American Society of Hirudotherapy

A systematic review and meta-analysis of medical leech therapy for osteoarthritis of the knee

Lauche R, Cramer H, Langhorst J, Dobos G (2014) · The Clinical Journal of Pain · n=237

RCT evidence detailTrial reference
GRADE ModerateRCTCondition: Knee Osteoarthritis →
Sample size of this trial compared with other Knee Osteoarthritis trialsWang H 2018264Lauche R 2025240Lauche R 2014237Lauche R 2014237Farzali S 2025181Cui Y 2024144Andereya S 2008113Andereya S 2008113Isik M 201790Khoshnevisan A 202280
This trial (highlighted) by sample size alongside other indexed Knee Osteoarthritis trials. Larger trials generally carry more statistical weight.

Study Profile

Design
systematic review and meta-analysis of randomized (3 RCTs) and nonrandomized (1 CCT) controlled trials
Sample size (n)
237
Intervention
Medical leech therapy as delivered in the included knee-osteoarthritis trials
Comparator
Control conditions of the included trials (topical NSAID, TENS, sham/placebo)
Primary endpoint
Pain, functional impairment, and joint stiffness (standardized mean differences with 95% CI)
Primary result
Strong evidence for immediate (SMD -1.05, P<0.01) and short-term pain reduction (SMD -1.00, P<0.01); immediate improvement in physical function (SMD -0.72, P<0.01); immediate (SMD -0.88, P=0.04) and long-term joint-stiffness improvement (SMD -0.62, P<0.01); moderate evidence for short-term function (SMD -0.46) and long-term pain (SMD -0.45)
Effect size (Cohen's d)
1.05
Follow-up duration
per included trials (immediate to long-term windows)
PMID
23446069

Key Findings

  • Three RCTs and one CCT pooled (237 patients); three trials rated low risk of bias
  • Strong evidence for immediate (SMD -1.05) and short-term (SMD -1.00) pain reduction
  • Immediate improvement in physical function (SMD -0.72) and joint stiffness (SMD -0.88)
  • Long-term improvements in stiffness (SMD -0.62) and pain (SMD -0.45)
  • No serious adverse events reported across the included trials

Limitations

  • Only four controlled trials existed as of the August 2012 search
  • Included trials were open-label; no blinded sham comparison available
  • Authors call for further high-quality RCTs before conclusive judgment

Clinical Implications

This meta-analysis aggregates Michalsen 2003, Andereya 2008, and the other controlled knee-OA data into pooled effect sizes, providing the quantitative backbone for the moderate-evidence grading of leech therapy in knee osteoarthritis. It adds no new trial cohort of its own.

Related Trials

Effectiveness of leech therapy in osteoarthritis of the knee: a randomized, controlled trial

Michalsen A, Klotz S, Lüdtke R, Moebus S, Spahn G, Dobos GJ (2003)

Leech therapy for symptomatic treatment of knee osteoarthritis: results and implications of a pilot study

Andereya S, Stanzel S, Maus U, Mueller-Rath R, Mumme T, Miltner O (2006)

Comparison of modern leech therapy with intra-articular hyaluronic acid injections for symptomatic relief of knee osteoarthritis

Andereya S, Stanzel S, Maus U, Mueller-Rath R, Mumme T, Miltner O, Andereya S (2008)

Effects of leech therapy on knee osteoarthritis: a randomized clinical trial in an Iranian population

Khoshnevisan A, Sahebkar A, Mohammadpour AH, Mosaffa-Jahromi M (2022)

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This website provides educational information and does not constitute medical advice, diagnosis, or treatment recommendations. Medicinal leech therapy carries clinically meaningful risks and should be performed only by qualified clinicians under institutionally approved protocols. FDA 510(k) clearance for medicinal leeches is limited to specific indications; investigational and off-label discussions are labeled accordingly. For patient-specific guidance, consult a qualified healthcare provider.