What is tendinosis?

Tendinosis Definition and Management

Tendinosis is a degenerative condition of tendons characterized by disorganized collagen fibers, increased mucoid ground substance, abnormal neovascularization, and the absence of inflammatory cells, representing a failed healing response rather than an inflammatory process. 1

Pathophysiology of Tendinosis

Tendinosis differs significantly from tendinitis in several key ways:

• Structural changes:

  • Disorganized and discontinuous collagen fibers that lack normal reflectivity under polarized light
  • Increased mucoid ground substance (extracellular matrix)
  • Abnormal cellular proliferation with fibroblastic or myofibroblastic appearance
  • Prominent capillary proliferation and neovascularization
  • Fibrocartilaginous metaplasia with chondroid-appearing tenocytes 1

• Key distinguishing feature:

  • Complete absence of inflammatory cells, confirming this is a degenerative rather than inflammatory condition 2, 1

• Macroscopic appearance:

  • Healthy tendons appear glistening white
  • Tendinotic tendons appear grey and amorphous 1

Etiology and Risk Factors

Tendinosis develops through a complex interplay of factors:

• Repetitive mechanical loading/overuse
• Genetic variants of matrix proteins
• Metabolic disorders
• Failed healing response
• Pathological vessel and sensory nerve ingrowth that contributes to pain signaling 3

Management Approach

The American College of Radiology recommends a stepwise approach for tendon issues:

1. First-line conservative management:

   • Rest and activity modification
   • NSAIDs for short-term pain relief only (e.g., naproxen 500mg twice daily)
   • Physical therapy with emphasis on eccentric strengthening exercises
   • Functional bracing while avoiding complete immobilization 4

2. Phased rehabilitation approach:

   • Initial phase (0-4 weeks): Pain control and protected range of motion
   • Intermediate phase (4-8 weeks): Progressive strengthening and eccentric training
   • Advanced phase (8-12 weeks): Occupation-specific training and functional exercises 4

3. Injection therapy:

   • Corticosteroid injections should be used judiciously (limited to 2-3 injections)
   • Must be performed with proper aseptic technique in appropriate settings
   • Post-injection care includes avoiding overuse of the injected area for 24 hours 4

4. Surgical intervention:

   • Reserved only for cases that fail 3-6 months of well-managed conservative treatment 4

Evidence-Based Treatment Efficacy

Current evidence supports:

• Strongest evidence: Eccentric exercise has the most robust evidence for effectiveness 2, 3
• Mixed evidence: Extracorporeal shock wave therapy shows variable results 2, 3
• Limited evidence: Sclerosing injections, nitric oxide patches, and platelet-rich plasma injections show promising early results but require further study 2, 5
• Not effective: Traditional anti-inflammatory treatments (NSAIDs and corticosteroids) provide only short-term relief and may potentially interfere with proper healing 2, 5, 3

Common Pitfalls in Management

1. Misdiagnosis as tendinitis: Treating tendinosis as an inflammatory condition with prolonged anti-inflammatory medications may delay appropriate treatment 1

2. Inadequate rehabilitation: Failing to complete a full eccentric strengthening program is a common reason for treatment failure 4, 3

3. Premature return to activity: Recovery takes time, and returning to full activity should only occur when the patient demonstrates:

   • Complete resolution of pain
   • Full range of motion
   • Strength symmetry >90% compared to the uninjured side
   • Successful completion of occupation-specific functional tests 4

4. Overreliance on passive treatments: Focusing on passive modalities rather than active rehabilitation can lead to poor outcomes 4, 3