises.
• Plyometric Progression (Criteria: Ability to perform 10 single-leg heel raises):
  • Level 1: Double leg pogo jumps in place.
  • Level 2: Box jumps (landing mechanics focus).
  • Level 3: Single-leg hopping, bounding, and lateral agility ladder drills.
• Sport-Specific Drills: Cutting, deceleration drills, and sprinting mechanics.

Return to Play (RTP) Criteria

Time alone is not a sufficient criterion for return to sport. The patient must pass functional testing to minimize re-injury risk. Generally, RTP occurs between 6 to 9 months post-injury.

• Range of Motion: Symmetrical dorsiflexion ROM (knee extended and flexed) compared to the contralateral limb.
• Strength Endurance (The Gold Standard): Single Leg Heel Rise Test.
  • Patient performs single-leg heel rises to a metronome (30 beats/min).
  • Target: Limb Symmetry Index (LSI) > 90% of the uninjured side regarding total repetition count and total work height.
• Hop Testing:
  • LSI > 90% on Single Hop for Distance, Triple Hop for Distance, and Crossover Hop.
• Psychological Readiness: No apprehension during sport-specific movements.