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Stem cell injections in knee osteoarthritis: a systematic review of the literature
  1. Haiko IMFL Pas1,2,3,
  2. Marinus Winters4,
  3. Hidde J Haisma5,
  4. Martinus JJ Koenis6,
  5. Johannes L Tol1,3,7,
  6. Maarten H Moen1,8,9
  1. 1 Department of Sports Medicine, The Sports Physicians Group, OLVG West, Amsterdam, The Netherlands
  2. 2 Department of Orthopaedic Surgery, Academic Medical Centre, Amsterdam, The Netherlands
  3. 3 Amsterdam Center of Evidence Based Sports Medicine, Academic Medical Center, Amsterdam, The Netherlands
  4. 4 Rehabilitation and Sports Medicine Department, University Medical Centre Utrecht, Utrecht, The Netherlands
  5. 5 Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, Groningen University, Groningen, The Netherlands
  6. 6 Department of Rehabilitation Medicine, University Medical Centre Groningen, Groningen, The Netherlands
  7. 7 Aspetar, Orthopedic and Sports Medicine Hospital, Doha, Qatar
  8. 8 Department of Sports Medicine, Bergman Clinics, Naarden, The Netherlands
  9. 9 Department of Elite Sports, National Olympic Committee – Netherlands Sports Federation, Arnhem, The Netherlands
  1. Correspondence to Dr Haiko IMFL Pas, Department of Orthopaedic Surgery, Academic Medical Centre, Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands; pas.haiko{at}


Objective Stem cell injection for knee osteoarthritis (KOA) is an emerging new therapy, and we aimed to review its evidence of efficacy.

Design Systematic review.

Eligibility criteria Criteria for eligibility were randomised controlled trials (RCTs) and non-RCT on the efficacy of stem cell injections in KOA. All references were checked for missed articles.

Data sources MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Library, PEDro and SPORTDiscus were searched. A grey literature search was performed. No restrictions were imposed to our search strategy.

Risk of bias and data synthesis Risk of bias was assessed using the Cochrane risk of bias tool. Descriptive synthesis was performed using the levels of evidence according to the Oxford Levels of Evidence.

Results Five RCTs and one non-RCT were found. Bone-marrow-derived stem cells, adipose-derived mesenchymal stem cells and peripheral blood stem cells were used. All trials were at high risk of bias, resulting in level-3 evidence. All five RCTs reported superior efficacy for patient-reported outcomes (Visual Analogue Scale, Western Ontario and McMaster Universities Arthritis Index, Tegner, Lysolm, International Knee Documentation Committee, Knee Injury and Osteoarthritis Outcome Score, Lequesne) compared with controls at final follow-up (range 24–48 months). Superior radiological outcomes were found favouring stem cell injection. Superior histological outcomes and/or improved arthroscopically scored healing rates were reported in two trials. No serious adverse events were reported.

Conclusion Six trials with high risk of bias showed level-3 or level-4 evidence in favour of stem cell injections in KOA. In the absence of high-level evidence, we do not recommend stem cell therapy for KOA.

  • Cellular
  • Knee
  • Osteoarthritis

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  • Competing interests HP received a grant from the Dutch National Olympic Committee and the Sports Physicians Group, Department of Sports Medicine, OLVG West, Amsterdam for the realisation of this review. The Dutch National Olympic Committee and the Sports Physicians Group had no influence in the performance of this review. HP and MW report receiving grants from the Dutch National Olympic Committee outside the submitted work.

  • Provenance and peer review Not commissioned; externally peer reviewed.