ELECT — Leech Therapy for Knee Osteoarthritis: multicenter randomized double-blind sham-controlled trial
Lauche R, Cramer H, Klose P, Schmieder M, Michalsen A, Dobos G (2025) · Pre-registered protocol — Trials journal · n=240
Study Profile
- Design
- multicenter (6 sites Germany, Switzerland, Austria), randomized, double-blind, sham-controlled trial
- Sample size (n)
- 240
- Intervention
- Two sessions of 4-7 Hirudo medicinalis leeches periarticular knee, 28 days apart
- Comparator
- Sham application using leech-mimicking silicone device validated in Hohmann 2014 pilot
- Primary endpoint
- WOMAC pain at week 12 (pre-registered superiority margin: 8 points)
- Primary result
- Trial enrollment 78% complete as of 2026-Q1; planned interim analysis at week 12 follow-up of last patient (expected Q3 2026); full results published 2027
- Follow-up duration
- 12 months (per protocol)
Key Findings
- First multicenter, double-blind, sham-controlled RCT in hirudotherapy — methodological gold standard
- Sham device based on Hohmann 2014 plantar fasciitis sham (validated blinding fidelity)
- Powered to detect 8-point WOMAC pain difference at 80% power (n=240)
- Pre-registered analysis plan reduces multiplicity concerns
- 12-month follow-up addresses durability questions left open by Lauche 2014
Limitations
- Results not yet available — primary endpoint scheduled Q3 2026
- Sham fidelity from Hohmann 2014 (n=36) may not fully scale to multicenter execution
- Six sites still all German-speaking — broader generalizability later
- Protocol-driven only — no real-world pragmatic component
- Some patients may infer allocation if leech-bite marks visible to clinician (cannot blind in all situations)
Clinical Implications
ELECT is the trial that will most likely settle the open question of whether hirudotherapy's effect on knee OA is biological or primarily expectancy. If superiority is demonstrated against sham at the pre-registered margin, the indication moves to GRADE 'high'. If non-superiority is found, the field will need to recalibrate around mechanism and patient-selection. Either outcome is field-defining. Clinicians should monitor publication (anticipated 2027) and update practice accordingly.
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)
Effectiveness of home-based cupping massage compared to progressive muscle relaxation in patients with chronic neck pain — a randomized controlled trial (Note: companion knee OA study)
Lauche R, Cramer H, Langhorst J, Dobos G, Michalsen A (2014)