Foot & Ankle: Achilles Tendon Rupture

Achilles tendon rupture is increasing in incidence, particularly in the "weekend warrior" population. The management of this injury has undergone a paradigm shift in the last decade. The debate between operative and non-operative management continues to evolve, but the focus has shifted from "repair vs. cast" to "how we rehabilitate." This comprehensive guide covers the epidemiology, anatomy, decision-making, and rehabilitation protocols essential for the Fellowship exam.

Visual Element: A high-quality anatomical illustration of the posterior leg showing the gastrocnemius-soleus complex, the 90-degree rotation of the fibers, and the watershed area of blood supply where ruptures most commonly occur.

Epidemiology

Demographics

• Peak age: 30-50 years (The "Weekend Warrior").
• Male:Female: 6:1.
• Incidence: 18-37 per 100,000 per year.
• Side: Left side is more common (often the non-dominant push-off leg in right-handed sports).

Risk Factors

Understanding risk factors is crucial for history-taking and counseling.

Anatomy Essentials

Tendon Structure

• Origin: Gastrocnemius (medial and lateral heads) and Soleus.
• Insertion: Calcaneal tuberosity (middle third).
• Length: Approximately 15cm (the longest and strongest tendon in the body).
• Rotation: The fibers spiral 90° laterally as they descend. This rotation allows for elastic energy storage but may create stress risers.

Blood Supply (The Critical Zone)

The tendon receives blood from the musculotendinous junction (proximal) and the bone-tendon interface (distal).

• Watershed Area: A zone of relative hypovascularity exists 2-6 cm proximal to the insertion.
• Significance: This is the most common site of rupture and has the poorest potential for healing.

Clinical Presentation

History

The history is often classic and diagnostic.

• Mechanism: Sudden forced dorsiflexion or push-off (acceleration).
• Sensation: "It felt like someone kicked me in the back of the leg."
• Audible: Often a loud "pop" or "snap."
• Function: Immediate inability to walk normally, though some patients can limp using accessory plantar flexors (FHL, FDL, Peroneals).

Examination

Do not rely on "unable to plantarflex." Patients can often plantarflex using accessory muscles.

Other Key Signs:

• Matles Test: Prone, knees flexed 90°. The ruptured foot falls into neutral/dorsiflexion (loss of resting tension). The normal foot remains in slight plantarflexion.
• Palpable Gap: Feel along the tendon. A "hatchet strike" defect is often palpable early before swelling fills the void.
• O'Brien Needle Test: Insert a needle into the proximal tendon. Move the foot. If the needle doesn't move, the connection is severed. (Rarely done in practice due to infection risk/pain).

Imaging

Ultrasound

The primary modality in most centers.

• Pros: Dynamic (can assess gap closure in plantarflexion), cheap, no radiation.
• Key Finding: Discontinuity of fibers, hematoma.
• Decision Making: The Apposition Gap. If the tendon ends approximate (gap < 5mm) in 20° plantarflexion, the patient is a good candidate for non-operative management.

MRI

Not routinely required for acute ruptures.

• Indications: Diagnostic uncertainty, chronic ruptures (>4 weeks) to assess retraction and muscle atrophy, or preoperative planning for reconstruction.
• Findings: T2 hyperintensity, retraction measurement, fatty infiltration of muscle (Goutallier stage).

Visual Element: Side-by-side MRI images showing a normal Achilles tendon and an acute rupture with significant retraction and hematoma.

Classification

By Anatomic Location

1. Type 1: Musculotendinous junction.
2. Type 2: Mid-substance (Watershed area) - Most common.
3. Type 3: Insertional (avulsion).

By Chronicity

• Acute: < 4 weeks.
• Chronic (Neglected): > 4 weeks. Characterized by retraction, scarring, and muscle atrophy.

Treatment: The Great Debate

Operative vs Non-Operative

Historically, surgery was preferred to reduce re-rupture rates. However, modern "Functional Rehabilitation" has changed the landscape.

The Evidence Corner:

• Soroceanu Meta-analysis (2012): Showed that if functional rehab is used, re-rupture rates are statistically similar between operative (3.5%) and non-operative (3.9%) groups.
• PROMIS Trial (UK, 2020): Large multi-center RCT. Found no difference in ATRS (Achilles Tendon Rupture Score) at 1 year. Non-operative group had slightly more re-ruptures, but surgical group had nerve injuries and infections.

Decision Algorithm

Who gets Surgery?

1. High-Level Athletes: To maximize push-off power and minimize even a small risk of re-rupture.
2. The "Gap" Patients: If ultrasound shows the tendon ends do not meet even in full plantarflexion.
3. Delayed Presentation: If the gap has filled with scar tissue in an elongated position.
4. Patient Preference: Some patients accept surgical risks to avoid the uncertainty of re-rupture.

Who gets Non-Operative?

1. Most Recreational Patients: If the gap closes on ultrasound.
2. Comorbidities: Diabetes, smoking, poor skin, vascular disease (High risk of wound complications).
3. Sedentary/Low Demand.

Management Protocols

Non-Operative (Functional Rehab)

1. Week 0-2: Cast or Fixed Boot in full equinus (30°). Non-weight bearing.
2. Week 2-4: CAM Boot with wedges (approx 20°). Weight-bearing as tolerated.
3. Week 4-8: Remove wedges gradually (1 wedge every week). Full weight bearing.
4. Week 8-12: Wean out of boot into shoe with heel lift. Start strengthening.
5. Month 3-6: Sport-specific rehab. No explosive sports until >6 months.

Operative Techniques

1. Open Repair: Longitudinal medial incision. Modified Kessler or Krackow locking sutures. Epitendinous suture to smooth the repair.
   • Risk: Wound breakdown, superficial nerve injury.
2. Minimally Invasive (Percutaneous): Mini-incisions with distinct instrumentation (e.g., Achillon, PARS).
   • Risk: Sural nerve entrapment (highest risk), but better cosmesis and wound healing.

Visual Element: Illustrations demonstrating the Krackow locking stitch technique and the path of the Sural nerve relative to the lateral border of the tendon.

Complications

Surgical

• Wound Infection/Dehiscence: The disaster case. The skin is thin and vascularity is poor. Can lead to free flaps.
• Sural Nerve Injury: Causes numbness on lateral foot.
• DVT/PE: High risk due to immobilization. Chemical prophylaxis is controversial but often used.

Non-Operative

• Re-rupture: The primary concern.
• Elongation: Heals "long," leading to weakness in push-off (calf pump failure).
• Atrophy: Calf circumference rarely returns to normal.

Special Situation: Chronic Rupture

If a patient presents 3 months late, the tendon ends are retracted and the muscle is fatty. You cannot just sew it back together.

• Techniques:
  • V-Y Advancement: Lengthening the fascial turndown.
  • FHL Transfer (Flexor Hallucis Longus): The gold standard for reconstruction. The FHL is harvested and tenodesed to the calcaneus. It acts as a vascularized graft and a motor unit.
  • Allograft: Rarely used due to cost and infection risk.

Exam Tips for FRACS

• Viva Scenario: "40-year-old male, weekend basketball, acute pop."
• Key Phrase: "I would discuss the risks and benefits of both options, citing the PROMIS trial."
• Don't Forget: Assess the skin condition and smoking status immediately. These are absolute contraindications to surgery in many hands.
• Rehab: Be able to recite a specific functional protocol. "Cast for 2 weeks, then boot..." shows you are safe.

Summary

The management of Achilles ruptures is a balance between biology (healing) and mechanics (tension). Whether you cut or cast, the goal is a tendon that is healed at the correct length to restore the length-tension relationship of the triceps surae.

Related Topics:

• Achilles Tendinopathy
• FHL Transfer Technique
• Peroneal Tendon Disorders
• Ankle Fractures