PRP Therapy for the Knee Joint -

Principle of the Method

The PRP method for treating knee joints is based on enhancing the regeneration of intra-articular tissues. Thanks to platelet-rich plasma, the recovery of cartilage, menisci, ligaments, and other tissues is accelerated.

Even in ancient times, doctors noticed that traumatic injuries accompanied by hematoma formation healed significantly faster. The reasons for this have been established only in recent decades. It was found that platelets release a number of substances that accelerate regeneration. These growth factors include:

  • Epidermal
  • Epithelial
  • Endothelial
  • Fibroblast
  • Insulin-like
  • Transforming

These substances have a polypeptide (protein) structure and serve various functions. However, all the listed compounds participate in tissue regeneration. They stimulate the mitotic activity of cells, accelerating their growth and division.

PRP therapy for the knee joint significantly enhances the reparative processes of both soft and bone tissues. Platelet-rich plasma is increasingly used in medicine for various injuries, including soft tissue damage, muscle and ligament tears, and bone fractures. All types of tissues regenerate faster in the presence of a sufficient number of platelets.


Among knee joint diseases, the indications for using PRP include the following conditions:

  • Arthrosis of the knee joint or gonarthrosis: This degenerative-dystrophic disease involves the gradual degradation of joint cartilage. Applying PRP at stages 1-2 improves regenerative processes in the cartilage tissue, significantly slowing down the pathological process. PRP can alleviate many symptoms of arthrosis, delay the need for knee replacement surgery, or even avoid surgery entirely when used as part of an effective conservative therapy scheme.
  • Injuries: The knee is often injured by athletes, commonly resulting in ligament tears, meniscus damage, and intra-articular fractures. If the doctor concludes that conservative treatment is sufficient, PRP can be used to accelerate the healing of injuries, which otherwise might take weeks or even months to heal.
  • Surgeries: After arthroscopic surgical interventions on the knee, a rehabilitation period is necessary until all tissue damage is repaired. PRP can be used to speed up this process.
  • Joint surface defects: PRP is used for cartilage deficiencies on joint surfaces of any origin. Causes can include injuries, arthrosis, inflammatory knee diseases, metabolic disorders, psoriasis, systemic connective tissue diseases, and other conditions. PRP can enhance regenerative processes for minor defects. For significant cartilage thinning, surgical treatment is indicated.


Blood is drawn from the patient's cubital vein. The patient then waits for about 20 minutes for the intra-articular injection to be prepared. During this time, the preparation undergoes centrifugation, which can be either single or double-step. The single-step process better preserves platelet integrity, while the double-step process results in a higher concentration of platelets.

After preparing the PRP, the plasma from the PRP tubes is injected intra-articularly. The injection site is anesthetized, so the patient does not experience significant pain during the procedure, which is comparable in discomfort to an intramuscular injection—unpleasant but tolerable.

Some patients feel a sense of fullness inside the joint, especially when a large volume of plasma is injected. After the injection, the doctor asks the patient to perform flexion and extension movements in the knee joint to help distribute the plasma within the joint cavity. After 10 minutes, the patient can go home. Hospitalization and additional monitoring are not required.

PRP can be administered in courses of varying durations. Typically, PRP is injected once a week, with a total of 3 to 7 injections. The treatment regimen is tailored individually by the doctor, based on the clinical situation and the goals of using platelet-rich plasma.

Effectiveness in Osteoarthritis

The timing of results depends on the goals of PRP application and the indications for treatment. In any case, the effect is not immediate. PRP is not a pain reliever. Platelet-rich plasma merely enhances tissue regeneration, and this process takes quite a lot of time.

In knee osteoarthritis, the maximum effect develops 3-6 months after the start of treatment. Only a few patients notice a reduction in pain syndrome after the first injection. For the rest, the first results are achieved within a month of starting therapy.

Comparative studies show that PRP achieves much better results than intra-articular glucocorticoid injections. These differences are especially noticeable in stage 3 gonarthrosis. Patients experience less pain with this treatment method. Moreover, PRP has a more favorable effect on cartilage - plasma stimulates its regeneration, whereas glucocorticoids have a chondrotoxic effect.

According to E. Kon, 80% of people were satisfied with the results of PRP treatment for osteochondrosis after a series of injections. Results were evaluated after 5 weeks. Another study showed that 67.3% of patients rated the results of PRP therapy for knee osteoarthritis as positive six months after treatment, compared to only 4.3% in the control group.

In another study, the average time from the first injection to the therapeutic result was calculated. Patients considered this to be the reduction of clinical symptoms. This period was 17.63 days.

It should be noted that PRP has two main effects: anti-inflammatory and reparative. Patient surveys typically account for only the short-term symptomatic effect. This effect develops more quickly after platelet-rich plasma injections but also diminishes more rapidly after the treatment course is completed. The initial results of treatment are due to hyperplasia of the synovial membrane and modulation of cytokine levels in the joint cavity.

The primary effect of PRP, however, is chondrogenesis. This process occurs very slowly, and patients cannot feel it. Only by comparing symptoms and radiological indicators of the primary and control groups can researchers obtain data on the effectiveness of PRP therapy for the knee joint several months after the treatment course.

Post-Operative Use

PRP therapy for the knee is used after surgical operations on ligaments and menisci. Numerous studies demonstrate the effectiveness of this procedure in accelerating the recovery of intra-articular structures.

One of the frequent applications is for anterior cruciate ligament (ACL) tears. The ACL cannot fully recover from a complete tear on its own. Therefore, surgical treatment is used for its normalization (ligamentization). Free autografts are used for this purpose.

There are different types of autografts. STG (semitendinosus and gracilis tendons) and BTB (bone-patellar tendon-bone) grafts are used. In both cases, PRP injections into the knee allow for significant positive treatment results.

Primarily, PRP is used to accelerate the rehabilitation period. Studies show that with STG grafts, the ligamentization period averages 369 days (about 1 year), while PRP reduces this period to 177 days (6 months). Thus, the time is halved.

Even more significant results are achieved with PRP therapy for the knee after using BTB grafts for ACL reconstruction. The average ligamentization period is about 1 year. With PRP, this period is reduced to 3.5 months.

Studies show that ligamentization after surgery is significantly better in patients receiving PRP therapy compared to the control group. However, the results are better only 4-6 months after surgery. One-year follow-up shows that the final results are the same.

Nevertheless, PRP therapy significantly reduces recovery time for patients after surgery. This is particularly important for professional athletes who want to return to training as soon as possible.


PRP therapy for the knee joint is one of the safest treatment methods. There is no risk of complications, except for the human factor. A doctor may miss the joint with the needle or introduce an infection if asepsis and antisepsis rules are not followed.

However, if you consult a highly qualified specialist with extensive experience in such medical procedures, the process will go smoothly. In cases of joint deformation where it is difficult for the doctor to reach the joint cavity, ultrasound can be used. Therefore, there is no risk of damaging healthy tissues during PRP therapy.

The PRP preparation for injection into the joint cavity is made from the patient's blood. Thus, there is no risk of infection transmission or allergic reactions. The patient's own blood carries no antigenic load and is completely safe.

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