American Society of Hirudotherapy

Comparison of the effectiveness of medicinal leech and TENS therapy in the treatment of primary osteoarthritis of the knee: a randomized controlled trial

Isik M, Ugur M, Yakisan RS, Sari T, Yilmaz N (2017) · Zeitschrift für Rheumatologie · n=90

RCT evidence detailTrial reference
GRADE LowCohort / case seriesCondition: Knee Osteoarthritis
Sample size of this trial compared with other Knee Osteoarthritis trialsWang H 2018264Lauche R 2025240Lauche R 2014237Farzali S 2025181Cui Y 2024144Andereya S 2008113Andereya S 2008113Sarbaev IS 201996Isik 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
single-center, prospective, randomized, single-blind, parallel-group RCT (Atatürk University, Erzurum, Turkey)
Sample size (n)
90
Intervention
Five Hirudo medicinalis leeches applied to the affected knee once weekly for 3 weeks (leech group, n=46)
Comparator
Transcutaneous electrical nerve stimulation (TENS) therapy following a standardized regimen (TENS group, n=44)
Primary endpoint
Change in pain on VAS and WOMAC scores at days 0, 21, and 180
Primary result
VAS pain score decreased similarly in both groups by day 21 (p<0.001 within-group); between-group course of change in pain similar throughout; all WOMAC subscores decreased similarly in both groups (p=0.819 between-group); long-term (day 180) benefits slightly greater in TENS arm
Follow-up duration
180 days

Key Findings

  • First RCT directly comparing leech therapy with TENS, a widely used non-pharmacologic modality for knee OA
  • Leech therapy produced statistically significant pain and function improvements equivalent to TENS at day 21
  • All WOMAC subscores (pain, stiffness, function) decreased significantly with both modalities through 180 days
  • Long-term benefits modestly favored TENS over leech therapy at the 6-month timepoint
  • Authors conclude leech therapy is a viable alternative or additional non-surgical option for knee OA

Limitations

  • Single center (Atatürk University Faculty of Medicine, Erzurum)
  • Single-blind only — patients aware of intervention
  • TENS comparator parameters not fully described in published methods
  • No NSAID arm — cannot triangulate vs. pharmacologic standard of care
  • Both groups improved significantly, making between-group inference dependent on equivalence assumptions not formally tested

Clinical Implications

Isik 2017 is the largest single-RCT of leech therapy for knee OA published outside Germany (n=90) and the first to use a non-pharmacologic comparator (TENS). The equivalence-level finding is clinically useful: for clinicians and patients choosing between leech and TENS, the trial suggests broadly similar short-term outcomes with TENS having a small long-term edge. The trial supports leech therapy as a reasonable alternative for patients who decline electrotherapy. Methodologically the lack of a pharmacologic comparator limits placement within the wider OA-treatment hierarchy, but the Turkish cohort adds geographic diversity to the European-dominated evidence base.

Related Trials

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.