PRP Applications in Knee Problems

PRP Applications in Knee Problems

28 March 2019 11:26

PRP (Platelet Rich Plasma) Applications in Knee Joint Problems Rudiments

Platelet is one of the three cell types found in the blood. Its main task is to create a plug (clot) to ensure that blood flow stops when injury occurs. In order to achieve this, platelet cells contain densely growth factors and cytokines which can be called restorative proteins. The preparate obtained by increasing the concentration of platelet (platelets) through taking the patient's own blood and subjecting it to mechanical application is called as PRP. With this concentration, which is well above the physiological limits, growth factor and proteins called cytokines are densely applied to the region. It is already known that these proteins are invoking the restorative cells into the injured area (alarm task). With this application, it is assumed that first a restoration will be provided in the area where pain is caused by tissue pathology, and consequently the pain will decrease or disappear. THE EFFECT OF THE SAID MECHANISM ON TENDON INJURY (IN VITRO) WAS PROVEN IN EXPERIMENTAL STUDIES. On the other hand, the extent to which the growth factors are released after the administration in PATIENTS (IN VIVO), their exact mechanism of action and duration of these and the response of normal tissues to this application are not known exactly.

We can roughly outline the knee joint problems that PRP treatment is applied in the last 10 years, which is at least intended to eliminate pain:


1) Tendon (tendinea) injuries:

a) Anterior knee pain (patellar tendinitis)

b) Stimulation of tendon repair

2) Ligament injuries:

a) Knee joint internal lateral ligament injuries

3) Cartilage problems (wear-calcification)

a) Repair of large-area cartilage wear-loss

b) Calcification-wear in knee joint (osteoarthritis)

c) Repair of meniscus injuries

d) Strengthening knee anterior cruciate ligament repair

4) Bone problems

a) Broken healing problems (nonunion)

b) In the treatment of non-healing stress fractures in athletes

The vast majority of studies are observational and subjective. In other words, it is stated that a condition of well-being is observed but its mechanism of action cannot be revealed and it is not known how long this wellness will last.

What is Autologous PRP?

“Autologous” means one's own body. In other words, a person's own tissue is used as a source, not the texture of another person or animal. With this method, a person’s own plasma, ie growth factors, is concentratedly applied to the wounded or patient tissue.

Preparation of PRP and Classification

Currently, 16 different types of PRP preparation system are sold in the USA. Basically, some blood is taken from the patient's venous system and the red blood cells (erythrocytes) are separated by centrifugation. The obtained liquid fraction (plasma) is further reprocessed and the platelet-rich plasma (PRP) is eluted from platelet-poor plasma. Depending on the differences in the systems on sale, the platelet density ratio may be 1.6 to 14 times higher than normal blood. Furthermore, the amount of white blood cells (leukocytes) in the PRP obtained in each system also varies. Another variant factor is whether various chemical agents called activator are added into the prepared PRP. The general opinion is that it would be better if the activator was not involved. The chemicals called activators are in sum calcium and thrombin. It has sometimes been observed that during the application, these form clot early (inside the injector). It was stated that PRP, to which activators were not added, released growth factors as soon as it comes into contact with the protein called collagen, which is present in the tendon.

In summary, PRP solutions applied in patients are not uniform. For this reason, it is not possible to analyze the publications collectively. There are 3 important factors that differentiate each PRP preparation from others:

1-Platelet concentration / total amount obtained (density)

2-The amount of leukocytes

3- Whether activator is used.

How PRP Affects

PRP has been used for many years by the orthopedic surgeons in order to relieve the pain in the musculoskeletal system disorders- especially those progressing with chronic pain. Two main problems are that the mechanism of action cannot be fully revealed and it is not clear whether this effect is permanent.

Chronic anterior knee pain, patellar tendinitis (Jumpers knee): Repair in the body after tendon injury occurs in 3 periods. The period of inflammation (inflammation), the formation period and the remodeling period. The process begins with the accumulation of blood in the area after injury. This accumulation is called hematoma. The platelets in the hematoma are then activated and release the growth factors in their body. Cell flow begins in the region and the draft healing tissue that we call granuloma is formed. This tissue begins producing the protein which is called collagen, and is the main building block of the body. Then, the modeling and improving the quality of the scar (healing of scar) tissue(remodelling) begins. Although growth factors are known to have early stimulating and healing effects, whether these have long-term benefits are to be investigated.

It has been shown by animal experiments that PRP application improves the healing rate in the patellar tendon healing (tendinea in knee anterior). Moreover, in the prospective clinical studies with comparative groups, the PRP treatment group showed a better and shorter recovery time, and a high level of improvement in sports activities.

Influence on cartilage problems: It has been shown by the animal experiments that the application of PRP increases the rate of recovery of large cartilage losses and increases the quality of the healing tissue.

Knee joint calcification-wear (osteoarthritis): In patients with knee joint calcification, it was observed that 3 PRPs performed in the joint significantly alleviated pain in the knee joint and increased movement limit. However, the number of patients undergoing treatment is low and the follow-up period is short (12 months). In another study involving 120 patients, it was observed that the results of the PRP administration were statistically significantly better than the intraarticular Hyaluronic acid administration.


Areas Where PRP Applications in Musculoskeletal Disorders Are Not Effective

PRP applications related to joint calcification (osteoarthritis) were performed on average 1-3 patients. To summarize, PRP treatment should not be seen as an alternative to the surgical treatment of osteoarthritis (calcification). It should not be considered that PRP treatment may be an alternative or eliminate the need for surgery in a patient whose surgical treatment (total prosthesis) is indicated by an orthopedic specialist. New studies should be expected on this matter.

Possible Problems

The most important possible problem is the inability to receive the desired response to the treatment. In addition, the injection of the application includes a painful process at the least. Another important issue is the material result. Many health insurance institutions still accept PRP treatment at the research stage. That is, the material burden of treatment is on the patient's shoulders. Inability to achieve the desired result after all these problems can be disappointing for both the patient and the physician.

Safety Concern 

PRP is an application that was classified as “minimum” in terms of safety concern because the person's own tissue (blood) is used. The regional reaction is very rarely presented. Post-needle pain and some swelling are normal situations to be expected.

In a laboratory study, PRP was found to have antimicrobial properties against bacteria such as S. Aureus and E. Coli. Therefore, there is almost no risk of infection (inflammation).

Numerous scientific studies have been published on the use of PRP in orthopedic problems, especially in the last 5 years. Although the majority of studies indicate that the results are very good, there are some deficiencies. A review published in the British Medical Bulletin in 2009, identified the deficiencies of publications on this subject. The most important of these is the lack of standardization on the amount and types of growth factors in the prepared injection preparate.

In summary, despite all kinds of positive feedback, it should be kept in mind that the results of controlled, random and prospective standardized studies may be different.

Orthopedics and Traumatology Prof. Dr. Hakan Gündeş
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