Orthobiologics in Sports Medicine

What Are Orthobiologics?

Orthobiologics are biologic products used with the goal of influencing the local environment around an injured or arthritic joint, tendon, muscle, or bone. Depending on the treatment, the material may come from the patient’s own blood, bone marrow, or adipose tissue, or from another biologic source.

The term “regenerative medicine” is often used in advertising, but it can imply more than the science currently supports. A treatment may reduce pain or influence inflammation without actually regenerating normal cartilage, tendon, or other tissue. For that reason, we prefer to describe the specific product being considered and the evidence for the specific condition being treated.

Platelet-Rich Plasma (PRP)

PRP is prepared from a patient’s own blood. The blood is processed to concentrate platelets within a smaller volume of plasma. Platelets contain signaling proteins and growth factors involved in inflammation, tissue repair, and healing. PRP is not a stem-cell treatment.

There is no single universal PRP product. Preparations differ in platelet concentration, total platelet dose, leukocyte content, activation, processing technique, injection volume, and number of injections. These differences are important because they may partly explain why clinical studies sometimes reach different conclusions.

  • Knee osteoarthritis is one of the best-studied orthopedic applications of PRP. Multiple randomized trials and meta-analyses suggest that PRP can improve pain and function in appropriately selected patients, particularly over the first 6 to 12 months. Recent analyses have reported clinically meaningful benefit compared with placebo or hyaluronic acid in many study populations.

    The evidence is not uniformly positive. Some rigorous placebo-controlled trials have found little or no difference between PRP and saline, and the PRP literature remains heterogeneous. The most defensible conclusion is that PRP is a reasonable symptom-modifying option for selected patients—not a guaranteed treatment and not a cure for arthritis.

  • PRP has been studied for chronic tendinopathies, but the evidence varies substantially by tendon. It should not be assumed that a positive study for one tendon applies to every tendon problem.

    Lateral epicondylitis (tennis elbow): among the more supportive tendon indications. Recent meta-analyses suggest that appropriately prepared PRP may provide longer-term symptom improvement in selected patients, although study protocols remain variable.

    Achilles tendinopathy: high-quality placebo-controlled evidence has not demonstrated a meaningful benefit for routine PRP injection in chronic midportion Achilles tendinopathy.

    Rotator cuff tendinopathy and partial tears: current AAOS guidance does not support routine PRP injection for these conditions. PRP used during rotator cuff surgery is a separate question and has different evidence.

    Patellar, gluteal, and other tendinopathies: some studies are encouraging, but the evidence is less consistent and treatment should remain diagnosis-specific.

    For chronic tendinopathy, progressive tendon loading and rehabilitation remain central. PRP, when considered, should generally be viewed as an adjunct rather than a substitute for an appropriate rehabilitation program.

  • PRP has also been studied for acute muscle injuries, especially hamstring strains. Although the biologic rationale is attractive, clinical studies have produced mixed results for return-to-sport timing and reinjury. At present, PRP should not be presented as a proven way to accelerate routine muscle healing; structured rehabilitation remains the foundation of treatment. Platelet poor plasma (PPP), however, has demonstrated promising but early evidence to support its use in acute muscle injuries with a moderately strong biologic rationale for its use.

Safety and Practical Considerations With PRP

Because PRP is autologous, allergic or immune reactions to the injected material are uncommon. Temporary pain, swelling, stiffness, or soreness after injection can occur, and—as with any injection—bleeding and infection are possible. Clinical trials suggest most reported adverse events are mild and self-limited, but PRP is not risk-free.

Insurance coverage is variable, and PRP is frequently an out-of-pocket treatment. Patients should understand the expected benefit, alternatives, cost, and the specific PRP preparation being used before proceeding.

“Stem Cells” and Cell-Based Orthobiologics

The phrase “stem-cell injection” is frequently used as if it describes one standardized treatment. It does not. Products marketed under this label may include bone marrow aspirate concentrate (BMAC), adipose-derived preparations, stromal vascular fraction, culture-expanded mesenchymal stromal/stem cells, umbilical-cord or Wharton’s-jelly products, amniotic products, or exosomes. These products are biologically and regulatorily different and should not be considered interchangeable.

  • BMAC is obtained by aspirating bone marrow—commonly from the pelvis—and concentrating portions of the aspirate. It contains platelets, cytokines, hematopoietic cells, and a relatively small population of mesenchymal stromal cells. Calling BMAC simply a “stem-cell injection” can therefore be misleading.

    Studies of BMAC for knee osteoarthritis have reported improvements in pain and patient-reported outcomes, but comparative studies have not consistently shown that BMAC is superior to PRP, other orthobiologics, or placebo. The evidence base is substantially smaller than the PRP literature.

  • Adipose tissue contains stromal and vascular cells that have generated substantial research interest. Products include microfragmented adipose tissue and stromal vascular fraction, as well as culture-expanded adipose-derived mesenchymal stromal cells in research settings. Some trials show improvements in pain and function in knee osteoarthritis, but comparative evidence does not consistently demonstrate superiority over PRP or other established injection strategies.

  • Culture-expanded mesenchymal stromal/stem cells are fundamentally different from point-of-care BMAC or microfragmented adipose tissue. Some controlled clinical trials have shown improvements in knee pain and function. However, evidence for durable structural cartilage restoration remains uncertain, and long-term disease-modifying benefit has not been established.

  • These products are heavily marketed directly to patients. FDA has specifically stated that regenerative medicine products such as stem-cell products, stromal vascular fraction, umbilical-cord/Wharton’s-jelly products, amniotic products, and exosomes have not been approved for orthopedic conditions such as osteoarthritis, tendinitis, or joint pain. FDA also states that there are currently no FDA-approved exosome products for treatment of disease.

Can Cell-Based Treatments Regrow Cartilage?

This is one of the most important areas where marketing can exceed evidence. Some cell-based studies report symptomatic improvement, and selected studies have reported imaging or biomarker changes. However, large comparative trials have not established reliable restoration of normal articular cartilage or reversal of established osteoarthritis. Patients should be cautious of claims that an injection will “regrow a new knee” or predictably eliminate the future need for surgery.

Important regulatory distinction:
A product being described as “registered,” “listed,” “from a tissue bank,” or appearing on ClinicalTrials.gov does not mean that FDA has approved it for treatment of an orthopedic condition. Patients should ask exactly what product is being administered and what its regulatory status is.

How We Evaluate an Orthobiologic Treatment:

  • What exactly is the product, and where does it come from?

  • Is there high-quality human evidence for this specific diagnosis—not simply animal or laboratory evidence?

  • What outcome has actually been demonstrated: pain relief, improved function, faster healing, structural regeneration, or something else?

  • How standardized is the preparation, and is the dose/composition known?

  • What are the known risks and the important unknowns?

  • Is the product FDA-approved for the proposed use, or is it investigational?

  • How does it compare with rehabilitation, medications, established injections, or surgery?

Our Perspective:

Orthobiologics are an important and rapidly evolving area of sports medicine. PRP has enough human evidence to be considered for selected conditions, particularly knee osteoarthritis and certain chronic tendinopathies. Cell-based therapies are scientifically promising, but the products are heterogeneous and the evidence is less mature. We support innovation while avoiding claims of cartilage regeneration, tissue restoration, or “cure” unless those claims are demonstrated by high-quality human data.

Selected Evidence:

  1. AAOS Technology Overview Summary: Platelet-Rich Plasma for Knee Osteoarthritis. JAAOS (2024). Direct link — AAOS systematic evidence overview.

  2. PRP Injections for Knee Osteoarthritis: Clinical Significance and Platelet Concentration. American Journal of Sports Medicine (2025). Direct link — Meta analysis of placebo-controlled randomized trials.

  3. Effect of Intra-articular PRP vs Placebo on Pain and Cartilage Volume in Knee OA. JAMA (2021). Direct link — Important negative placebo-controlled trial.

  4. Platelet Concentration and PRP Outcomes for Lateral Epicondylitis. American Journal of Sports Medicine (2025). Direct link — Systematic review and meta-regression.

  5. PRP vs Sham Injection for Chronic Midportion Achilles Tendinopathy. JAMA (2021). Direct link — Large randomized placebo-controlled trial.

  6. Cell-Based vs. Corticosteroid Injections for Knee Osteoarthritis. Nature Medicine (2023). Direct link — Multicenter randomized phase 2/3 trial.

  7. AAOS Technology Overview Summary: Concentrated Bone Marrow Aspirate for Knee Osteoarthritis. JAAOS (2023). Direct link — Systematic overview of BMAC evidence.

  8. FDA Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. U.S. Food and Drug Administration (current FDA resource). Direct link — Regulatory and patient-safety information.

  9. FDA: Important Patient and Consumer Information About Regenerative Medicine Therapies. U.S. Food and Drug Administration (current FDA resource. Direct link — Risks and approval status of marketed regenerative products.