PRP vs. Cortisone Injections: An Evidence-Based Comparison

Cortisone injections have anchored musculoskeletal pain management for decades. Platelet-rich plasma therapy is a fundamentally different approach. Both are injectables delivered to the same kinds of joints and tendons. But they work through opposite biological mechanisms and produce very different outcomes over time.

This is not an argument against cortisone. It is an honest comparison of what each treatment does, what the evidence shows, and when each one is the right clinical choice. I perform both in my practice, and I recommend based on what the patient's tissue actually needs.

How Cortisone Works

Corticosteroid injections deliver a potent synthetic anti-inflammatory right to the site of pain. The mechanism is simple. Cortisone suppresses the inflammatory cascade. It inhibits prostaglandin and leukotriene synthesis, reduces vascular permeability, and blocks immune cell migration to the affected tissue. The result is rapid pain relief, often within 24 to 72 hours, and a meaningful drop in swelling.

For patients in acute pain, that is genuinely valuable. A cortisone injection into an inflamed bursa, an acutely swollen knee, or a flared tendon sheath can restore function fast and let the patient start rehabilitation. It can also serve a diagnostic purpose. If injecting a specific structure eliminates the pain, you have confirmed the pain generator, which guides further treatment.

What cortisone does not do is repair tissue. It does not stimulate collagen synthesis, recruit reparative cells, or reverse degeneration. It suppresses the inflammatory response, which in acute situations is the problem. But in chronic degenerative conditions, the problem is not too much inflammation. The problem is tissue that has failed to heal. Suppressing inflammation there treats the symptom while leaving the underlying pathology unchanged.

How PRP Works

Platelet-rich plasma comes from the patient's own blood. We draw a venous sample, centrifuge it to concentrate the platelet fraction, and inject it into the target tissue under ultrasound guidance. The concentrated platelets release a cascade of growth factors: platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1), and others. These signal the tissue to start active repair.

This is a fundamentally different proposition than cortisone. PRP does not suppress inflammation. It deliberately starts a controlled inflammatory response, the kind the body uses to heal an acute injury. It recruits stem cells and progenitor cells to the site, stimulates collagen synthesis, promotes new blood vessel formation, and shifts the tissue environment from chronic degeneration toward active regeneration.

The trade-off is time. PRP does not provide rapid pain relief. Most patients feel increased soreness for the first one to two weeks as the healing cascade activates. Meaningful improvement usually emerges at four to six weeks and keeps developing over three to six months. For a patient who needs immediate relief from an acute flare, PRP is the wrong tool. For a patient with a chronic tendon or joint problem that has failed to heal on its own, it may be exactly right.

Head-to-Head: What the Evidence Shows

The most instructive study here remains the work by Gosens and colleagues, published in the American Journal of Sports Medicine. It examined PRP versus cortisone for lateral epicondylitis, or tennis elbow. It is an ideal comparison case. Lateral epicondylitis is one of the most common chronic tendinopathies, it is frequently treated with cortisone, and the tissue pathology is well characterized.

At four weeks, the cortisone group was doing better. Pain scores improved faster, which is exactly what you expect from a potent anti-inflammatory. At eight weeks, the two groups were roughly equal. But at one year, the PRP group had significantly better outcomes. The cortisone patients had regressed, many back to baseline or worse, while the PRP patients kept improving.

This pattern, cortisone winning short-term and PRP winning long-term, has been replicated across multiple conditions. Meta-analyses of chronic tendinopathy have found PRP outperforming cortisone at follow-up beyond three months. For knee osteoarthritis, systematic reviews have shown PRP giving more durable pain relief and functional improvement than corticosteroid injection at six and twelve months. The post on PRP for knee osteoarthritis covers those findings in more detail. For heel pain specifically, our post on PRP for plantar fasciitis compares the same two options.

The reason for this divergence is not mysterious. Cortisone provides temporary symptom suppression without tissue repair. When the anti-inflammatory effect wears off, the underlying pathology remains. PRP stimulates actual structural change in the tissue. The improvement takes longer to show, but it reflects genuine biological repair rather than pharmacological masking.

When Cortisone Is the Right Choice

None of this means cortisone is a bad treatment. It means cortisone is a specific tool with specific appropriate uses. I still give cortisone injections in my practice when the clinical situation calls for them.

Acute inflammatory flares. A patient with an acutely inflamed bursa, a crystal arthropathy flare (gout, pseudogout), or an acute tendon sheath inflammation needs the inflammation controlled now, not in six weeks. Cortisone is the right tool.

Diagnostic injection. When the pain generator is uncertain, injecting cortisone into a specific joint or structure under fluoroscopic or ultrasound guidance can confirm the diagnosis. If the pain resolves, you have identified the source. That information is valuable regardless of the long-term plan.

Bridging to rehabilitation. Some patients are in too much pain to take part in physical therapy. A cortisone injection that reduces pain for four to six weeks can open a window for the exercise-based treatment that will address the underlying dysfunction. Here cortisone is not the treatment. It is the gateway to treatment.

Patients who cannot wait. An athlete with a competition in two weeks. A patient with a critical work deadline. Someone who needs functional improvement now for legitimate reasons. PRP's slower onset makes it impractical in these situations.

When PRP Is the Better Option

PRP is the stronger choice when the picture involves chronic degeneration rather than acute inflammation, and when the goal is durable tissue improvement rather than temporary symptom relief.

Chronic tendinopathy. Tennis elbow, Achilles tendinopathy, patellar tendinopathy, and rotator cuff tendinopathy. These are conditions where the tendon has undergone degenerative change (technically tendinosis, not tendinitis) and the tissue needs repair, not anti-inflammatory suppression.

Mild to moderate osteoarthritis. Cartilage degeneration in the knee, hip, or other joints, where the goal is to slow progression and improve the biological environment within the joint. PRP's growth factors can modulate the intra-articular environment and support chondrocyte function in ways cortisone cannot.

Partial ligament or muscle tears. Incomplete tears where surgery is not indicated but the tissue needs biological support to heal well.

Failed cortisone. This may be the clearest indication. A patient who has had two or three cortisone injections for the same problem with diminishing returns. That pattern of decreasing benefit is itself evidence that the problem is not primarily inflammatory, and that a regenerative approach may fit better.

The Risks of Repeated Cortisone Injections

This is where the comparison matters most. A single cortisone injection for an appropriate indication carries minimal risk. But too often the pattern in practice is serial cortisone injection: three, four, five or more shots into the same joint or tendon over months or years, because the relief wears off and the patient returns for another.

Repeated corticosteroid exposure has well-documented adverse effects on tissue:

• Tendon weakening and rupture. Cortisone inhibits tenocyte proliferation and collagen synthesis. Multiple injections into or near a tendon can progressively weaken its structure. Achilles tendon rupture after repeated cortisone injection has been reported in the literature.
• Cartilage thinning. Intra-articular corticosteroids accelerate cartilage breakdown with repeated use. A 2017 randomized trial published in JAMA found that patients receiving triamcinolone injections every three months for two years had significantly greater cartilage volume loss than those given saline placebo, with no significant difference in pain outcomes.
• Local tissue atrophy. Subcutaneous fat atrophy and skin depigmentation at the injection site, especially with superficial injections.
• Systemic effects. Transient blood glucose elevation (significant for diabetic patients), adrenal suppression with frequent injections, and possible effects on bone density with cumulative exposure.

Most physicians follow a guideline of no more than three to four cortisone injections per joint per year, and some experts recommend no more than three lifetime injections per tendon. When a patient reaches that threshold without lasting improvement, continuing with cortisone is not just ineffective. It can harm the very tissue you are trying to treat.

How Dr. Knopp Approaches the Decision

Every patient who comes to this practice for joint or tendon pain gets a thorough evaluation before we discuss any injection. The choice between PRP and cortisone is not ideological. It is clinical, based on what the tissue needs and what the patient's goals are.

The evaluation includes a detailed history of prior treatments (including how many cortisone injections the patient has already had), a complete musculoskeletal and osteopathic structural exam, and imaging review when indicated. From that assessment, the recommendation follows the tissue, not a protocol.

For some patients, a single cortisone injection is the right first step: to reduce acute inflammation, confirm a diagnosis, or open a rehabilitation window. For others, especially those with chronic degenerative conditions or a history of diminishing returns from cortisone, PRP offers a different biological approach. It addresses the underlying tissue pathology rather than temporarily masking the symptoms.

The patients I see most often for this conversation fall into two groups. Active adults over fifty with knee or shoulder pain managed with periodic cortisone for a year or more. And younger athletes with chronic tendon problems that have not responded to rest and physical therapy alone. Both groups tend to be excellent PRP candidates, and both deserve an honest discussion about what each treatment can and cannot do.