ACHILLES TENDINOPATHY
Degenerative Tendinosis | Insertional vs Mid-Portion | Eccentric Loading | FHL Transfer
LOCATION-BASED CLASSIFICATION
Critical Must-Knows
- Degenerative tendinosis - NOT tendinitis (minimal inflammation)
- Watershed zone 2-6cm proximal to insertion has poorest blood supply
- Eccentric exercises are first-line (Alfredson: 2x15 reps, twice daily, 12 weeks)
- Steroids contraindicated - increased rupture risk
- FHL transfer if debriding more than 50% of tendon cross-section
Examiner's Pearls
- "Neovascularization with nerve ingrowth causes pain
- "Arc sign: pain moves with ankle dorsiflexion in mid-portion disease
- "Thompson test normal (rules out complete rupture)
- "Insertional disease has worse prognosis than mid-portion
Clinical Imaging
Imaging Gallery
Critical Achilles Tendinopathy Exam Points
Tendinosis NOT Tendinitis
Failed healing response with disordered collagen (Type I replaced by Type III), mucoid degeneration, and neovascularization with nerve ingrowth. Minimal inflammatory cells present. This is why NSAIDs have limited benefit.
Location Matters
Mid-portion (2-6cm): Watershed zone, better prognosis with eccentric exercises. Insertional: Often associated with Haglund deformity and retrocalcaneal bursitis, responds less well to conservative treatment.
Steroid Contraindication
Never inject corticosteroids into or around the Achilles tendon. Associated with tendon rupture risk. Peritendinous injections may cause skin atrophy and have limited benefit.
Surgical Threshold
Surgical debridement for refractory cases after 6 months conservative treatment. If more than 50% tendon debridement needed, augment with FHL transfer. Gastrocnemius recession if equinus contracture.
Achilles Tendinopathy At a Glance
| Parameter | Mid-Portion (Non-insertional) | Insertional |
|---|---|---|
| Location | 2-6cm proximal to insertion | At calcaneal attachment |
| Incidence | 55-65% of cases | 20-25% of cases |
| Pathology | Tendinosis in watershed zone | Enthesopathy, often with Haglund |
| Arc sign | Positive (pain moves with ankle) | Negative (pain fixed at insertion) |
| Conservative success | 70-90% | 50-60% |
| Eccentric exercises | Highly effective | Less effective, may exacerbate |
| Surgical approach | Medial or posterior midline | Central tendon-splitting |
| Augmentation | FHL transfer if more than 50% debridement | Suture anchor repair, FHL rarely needed |
TENDON - Pathophysiology
Memory Hook:TENDON reminds you this is degenerative disease with vascular and nerve changes, not acute inflammation
ALFREDSON - Eccentric Protocol
Memory Hook:Remember the ALFREDSON protocol creator - 2x15 reps, twice daily, 12 weeks
DEBRIDE - Surgical Indications
Memory Hook:DEBRIDE when conservative treatment fails after proper duration
50% Rule for FHL Transfer
Memory Hook:More than 50% tendon debridement = FHL transfer for augmentation
Overview and Epidemiology
Achilles tendinopathy is a degenerative overuse condition affecting the body's largest and strongest tendon. It represents a spectrum of tendon pathology from early reactive change to advanced degenerative disease.
Key epidemiological features:
- Running athletes: 6-18% lifetime incidence
- Jumping sports: Basketball, volleyball, tennis at higher risk
- Age distribution: Peak 30-50 years, but can occur at any age
- Bilateral involvement: 30% of cases
Risk factors:
- Training errors (rapid increase in intensity/duration)
- Biomechanical factors (hindfoot varus/valgus, equinus contracture)
- Fluoroquinolone antibiotics (10-fold increased risk)
- Systemic conditions (diabetes, obesity, hypercholesterolemia)
- Footwear changes
- Male gender (for rupture, not tendinopathy)
Terminology Matters
Use "tendinopathy" as the clinical diagnosis when symptoms and examination suggest tendon pathology. "Tendinosis" refers to the histological finding of degenerative change without inflammation. "Tendinitis" implies inflammation which is rarely the primary process.
Pathophysiology and Mechanisms
The Achilles tendon is formed by the confluence of the gastrocnemius and soleus tendons approximately 15cm proximal to its insertion on the posterior calcaneal tuberosity.
Structural anatomy:
- Length: Approximately 15cm from musculotendinous junction to insertion
- Width: 6-8cm at musculotendinous junction, narrowing to 1.5-2cm at insertion
- Rotation: Fibers rotate 90 degrees along length (lateral gastrocnemius inserts posteromedially)
- Paratenon: Loose connective tissue sheath without synovial lining
- Cross-sectional area: Approximately 60-80 mm²
Blood supply (critical for understanding pathology):
- Proximal: Muscular branches from gastrocnemius and soleus
- Middle (watershed zone): Peritendinous vessels - relatively hypovascular
- Distal: Calcaneal vessels via osseous insertion
Watershed Zone
The zone 2-6cm proximal to insertion has the poorest blood supply and is where most mid-portion tendinopathy occurs. This relative hypovascularity contributes to impaired healing and is the target zone for eccentric exercise therapy.
Biomechanics:
- Forces during running: 6-8x body weight
- Elongation: 6-8% during normal gait
- Storage of elastic energy: 35% of energy during running stored in Achilles
- Gastrocnemius: Primarily ankle plantarflexion, active with knee extended
- Soleus: Plantarflexion active regardless of knee position
Associated structures:
- Retrocalcaneal bursa: Between tendon and calcaneus (inflamed in insertional disease)
- Haglund deformity: Posterosuperior calcaneal prominence causing impingement
- Kager's fat pad: Pre-Achilles fat triangle (obliterated in rupture)
- Plantaris tendon: Runs medial to Achilles, may contribute to medial symptoms
Classification Systems
Primary Classification (Clinically Most Useful)
| Type | Location | Key Features | Prognosis |
|---|---|---|---|
| Non-insertional (Mid-portion) | 2-6cm from insertion | Watershed zone, fusiform thickening, positive arc sign | Better (70-90% non-op success) |
| Insertional | At calcaneal attachment | Often with Haglund, may have calcification, fixed tenderness | Worse (50-60% non-op success) |
| Paratendinopathy | Paratenon surrounding tendon | Crepitus, linear thickening on imaging, acute presentation | Good with activity modification |
Approximately 20-25% of cases have combined insertional and non-insertional disease.
Clinical Assessment
History:
- Location of pain: Mid-portion vs insertional
- Onset: Usually gradual (acute suggests paratendinopathy or rupture)
- Morning stiffness: Characteristic of tendinopathy (improves with activity)
- Activity relationship: Worse with activity, especially running and jumping
- Training history: Recent changes in intensity, duration, or footwear
- Previous treatment: Physiotherapy, injections, medications
- Risk factors: Fluoroquinolones, diabetes, systemic diseases
Examination:
Clinical Tests
| Test | Technique | Positive Finding | Significance |
|---|---|---|---|
| Palpation | Systematic palpation along tendon | Tenderness, thickening, nodules | Localizes pathology |
| Arc sign | Palpate tender area while dorsiflexing ankle | Tenderness moves with ankle motion | Mid-portion disease (positive) vs insertional (negative) |
| Thompson test | Squeeze calf with patient prone, knee flexed | No plantarflexion = positive = rupture | Must be NORMAL in tendinopathy (rules out complete rupture) |
| Single-heel raise | Rise onto toes on affected leg | Unable or painful | Functional assessment |
| Royal London Hospital test | Pain on palpation decreases with ankle dorsiflexion | Pain relief with stretch | Suggests mid-portion tendinopathy |
Arc Sign Distinction
Arc sign positive: Tenderness moves with ankle dorsiflexion indicating mid-portion disease. Arc sign negative: Fixed tenderness at insertion regardless of ankle position indicating insertional disease. This distinction guides treatment selection.
Biomechanical assessment:
- Hindfoot alignment (varus/valgus)
- Gastrocnemius tightness (Silfverskiold test)
- Foot posture (pronation/supination)
- Gait analysis
- Footwear assessment
Investigations
First-line imaging modality
Findings in tendinopathy:
- Tendon thickening (greater than 6mm AP diameter abnormal)
- Hypoechoic areas (degenerative regions)
- Loss of normal fibrillar pattern
- Neovascularization on Power Doppler
- Paratenon thickening in paratendinopathy
Advantages:
- Dynamic assessment
- Comparison with contralateral side
- Cost-effective
- Guides injections
- Power Doppler for neovascularization assessment
Ultrasound findings correlate well with symptoms and can guide treatment targeting areas of neovascularization.
Management Algorithm
Eccentric Exercise Protocol (Alfredson)
Protocol details:
- 2 sets of 15 repetitions
- Twice daily (morning and evening)
- 12 weeks minimum duration
- Straight knee (gastrocnemius) AND bent knee (soleus)
- Progress through moderate discomfort (pain level 4-5/10)
- Add load as pain decreases
Adjunctive treatments:
- GTN patches (nitroglycerin): May improve collagen synthesis
- ESWT: 3 sessions, 2000 impulses per session
- Heel lifts: Reduce strain on tendon
- Activity modification: Reduce provocative activities temporarily
- Biomechanical correction: Orthotics if foot posture abnormal
What NOT to do:
- Corticosteroid injections (rupture risk)
- Complete rest (deloading harmful)
- Aggressive stretching acutely
Conservative treatment is more effective for mid-portion disease than insertional disease.
Surgical Technique
Approach and Positioning:
- Prone position, tourniquet at thigh
- Medial or posterior midline incision
- Medial approach preferred to protect sural nerve laterally
Steps:
Mid-Portion Debridement Steps
Make 8-10cm longitudinal incision centered on pathological area. Incise paratenon longitudinally. Identify and protect sural nerve if using lateral approach.
Identify degenerative tissue (yellow, soft, mucoid appearance). Excise all abnormal tissue with knife or curette. May need to split tendon longitudinally to access central disease.
Assess remaining tendon cross-section. If more than 50% debrided, plan FHL transfer for augmentation.
Close tendon defect with side-to-side repair if possible. Use non-absorbable suture (2-0 Ethibond or similar).
Close paratenon if possible. Layered skin closure. Apply well-padded splint in slight plantarflexion.
If gastrocnemius recession needed, perform through same or separate incision at musculotendinous junction.
Complications
Eccentric exercise complications:
- Transient increased pain (expected, should continue)
- Calf muscle soreness
- Rare: partial rupture if pre-existing weakening
Treatment failures:
- 10-30% of mid-portion cases
- 40-50% of insertional cases
- May require eventual surgery
Non-operative complications are generally minor and self-limiting.
Postoperative Care
Simple debridement (less than 50% tendon):
Rehabilitation Phases
Below-knee cast or boot. Non-weight bearing. Elevation and ice.
Weight bearing in boot. Begin gentle ROM exercises out of boot. Physiotherapy for ankle mobility.
Wean from boot. Progressive weight bearing. Begin eccentric exercises at 8 weeks. Stationary cycling.
Sport-specific rehabilitation. Running progression from week 16. Full activity 4-6 months.
Earlier rehabilitation leads to better outcomes than prolonged immobilization.
Outcomes and Prognosis
Treatment Outcomes Summary
| Treatment | Success Rate | Return to Sport | Recurrence |
|---|---|---|---|
| Eccentric exercises (mid-portion) | 70-90% | 3-6 months | 10-20% |
| Eccentric exercises (insertional) | 50-60% | 4-8 months | 20-30% |
| ESWT adjunct | +10-15% | 3-6 months | Similar to eccentric alone |
| Surgical debridement | 75-85% | 6-9 months | 5-10% |
| FHL transfer | 80-90% | 9-12 months | Less than 5% |
Prognostic factors:
Factors Affecting Outcomes
| Factor | Better Prognosis | Worse Prognosis |
|---|---|---|
| Location | Mid-portion | Insertional |
| Duration | Less than 3 months | Greater than 12 months |
| Age | Under 40 years | Over 50 years |
| Activity level | Recreational athlete | Sedentary or elite athlete |
| Compliance | Full eccentric protocol | Incomplete exercise program |
| MRI grade | Grade I-II | Grade III (partial tear) |
| Previous treatment | First presentation | Multiple failed treatments |
Long-term outcomes are generally good with appropriate treatment matching. Patient education about the chronic nature and need for sustained rehabilitation is essential.
Evidence Base
Eccentric Exercise Effectiveness
- 82% success rate with eccentric protocol
- Pain reduction from 7/10 to 2/10 average
- Effect maintained at 5-year follow-up
- Most effective for mid-portion disease
Eccentric vs Heavy Slow Resistance
- Similar clinical outcomes at 12 weeks
- Higher patient satisfaction with heavy slow resistance
- 3 sessions per week vs daily eccentric
- Both superior to wait-and-see approach
Insertional vs Non-insertional Outcomes
- 50% success insertional vs 70-90% mid-portion
- Insertional more likely to need surgery
- Eccentric exercises may exacerbate insertional symptoms
- Different treatment protocols may be needed
FHL Transfer Outcomes
- 80-90% patient satisfaction
- Minimal functional toe flexion weakness
- Brings blood supply to degenerative area
- Indicated for greater than 50% debridement
Corticosteroid Injection Risks
- Increased rupture risk with peritendinous injection
- No long-term pain reduction
- Rupture risk highest in first 4 weeks post-injection
- Should be avoided in Achilles tendinopathy
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Mid-Portion Tendinopathy
"A 35-year-old recreational runner presents with 6 months of posterior heel pain, 4cm above the heel. Pain is worse in the morning and improves with warming up. He has tried rest and NSAIDs without improvement. Examination shows fusiform thickening with tenderness that moves when you dorsiflex the ankle."
Scenario 2: Insertional Tendinopathy
"A 45-year-old woman presents with posterior heel pain at the Achilles insertion. She has a prominent posterior heel bump. Pain is worse with stairs and inclines. Previous physiotherapy with eccentric exercises made her symptoms worse. X-ray shows a Haglund deformity and retrocalcaneal spurring."
Scenario 3: Surgical Planning
"A 40-year-old athlete presents after 9 months of failed conservative treatment for mid-portion Achilles tendinopathy. MRI shows extensive fusiform thickening with high T2 signal involving approximately 60% of the tendon cross-section. He wants to return to competitive sport."
MCQ Practice Points
Watershed Zone
Q: What is the location of the watershed zone in the Achilles tendon and why is it clinically significant? A: The watershed zone is located 2-6cm proximal to the insertion. It has the poorest blood supply (peritendinous vessels only) and is where most mid-portion tendinopathy occurs.
Arc Sign Interpretation
Q: A patient has posterior heel pain. Tenderness moves distally when the ankle is dorsiflexed. What does this indicate? A: This is a positive arc sign, indicating mid-portion tendinopathy. A negative arc sign (fixed tenderness) indicates insertional disease.
Eccentric Protocol
Q: Describe the Alfredson eccentric exercise protocol for Achilles tendinopathy. A: 2 sets of 15 reps, twice daily, for 12 weeks, performed with both straight knee (gastrocnemius) AND bent knee (soleus). Patients should work through moderate pain (4-5/10).
FHL Transfer Indication
Q: When is FHL transfer indicated during Achilles debridement surgery? A: When more than 50% of the tendon requires debridement. FHL is in-phase (plantarflexor), has excellent tendon quality, and brings new blood supply.
Corticosteroid Contraindication
Q: Why are corticosteroid injections contraindicated in Achilles tendinopathy? A: Corticosteroids increase rupture risk, with highest risk in the first 4 weeks post-injection. They provide no long-term benefit for this degenerative condition.
Australian Context
Achilles tendinopathy is common in the active Australian population, with particular prevalence in running, tennis, and Australian rules football communities. The aging but active demographic contributes to increasing incidence of both insertional and non-insertional disease.
Sports Medicine Australia endorses eccentric loading protocols as first-line treatment, consistent with international evidence. Physiotherapy services for chronic tendinopathy may be accessed through Enhanced Primary Care plans in general practice settings. Surgical management is typically performed by foot and ankle subspecialists in metropolitan teaching hospitals.
Australian prescribers should be aware of the association between fluoroquinolone antibiotics and tendinopathy. The Therapeutic Goods Administration requires black box warnings on these medications highlighting tendon-related adverse effects, particularly in patients over 60 years or those taking corticosteroids.
Exam Cheat Sheet
Achilles Tendinopathy
High-Yield Exam Summary
Key Numbers
- •Watershed zone: 2-6cm from insertion
- •Eccentric protocol: 2x15 reps, twice daily, 12 weeks
- •FHL transfer: If debriding more than 50% tendon
- •Non-op success: 70-90% mid-portion, 50-60% insertional
Clinical Pearls
- •Tendinosis NOT tendinitis - degenerative, minimal inflammation
- •Arc sign positive = mid-portion (moves with dorsiflexion)
- •Arc sign negative = insertional (fixed)
- •Thompson test must be NORMAL (rules out complete rupture)
Treatment Principles
- •Eccentric exercises first-line for mid-portion
- •Insertional disease responds poorly to eccentric loading
- •NEVER inject corticosteroids - rupture risk
- •Surgery after 6 months failed conservative treatment
Surgical Points
- •Medial approach protects sural nerve
- •FHL transfer for greater than 50% debridement
- •FHL in-phase with Achilles (plantarflexor)
- •Central tendon-splitting for insertional surgery
Exam Traps
- •Steroid injection recommendation
- •Not knowing Alfredson protocol details
- •Confusing insertional and mid-portion treatment
- •Operating too early or too late