Is there a new injectable gel for knee osteoarthritis that can heal cartilage more effectively?

Injectable Treatments for Knee Osteoarthritis: Current Evidence on Cartilage Healing

Currently, there is no injectable gel treatment for knee osteoarthritis that has been conclusively proven to heal cartilage, though hyaluronic acid injections may provide symptomatic relief with limited structural benefits. 1

Current Injectable Options for Knee OA

Hyaluronic Acid Injections (Viscosupplementation)

• Mechanism: Supplements synovial fluid with hyaluronic acid to improve lubrication and potentially provide anti-inflammatory effects
• Efficacy:
  • Limited clinical benefit with a number needed to treat of 17 patients 1
  • Effect size approaches zero when limited to trials with low risk of bias 1
  • May provide pain relief for up to 6 months, with slower onset but potentially longer duration than corticosteroid injections 1
  • Higher molecular weight products may provide better pain relief than lower molecular weight preparations 1

Corticosteroid Injections

• Recommendation: More strongly supported by evidence than hyaluronic acid for short-term pain relief 1
• Indication: Recommended for persistent pain inadequately relieved by other interventions 2
• Efficacy: Provides better short-term relief compared to viscosupplementation 1
• Best for: Acute exacerbation of knee pain, especially if accompanied by effusion 2

When to Consider Injectable Treatments

Treatment Algorithm

1. First-line treatments:

   • Self-management programs including exercise and weight loss 2
   • Physical therapy as part of comprehensive management 2
   • Topical NSAIDs (strong recommendation) 2
   • Topical capsaicin (weak recommendation) 2
   • Acetaminophen and/or oral NSAIDs 2

2. Second-line treatments:

   • Intra-articular corticosteroid injections for persistent pain 2
   • Duloxetine as alternative or adjunctive therapy 2

3. Third-line or conditional treatments:

   • Hyaluronic acid injections may be considered when patients have failed:
     • Non-pharmacologic therapies
     • Topical and oral NSAIDs
     • Intra-articular corticosteroid injections 1

Patient Selection for Hyaluronic Acid Injections

Best results are seen in:

• Patients with mild to moderate knee OA 1
• Those without active joint effusion at baseline 1
• Patients over 60 years with functional impairment 1

Administration of Hyaluronic Acid

• Typically administered as 3-5 weekly injections 1
• Common formulations range from 20-48 mg per injection 1
• Repeat courses may be considered after 6 months if beneficial 1

Limitations and Caveats

• Both the American Academy of Orthopaedic Surgeons and American College of Rheumatology provide moderate strength recommendations against routine use of hyaluronic acid injections due to limited clinical benefit 1
• Hyaluronic acid may possess structure modification properties, but more studies using standardized methodology are required 2
• The effect size is relatively small, suitable patients are not well defined, and pharmacoeconomic aspects are not well established 2
• Patients with severe osteoarthritis or active inflammation/effusion may experience less benefit 1

Future Considerations

For patients with refractory pain associated with disability and radiological deterioration, joint replacement should be considered rather than continuing with injectable therapies 2

While research continues into cartilage-healing treatments, current injectable options primarily provide symptomatic relief rather than disease modification or cartilage regeneration. The clinical relevance of any structural effect of symptomatic slow-acting drugs for osteoarthritis (including hyaluronic acid) requires further evaluation 2.