The Debit Side of Stem-Cell Joint Injections

A Prospective Cohort Study

James W. Pritchett, MD


Curr Orthop Pract. 2021;32(2):118-123. 

In This Article

Abstract and Introduction


Background: There is little long-term information and no prior report that used independently collected data describing the effectiveness and complications of intraarticular injections of stem cells.

Methods: This study reviewed the records of 2964 patients who received stem-cell injections in the hip, knee, or shoulder and 2971 patients who had injections of steroids or viscosupplementation (comparison group).

Results: Pain improved initially in 2104 (71%) of patients who received stem cells. At a mean follow-up of 5.6 yr, 563 (15%) patients continued to report less pain, and the mean time of pain reduction was 17 mo (range, 1 to 84 mo). The mean cost of stem-cell care was $6000 (range, $1200 to $13,000). There were 115 (8%) complications using autologous stem cells, 113 (8%) with donor cells, and 13 (9%) when both were used. Stem-cell complications included six tumors, 14 infections, 48 syncopal, arrhythmia, seizure, or vasovagal reactions, 42 chronic culture-negative effusions, 18 injection site rashes, 44 instances of systemic viral like syndrome or herpes zoster-like reactions, 31 new allergies, and 39 instances of acute and severe worsening of pain and function. There were 82 hospitalizations. For the comparison group, there were 61 (2%) complications and eight hospitalizations.

Conclusions: The frequency (8%) and severity of complications with stem cell-injections is higher than for steroid or viscosupplementation injections (2%). Stem-cell joint injections are a costly and speculative treatment and should only be used with a deep understanding of the risk. Practitioners providing stem cell joint injections must include long-term follow-up as part of their care. Additional validated scientific studies are needed.

Level of Evidence: Level II.


Stem-cell infusions were first reported in 1951 for treatment of bone marrow aplasia resulting from accidental radiation exposure and aplastic anemia after chemotherapy.[1] The stem cells were obtained from volunteer donors, cadavers, or feti. Stem-cell infusions were unsuccessful at first because of rejection, except for a few patients whose identical twins were donors.[2–4] In 1970, E. Donnall Thomas, MD reported the first successful bone marrow rescue using a bone-marrow allograft. The patient had leukemia and had been treated with whole-body irradiation.[5] The Thomas laboratory was then at Seattle's Providence Hospital. Drs. Sauvage and Dedomenico performed their initial experiments with coronary artery bypass grafting in dogs in an adjacent laboratory.[6] The Thomas and Sauvage laboratories sometimes shared dogs.[6] Marrow-derived stem cells were infused both intravenously and, occasionally, intraarticularly in both dogs and patients for joint pain that was experienced during their experimental treatments.[3,4,7,8] The joint symptoms usually improved.[2] Dr. Thomas won the Nobel Prize in 1990 for his stem-cell research.[9]

There are many published reports of remarkably good results from injecting stem cells into joints, tendons, and other tissues.[10–16] The superiority of stem-cell injections over other treatments in providing freedom from pain and restoring range of motion and function has been reported in many journals. Regeneration of cartilage and tendons has been claimed but not proven.[11,15–18] There are no completed clinical trials translating cellular therapies from Phase I/IIa first-in-man studies through Phase III documenting regeneration of articular cartilage. Complications can be difficult to identify because they may take years to develop. Some complications are not immediately apparent to the patient or are not reported or understood by the treating practitioner. Despite the absence of compelling evidence from clinical trials, some physicians assert that stem cells have a unique capacity to restore tissue health because they can sense their environment and differentiate in a manner that repairs the tissue defect. It is also argued that conducting controlled trials is too complex except for industrial sponsors and that waiting for results of studies denies patients the benefits they need now. Advocates claim that broad use of stem cells in clinical practice should be allowed and encouraged until evidence regarding efficacy is gathered. The stem-cell therapies in current use have been described as unproven.[19] Proponents generally assert that stem-cell therapies are quite safe, particularly when the cells are autologous.[11,15,18,20,21] The demand for stem-cell therapies in orthopaedics is driven by the limited effectiveness of treatments for osteoarthritis. Patients are interested in a treatment that does not involve joint replacement.

The questions asked in this study were: What are the nature and frequency of complications from stem-cell injections? Are stem-cell complications recognized by the same practitioners that provide the injections? Are stem-cell injection complications serious, and do they require additional treatment? Do stem-cell injections reduce pain and for what duration? The hypothesis of this study was that the safety and efficacy of stem-cell injections may not match the claims and expectations of patients and their treating physicians.