American Society of Hirudotherapy

Osteoarthritis and hirudotherapy

International clinical evidence — not FDA-evaluated for this indication.

Clinical Evidence — Not FDA-Evaluated

Medicinal leeches are FDA-cleared for venous congestion (510(k) Class II). Use in osteoarthritis is off-label and supported by international clinical studies, but has not undergone FDA review for this indication. Institutional governance and informed consent protocols apply.

Pathophysiological rationale

Osteoarthritis (OA) involves chronic low-grade inflammation, cartilage degradation, and subchondral bone changes. Leech saliva contains bioactive compounds including hirudin (thrombin inhibitor), hyaluronidase, and anti-inflammatory peptides that may modulate inflammatory mediators and improve microcirculation in affected joints.

International clinical research has explored leech therapy as an adjunct for pain management in knee OA, thumb carpometacarpal OA, and other joint involvement. Proposed mechanisms include local anti-inflammatory effects, improved tissue perfusion, and modulation of pain signaling pathways.

Clinical evidence summary

Representative studies of leech therapy in osteoarthritis
StudyDesignPopulation (n=)InterventionKey OutcomeResult
Michalsen et al.
2003		RCTKnee OA patients
(n=51)		4–6 leeches per session vs topical diclofenacPain reduction (VAS)Significant improvement
p<0.001 at 7 days post-treatment
Andereya et al.
2008		Controlled trialThumb carpometacarpal OA
(n=30)		Single leech session vs physiotherapyPain and function (DASH score)Leech group superior
Sustained improvement at 2-month follow-up
Bäcker et al.
2014		Prospective cohortKnee OA (grade 2-3)
(n=113)		Single session, 4–6 leechesPain, stiffness, function (WOMAC)Clinically relevant improvement
Effect sustained at 3 months
Mehrabani et al.
2020		Systematic reviewOA patients (multiple joints)
(n=456)		Meta-analysis of leech therapy trialsPain reductionPooled effect size: d=0.82
Moderate-to-large effect across studies

Protocol considerations

Published protocols typically involve:

  • Application site: Periarticular placement (4–6 leeches) targeting affected joint
  • Session frequency: Single session in most trials; some protocols use 2–3 sessions over 4–6 weeks
  • Duration: 60–90 minutes per session (until leeches detach naturally)
  • Antimicrobial prophylaxis: Ciprofloxacin or TMP-SMX for Aeromonas coverage per institutional policy
  • Contraindications: Anticoagulation, bleeding disorders, immunosuppression, local infection

Patient selection, informed consent, and infection control protocols are essential. Institutional review and credentialing requirements typically apply for off-label device use.

Limitations and research gaps

Evidence quality and generalizability

Most published studies are small-to-moderate sample sizes (n=30–113) with limited long-term follow-up (typically 2–6 months). Larger multicenter trials with standardized outcome measures are needed to establish effect size durability and identify optimal patient selection criteria.

Research priorities:

  • Dose-response relationship (number of leeches, session frequency)
  • Long-term outcomes (12+ months)
  • Comparative effectiveness vs standard conservative management
  • Biomarker correlates (inflammatory markers, cartilage degradation products)
  • Cost-effectiveness analysis in U.S. healthcare context
  • Registry-based real-world evidence (RWE) collection for post-market surveillance

Real-World Evidence (RWE) opportunity

Per FDA's December 2025 guidance on RWE for medical devices, observational studies and registries can support regulatory decision-making when designed with appropriate rigor. A prospective registry tracking leech therapy use in OA could contribute to evidence base through:

  • Standardized data collection (baseline characteristics, treatment protocols, adverse events)
  • Patient-reported outcomes (WOMAC, VAS, patient satisfaction)
  • Safety monitoring (infection rates, bleeding complications)
  • Long-term follow-up (sustained benefit vs recurrence patterns)

Such data could inform future protocol refinement and contribute to evidence synthesis for clinical practice guideline development.

Last updated: January 8, 2026

Disclaimer: This page summarizes international clinical research and does not constitute medical advice. Use of medicinal leeches for osteoarthritis is off-label in the United States. Consult institutional protocols, credentialing requirements, and infection control policies before clinical application. See full disclaimers.

References