COMMENTARY

Regenerative Medicine Landscape for Arthritis, Tendinopathies Continues to Evolve

Kathleen Davenport, MD

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November 02, 2022

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Kathleen Davenport, MD

Regenerative medicine injections have been increasingly used for many medical applications. In orthopedics, sports, and musculoskeletal medicine, tendon and joint pathology have been the most frequent applications of regenerative medicine injections. Platelet-rich plasma (PRP) and stem-cell injections are the most commonly used regenerative medicine injections. One major advantage of regenerative injections over other types of injections, such as corticosteroids, is the lack of negative side effects and high safety profile. Regenerative medicine injections may cause a short-term pain response but offer long-term safety, unlike corticosteroids, which may cause negative side effects with long-term applications. Therefore, given the promising clinical applications and the low risk profile, regenerative medicine injectables have increased in popularity and use over the years.

PRP injections involve a blood draw and concentrating the platelets via centrifuge. These concentrated platelets are then injected into the site of injury. The premise is that these cells will release growth factors, cytokines, and other elements to promote healing in chronic and acute injuries.

The most common categories of PRP preparations include leukocyte-rich, leukocyte-poor, and platelet-rich fibrin. The variation in types of preparations have hindered collation of data and systemic studies on PRP. In practice, many physicians choose to inject joints with leukocyte-poor PRP and tendons with leukocyte-rich PRP, but there are no data that show significant differences in clinical outcomes between the preparations.

Stem cells are another main category of regenerative medicine injection. Stem cells may be obtained from many areas of the body, including blood, adipose tissue, and bone marrow. Most current research and clinical practice have focused on adipose tissue and bone marrow aspirate concentrate because these areas yield the highest volume of stem cells. The concept of injecting stem cells is to promote growth, including angiogenesis, and recovery in an area of injury. 

Applications in Tendinopathies

For tendon pathologies, PRP and/or stem cells can be considered for both chronic and acute injuries. There continues to be limited data regarding superiority of PRP or stem cells over one another. Furthermore, in clinical practice, stem-cell injections often include PRP within the protocols. Data have shown the most significant improvement in rotator cuff tendinitis and lateral epicondylitis, with PRP injections getting the majority of this scientific support. There are less data about stem-cell injections overall, and specifically in tendon pathology. A postinjection therapy regimen for tendons is often implemented in clinical practice, but there continues to be debate over the best rehabilitation protocol. A post–tendon-injection physical therapy protocol commonly involves gradual tendon loading, with the goal of progressive restoration of tendon structure and function.

Uses in Arthritis

In degenerative joint arthritis, multiple forms of injections and regenerative medicine have shown efficacy to reduce pain and improve function. However, one type of regenerative medicine injection has not been shown to be far superior to another. Both PRP and stem-cell injections have shown promise for treatment of arthritis, but there is still much "bang for your buck" debate about how much improvement these injections are offering patients for the out-of-pocket expense.

It has been shown that earlier injections for arthritis are associated with better outcomes. Therefore, in clinical practice, many providers educate their patients that, although there are no guarantees of success, mild and moderate arthritis may have improvement in pain and function with regenerative medicine injections. For severe arthritis, the risk for complications is very low, but the efficacy of the injection is also likely to be lower.

Widely Variable Protocols

Protocols around regenerative medicine are widely variable. Some providers recommend avoiding nonsteroidal anti-inflammatory drugs and/or aspirin before and after regenerative medicine procedures. However, there are conflicting data on whether limiting these medications makes a clinically significant difference in patient outcomes.

Additionally, there are conflicting recommendations regarding ice or heat after injection. Ice may help with pain control, and heat may help to drive more blood into the area of treatment. Again, there have not been definitive studies to recommend for or against either protocol.

Lastly, there are other treatments that may drive blood flow and healing factors to an area of injury, such as blood flow restriction, extracorporeal shockwave therapy, dry needling, tendon scraping, and others. There have not been large-scale studies to demonstrate that adding these treatments to regenerative medicine procedures improve outcomes, but they have been used as adjuvants in clinical practice and may be considered.

What to Avoid

Patient and practitioners may ask what to avoid when seeking consultation for regenerative medicine procedures. In general, it is best to be cautious of practices that overpromise results. Medical science has still not been able to identify a "cure" for arthritis. Additionally, although tendon tears may demonstrate improvement in pain and function with regenerative medicine injections, a normal tendon appearance on MRI after injection is rarely visualized.

Cost is another factor to consider, and a patient may have similar beneficial outcomes with high-quality physical therapy and/or other treatments covered by their insurance. As mentioned above, therapeutic protocols around regenerative medicine, including supplements and other out-of-pocket adjuvants, have not been shown to improve efficacy significantly. Therefore, questions should be asked if a provider is recommending expensive supplements in addition to the out-of-pocket cost of an injection.

Similarly, there has been no improvement in outcomes shown with a series of injections vs a single injection, although a series of injections may be considered on an individual patient basis. A default series of regenerative medicine injections should be questioned in terms of improved outcomes for the increased cost.

Conclusions

In summary, regenerative medicine can offer patients a safe treatment option for joint and tendon pathology. However, these injections often come with an out-of-pocket expense and results are not guaranteed. There is ample room for research and development, and more research is needed to provide best recommendations for efficacy. Some areas of promising research include the manipulation of stem cells to activate desired factors and increase the concentration of certain cell properties in the injection. As regenerative medicine progresses, it is expected that more specificity in preparations, types, locations, and postinjection protocols will be optimized.

Dr Davenport is Director of Physiatry in the Department of Physiatry at the Hospital for Special Surgery Florida in West Palm Beach, Florida.

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