Medically reviewed by Dr. Tom Biernacki, DPM
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Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Township, MI
Last reviewed: May 2026
| Feature | Achilles Tendinitis | Achilles Tendinosis | Achilles Tendinopathy (umbrella term) |
|---|---|---|---|
| Pathology | Acute inflammatory response; neutrophil/prostaglandin mediated | Chronic collagen disorganization; no inflammatory cells on biopsy | Clinical diagnosis covering both |
| Duration | Less than 6 weeks | Greater than 6-12 weeks | Variable |
| MRI Finding | Peritendinous edema; fusiform swelling | Intrasubstance signal change; mucoid degeneration; no edema | Thickening 6mm+ (normal 4-6mm) |
| Response to NSAIDs | Good (anti-inflammatory benefit) | Poor (no inflammation to target) | Variable |
| Best treatment | Rest, ice, NSAIDs, eccentric loading | Eccentric loading, ESWT, collagen synthesis support | Eccentric loading is cornerstone of both |
| Rupture risk | Low if treated | Higher; degenerated collagen is mechanically weak | Elevated with chronic tendinosis + fluoroquinolone use |
| Treatment | Evidence Level | Mechanism | Protocol | Success Rate |
|---|---|---|---|---|
| Eccentric loading (Alfredson protocol) | Level I | Stimulates collagen remodeling; mechanotransduction | 3×15 reps twice daily x 12 weeks; off a step | 60-90% non-insertional; less effective insertional |
| Heavy slow resistance (HSR) | Level I | Equal to eccentric; better tolerated | 3×15 reps, slow tempo, 3x/week x 12 weeks | Non-inferior to eccentric; preferred for insertional |
| Extracorporeal shockwave (ESWT) | Level I | Neovascularization; collagen synthesis; analgesic | 3-5 weekly sessions | 65-80% improvement in chronic tendinosis |
| PRP injection | Level II | Growth factor delivery; collagen scaffold | 1-3 injections under ultrasound guidance | Evidence mixed; may benefit refractory cases |
| Heel lift / orthotic | Level III | Reduces Achilles load; corrects pronation | Full-time 6-12 weeks; then transition out | Adjunct; reduces acute pain; addresses biomechanics |
| Surgery (debridement/repair) | Level II-III | Removes degenerated tissue; promotes healing | Reserved for failed 6-12 months conservative | 70-85% return to sport; 3-6 month recovery |
Achilles tendinitis (acute inflammation) and tendinosis (chronic degeneration) need completely different treatments — and most chronic Achilles pain is actually tendinosis being treated as if it were tendinitis.
You’re in the right place. Dr. Tom Biernacki, DPM, FACFAS — board-certified foot & ankle surgeon with 3,000+ surgeries — explains exactly what Achilles tendinitis vs tendinosis means and what works. Call (810) 206-1402 for same-day appointment at Howell or Bloomfield Township.
Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Watch: Achilles Tendonitis & Back of Heel Pain [BEST Home Treatments 2024!] — MichiganFootDoctors YouTube
The term Achilles tendinitis is frequently misapplied to any Achilles pain—but the distinction between true tendinitis and tendinosis is not merely semantic. The two conditions have completely different underlying pathology and require fundamentally different treatment approaches. Applying the wrong treatment to the wrong diagnosis explains why many Achilles patients don’t improve.
The most important clinical decision with Achilles Tendinitis Vs Tendinosis Treatment isn’t which treatment to start with — it’s identifying the correct subtype. That changes everything. Call (810) 206-1402.
The most important clinical decision with Achilles Tendinitis Vs Tendinosis Treatment isn’t which treatment to start with — it’s identifying the correct subtype. That changes everything. Call (810) 206-1402.
Achilles Tendinitis: Acute Inflammatory Phase
Tendinitis (true inflammation) occurs in the acute phase: within the first 2-6 weeks of Achilles pain. Histologically, there is actual inflammatory cell infiltration of the tendon and peritenon. Characteristics: acute onset, tenderness along the tendon, warmth and swelling, stiffness with rest. Treatment: relative rest, ice, NSAIDs for the inflammatory phase, gentle stretching. Anti-inflammatory treatment IS appropriate for true tendinitis.
Achilles Tendinosis: Chronic Degenerative Change
Tendinosis occurs when acute tendinitis fails to resolve (or is never properly treated) and the tendon undergoes degenerative change: collagen fiber disorganization, failed healing response, and angiofibroblastic hyperplasia without inflammatory cells. Histologically: NO inflammation is present. Characteristics: chronic onset (weeks to months), thickened tendon with nodularity, stiffness improving with warm-up, pain during activity. Anti-inflammatory drugs and rest are largely ineffective for tendinosis.
Evidence-Based Treatment for Tendinosis: Eccentric Loading
The Alfredson Eccentric Protocol is the gold standard for Achilles tendinosis: standing on the edge of a step, raise up on both feet, then lower down slowly on the affected foot only—3 sets of 15 repetitions, twice daily, 12 weeks. This controlled tendon loading stimulates collagen remodeling and neovascularization. Success rate: 60-90% in non-insertional tendinosis. This program must continue even through mild pain—discomfort during eccentric loading is expected and acceptable.
Advanced Treatments When Eccentric Loading Fails
PRP injection: platelet-rich plasma delivers concentrated growth factors to stimulate collagen remodeling—particularly effective for midportion tendinosis. ESWT: focused or radial shockwave stimulates healing in chronic tendinosis. Surgical debridement: stripping degenerative tissue from the tendon core—reserved for cases failing 6+ months of all conservative measures.
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PowerStep Pinnacle Insoles
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Heel-lifting arch support that reduces Achilles tension during treatment—especially important for insertional Achilles tendinopathy.
Dr. Tom says: “Reducing Achilles tension with a heel lift is one of the most effective conservative interventions for Achilles problems.”
Achilles tendinopathy, heel cord tension reduction, daily support
Acute tendon rupture (requires immobilization)
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Doctor Hoy’s Natural Pain Relief Gel
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Natural topical analgesic for Achilles tendon pain—helps manage discomfort during the eccentric loading rehabilitation program.
Dr. Tom says: “Useful for managing soreness during the Alfredson protocol. The tendon should hurt during eccentric loading—this helps make it tolerable.”
Eccentric loading soreness management, tendinopathy pain
Acute rupture or open wound
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✅ Pros / Benefits
- Accurate tendinitis vs. tendinosis diagnosis guides correct treatment
- Alfredson eccentric protocol instruction
- PRP injection for stubborn tendinosis
- ESWT for refractory cases
- Surgical debridement as last resort
❌ Cons / Risks
- Alfredson protocol requires 12 weeks of consistent daily exercise
- Tendinosis recovery is measured in months, not weeks
Dr. Tom Biernacki’s Recommendation
Most of my Achilles patients have been diagnosed with ‘tendinitis’ and treated with rest and anti-inflammatories for months—with no improvement. That’s because most chronic Achilles pain is tendinosis, not tendinitis. Inflammation isn’t the problem; degeneration is. The treatment is not rest—it’s controlled loading through eccentric exercise. This is one of the most common treatment errors I see in practice.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
How do I know if I have tendinitis or tendinosis?
Duration is the key: tendinitis is acute (weeks), tendinosis is chronic (months+). Ultrasound or MRI can definitively differentiate by showing inflammatory vs. degenerative changes.
Should I rest Achilles tendinosis?
No—rest does not heal tendinosis. Controlled eccentric loading (Alfredson protocol) is the evidence-based treatment. Complete rest allows the degeneration to persist.
How long does Alfredson eccentric protocol take?
12 weeks of twice-daily eccentric exercises. Most patients notice significant improvement by weeks 6-8.
What is insertional vs. non-insertional Achilles tendinopathy?
Insertional (at the heel bone attachment) is more common in sedentary patients and responds differently to treatment. Non-insertional (2-6cm above insertion) is the classic runners’ tendinopathy and responds best to eccentric loading.
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Dr. Tom Biernacki, DPM is a board-certified foot & ankle surgeon (ABFAS & ABPM) at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has made him one of the most-followed foot & ankle educators on YouTube.