PRP Injections: Do They Work? What the Research Says
If you have persistent tendon pain, knee osteoarthritis, or an injury that hasn't responded to treatment, you may have come across PRP injections.
PRP, or platelet-rich plasma, is increasingly discussed as a treatment option for musculoskeletal conditions. It is often promoted as a way to stimulate healing, reduce pain, and help the body repair damaged tissue.
But how effective is it?
The answer is more complicated than you might expect.
PRP injections may help with some musculoskeletal conditions, but the evidence is mixed, and results vary depending on the condition being treated. A treatment that shows promise for one problem may not provide the same benefits for another.
Understanding what PRP is, what the research actually tells us, and where rehabilitation fits into the picture can help you make a more informed decision about your treatment options.
What Is PRP?
PRP stands for platelet-rich plasma.
It is produced using a sample of your own blood, which is processed in a centrifuge to separate and concentrate platelets within the plasma.
Platelets are best known for their role in blood clotting. They also release signalling molecules, including growth factors, that participate in the body's normal repair processes.
The aim of PRP treatment is to deliver a concentrated preparation of platelets to a targeted area, with the intention of influencing the local biological response.
Depending on the condition being treated, a clinician may inject PRP around or into a tendon, into a joint, or into another affected area.
PRP is an autologous treatment, meaning it is derived from your own blood.
However, using your own blood does not automatically mean a treatment is effective, risk-free, or appropriate for every condition.
PRP preparations also vary. The concentration of platelets, the presence of white blood cells, the preparation method, and the injection protocol can differ between providers and studies.
These differences make it difficult to treat PRP as one standardised intervention or assume that the results of one study apply to every PRP product.
What Does the Research Say About PRP Injections?
One of the most important things to understand about PRP is that its effectiveness depends on the condition being treated.
Let's look at some of the areas where PRP has received the most attention.
1. PRP for Knee Osteoarthritis
Knee osteoarthritis is one of the most frequently discussed applications of PRP.
Osteoarthritis involves changes to the whole joint, including the cartilage, underlying bone, joint lining, and surrounding tissues. It can cause pain, stiffness, and reduced function.
Some clinical trials and systematic reviews have reported improvements in pain and function following PRP injections in people with knee osteoarthritis.
However, not all high-quality studies have found a meaningful benefit.
A particularly important study is the RESTORE randomised clinical trial, published in JAMA in 2021.
Researchers compared PRP injections with saline injections in people with symptomatic knee osteoarthritis. At 12 months, PRP did not produce a significant improvement in knee pain compared with saline. The study also found no significant difference in the loss of cartilage volume between the groups.[1]
This is an important finding because PRP is sometimes promoted as a way to regenerate cartilage or slow the progression of osteoarthritis.
The evidence does not currently justify promising that PRP will regrow cartilage or reverse osteoarthritis.
Other studies and meta-analyses have reported more favourable results, including improvements in pain and function. Differences in PRP preparation, patient selection, treatment protocols, and study design may contribute to the inconsistent findings.
What does this mean if you have knee osteoarthritis?
PRP may be an option worth discussing with an appropriate medical professional, but it should not be presented as a guaranteed solution or a proven way to regenerate cartilage.
Exercise-based rehabilitation remains an important part of managing knee osteoarthritis. Improving strength, maintaining physical activity, and developing the capacity to perform the activities that matter to you can all contribute to better function.
If PRP is being considered, it is worth discussing the uncertainty around its benefits, the cost, the potential risks, and how it would fit into your broader management plan.
2. PRP for Tendon Injuries
Tendon pain is another area where PRP injections are frequently promoted.
Common examples include:
Achilles tendinopathy
Patellar tendinopathy, often called jumper's knee
Tennis elbow
Some rotator cuff conditions affecting the shoulder
Tendons adapt to the forces placed upon them. When the demands placed on a tendon exceed its current capacity, pain and reduced function can develop.
PRP has attracted interest because platelets release signalling molecules involved in tissue repair. The hope is that injecting PRP into or around an affected tendon may help improve the tendon’s response to the problem.
However, biological plausibility does not necessarily translate into better clinical outcomes.
A particularly relevant example is a randomised clinical trial published in JAMA in 2021 examining PRP injections for chronic midportion Achilles tendinopathy.[2]
The researchers compared a PRP injection with a sham injection. At six months, PRP did not provide a significant improvement in Achilles tendon function compared with the sham treatment.
This matters because Achilles tendinopathy is one of the conditions for which PRP is commonly discussed.
The findings do not prove that PRP can never help any tendon condition. Different tendons, presentations, PRP preparations, and treatment protocols may produce different results.
However, they do show why it is important not to assume that PRP is effective simply because it is marketed as a regenerative treatment.
What about tennis elbow, patellar tendinopathy, and shoulder pain?
Research into these conditions has produced varied findings.
Some studies report improvements following PRP injections, while others find limited or inconsistent benefits. The quality of the evidence and the duration of follow-up also vary.
It is therefore difficult to make a blanket statement that PRP works for tendon injuries as a whole.
The more useful question is whether there is convincing evidence that PRP improves outcomes for your specific condition, compared with appropriate alternative treatments.
3. PRP for Muscle Injuries and Other Sports Injuries
PRP has also been investigated for acute muscle injuries and other sports-related problems.
The theory is that platelet-derived signalling molecules may influence aspects of the repair process.
However, research in this area has not established a consistent benefit across sports injuries, and results from one type of injury cannot automatically be applied to another.
For athletes, a key consideration is whether PRP improves meaningful outcomes such as:
Time to return to sport
Recovery of strength and function
Risk of reinjury
Ability to tolerate training and competition
A treatment that changes a biological marker does not necessarily lead to a faster or more complete return to sport.
Athletes should be cautious about claims that PRP will reliably accelerate recovery or get them back to competition sooner.
Treatment decisions should be based on the nature of the injury, the available evidence, the athlete's circumstances, and a structured rehabilitation plan.
Why Is the Evidence for PRP So Mixed?
There are several reasons why studies of PRP can reach different conclusions.
1. PRP is not one standardised product.
Different preparation systems produce different platelet concentrations and cellular compositions. Protocols can also differ in how the PRP is activated, administered, and repeated.
2. Different conditions have different biological and mechanical demands.
Knee osteoarthritis, Achilles tendinopathy, tennis elbow, and acute muscle injuries are not the same problem.
They involve different tissues, mechanisms, and recovery processes. A positive result in one condition does not establish effectiveness in another.
3. Studies measure different outcomes.
Some studies focus on pain. Others measure function, imaging changes, return to sport, or quality of life.
These outcomes are not interchangeable. For example, an improvement in pain does not necessarily demonstrate that damaged tissue has regenerated.
4. Study quality and comparison treatments matter.
The results of a small study without a suitable control group may be less reliable than those of a well-designed randomised clinical trial.
It is also important to know what PRP is being compared with. A treatment may appear beneficial when compared with no treatment but offer little additional benefit when compared with a placebo or an effective rehabilitation programme.
These differences are part of the reason why systematic reviews and clinical guidelines may reach different conclusions.
Does PRP Replace Physiotherapy?
No. PRP injections and physiotherapy serve different purposes.
An injection may be considered as one component of treatment for a particular condition. Physiotherapy focuses on helping you improve movement, strength, function, and your ability to tolerate the demands of everyday life or sport.
For many tendon conditions, progressive loading is a central part of rehabilitation.
This involves gradually exposing the affected tendon to appropriate levels of force, allowing its capacity to develop over time.
For someone with Achilles tendinopathy, for example, rehabilitation may involve progressive calf strengthening, followed by more demanding activities such as running and jumping when appropriate.
For someone with knee osteoarthritis, treatment may focus on improving lower-limb strength, physical capacity, and confidence with activities such as walking, stairs, and exercise.
The programme needs to reflect the individual, their symptoms, their goals, and their current capacity.
If an injection is used, the rehabilitation plan should still be tailored to the condition and the treating clinician's advice.
It is also important to recognise that an injection does not automatically correct the factors contributing to a problem. Training load, strength, movement demands, recovery, and the ability to tolerate activity may still need to be addressed.
The goal is not simply to reduce pain. It is to improve your ability to do the things that matter to you.
Is PRP Safe?
Because PRP is prepared from your own blood, it is often described as a relatively natural treatment.
However, this does not mean it is completely risk-free.
Potential risks include:
Temporary pain or soreness following the injection
Bleeding or bruising
Infection
Irritation or a temporary increase in symptoms
The risks depend partly on the injection site, the procedure, and the individual's circumstances.
PRP may also be unsuitable in some situations, depending on medical history, medications, blood-related conditions, and other factors. A qualified medical professional should assess whether it is appropriate.
Another consideration is cost. PRP treatment can be expensive, and the degree of benefit is uncertain for many conditions. It is worth understanding the likely costs and realistic expectations before proceeding.
Should You Consider PRP?
There is no universal answer.
PRP may be worth discussing with your treating doctor for certain conditions, but it should not be viewed as a guaranteed solution or a replacement for appropriate rehabilitation.
Before proceeding, consider asking:
What evidence supports PRP for my specific condition?
What improvement can I realistically expect?
How does it compare with other treatment options?
What are the risks and costs?
What will my rehabilitation involve afterwards?
How will we measure whether the treatment has worked?
These questions help shift the conversation away from marketing claims and towards an informed treatment decision.
PRP Injections and Physiotherapy in Tokyo
If you are experiencing persistent tendon pain, knee pain, or a sports injury, it can be difficult to know which treatment is right for you.
At Club 360, our physiotherapists assess the nature of your symptoms, your physical capacity, and the demands you want to return to.
We can help identify appropriate rehabilitation strategies, guide your return to activity, and work alongside other healthcare professionals when additional medical assessment or treatment is needed.
If you are considering PRP injections in Tokyo, it is worth understanding both the potential benefits and the limitations of the evidence before making a decision.
PRP may have a role in some situations, but the right treatment starts with understanding the problem.
If you have persistent pain or an injury that is affecting your training, sport, or everyday life, contact Club 360 to arrange a physiotherapy assessment.
References
Bennell KL, Paterson KL, Metcalf BR, et al. Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial. JAMA. 2021;326(20):2021–2030. doi:10.1001/jama.2021.19415.
Kearney RS, Ji C, Warwick J, et al. Effect of Platelet-Rich Plasma Injection vs Sham Injection on Tendon Dysfunction in Patients With Chronic Midportion Achilles Tendinopathy: A Randomized Clinical Trial. JAMA. 2021;326(2):137–144. doi:10.1001/jama.2021.6986.
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