Platelet rich plasma injections for meniscus tears

Ross A. Hauser, MD., Danielle R. Steilen-Matias, MMS, PA-C. 

In this article, we will explore research on Platelet Rich Plasma therapy for meniscus injury. This article is for people exploring the possibility of:

  • Meniscus arthroscopic surgery.
  • Meniscus arthroscopic surgery with PRP augmentation.
  • PRP injection treatment for meniscus tears as a non-surgical option.
  • Post-surgical treatment help.

Patients will contact our office with questions about their meniscus injury and ask what our recommendations are for treatment. Of course, the best recommendations are made after we perform a physical examination and check for a range of motion, popping and clicking sounds, and catching and other issues of knee instability where the meniscus may be considered a culprit.

The patient may already have an MRI showing a meniscus tear, a recommendation for arthroscopic meniscus surgery, or a history of physical therapy and other conservative care treatments including anti-inflammatories and/or a recommendation from a surgeon that they really need to wait until their knee is worse before an operation can be performed.

One of the treatment options the patient may have researched is platelet-rich plasma therapy or commonly referred to as PRP. PRP is an injection treatment that re-introduces your own concentrated blood platelets into areas of chronic joint deterioration.

Discussion points covered in this article:

  • “Patients treated with PRP injections demonstrated an improving knee function and symptoms over the duration of the study.”
  • Medical reviews of PRP meniscus injections.
  • Platelet Rich Plasma injections have the ability to regenerate tissue.
  • Ten patients with degenerative meniscal tears treated with PRP injections.
  • Five Platelet Rich Plasma Prolotherapy meniscus treatment cases presented in the medical literature.
  • Ross Hauser, MD explains how one injection of PRP will likely not work.
  • PRP injections into the meniscus and around the cartilage.

Can PRP address the problems of a “White Zone Tear”

  • Menisci red zone and white zone. Meniscus tears are characterized by their placement within these two zones.
  • A brief explanation of PRP treatment.
  • Why do we give multiple PRP injections and not a single shot?
  • PRP treatment addresses the ligament instability of a loose knee.
  • The impact of knee instability on squeezing the meniscus out of the knee joint.
  • PRP for meniscus repair, best during surgery or in-office injection?
  • Meniscus arthroscopic surgery with PRP augmentation.
  • Medical reviews of PRP meniscus injections without surgery.
  • Ten patients with degenerative meniscal tears.
  • Five Platelet Rich Plasma Prolotherapy meniscus treatment cases are presented in the medical literature.

“Patients treated with PRP injections demonstrated an improving knee function and symptoms over the duration of the study.”

In March 2022 (1) researchers at the University of Genoa and the University of Salerno in Italy teamed with doctors at Queen Mary University of London and the Keele University of School of Medicine in the United Kingdom to discuss the use of Platelet-rich plasma (PRP) injections as a biologic (non-surgical) option to provide symptomatic relief and possibly delay the need for surgery in patients with degenerative joint disease of osteoarthritis. In this study, the researchers wanted to know if PRP injections could help meniscus tears. Going into the study the researchers did speculate that patients with symptomatic degenerative meniscal lesions without osteoarthritis undergoing autologous PRP injections would experience a significant clinical improvement at 12 months. Their research was published in the medical journal Sports Health.

In this study, a total of 69 patients with symptomatic degenerative meniscal lesions without knee osteoarthritis received 4 autologous (their own blood) PRP injections once a week. Patients were evaluated before the injection and then at one, three, six, and 12 months.

Results: “Patients treated with PRP injections demonstrated an improving knee function and symptoms over the duration of the study. A significant improvement from baseline to 12 months was observed in all the outcome measures, and no patients experienced failure or required surgery during the follow-up.”

Specifically: “Patients younger than 50 years (old) reported lower subjective level of pain and higher Tegner activity scale (less disability) at baseline and had significantly better Lysholm knee scoring scale (looking for improvements in pain, instability, locking, swelling, limp, stair climbing, squatting and need for support.) They also displayed a better range of motion at 3, 6, and 12 months.

  • Thirty-three (47.8%) patients were very satisfied,
  • twenty-six (37.7%) satisfied,
  • eight (11.6%) partially satisfied, and
  • two (2.9 %) not satisfied,
  • with 62 (89.8%) patients willing to repeat the same treatment.

Conclusion: “PRP injections provide short-term benefits in symptomatic degenerative meniscal lesions. Although promising results were evident at 12 months, this is a preliminary study and no definitive recommendation can be made based, for example, on longer follow-up.” In other words, results after 12 months were not studied.

Medical reviews of PRP meniscus injections

Research has shown that the damaged meniscus lacks growth factors to heal. Research has found that injections of PRP bring healing components to the site of the injury.

These components are:

  • platelet-derived growth factor (PDGF), (the components of Platelet Rich Plasma.
  • transforming growth factor (TGF), proteins crucial for tissue regeneration, and others, augment meniscus cell growth and subsequent collagen formation. Collagen is a building block of soft tissue.

Studies with these same growth factors have demonstrated that meniscal tears and degeneration can be stimulated to repair with various growth factors or solutions that stimulate growth factor production. In order to understand how growth factors affect the treatment of meniscus injuries, it is first important to understand the role that they play in the natural process of healing.

  • The preliminary steps of healing begin with the attraction of blood cells to the site of injured tissue.
  • When a tissue is injured, bleeding will naturally occur in that area.
  • A specialized type of blood cells called platelets, rush to the area to cause coagulation, or the clotting of blood cells, to prevent excessive bleeding from an injury.
  • In addition, platelets also release growth factors that are an integral part of the healing process.

Each platelet is made up of an alpha granule and a dense granule. For lack of a better term, these are “vessels” that contain a number of proteins and growth factors that are “poured” out onto the wound or injury. The growth factors contained in the alpha-granule are an especially important component of healing. When activated by an injury, the platelets will change shape and develop branches to spread over the injured tissue to help stop the bleeding in a process called aggregation, and then release growth factors, primarily from the alpha granules.

At this point, the healing process then proceeds in three simple stages: inflammatory, fibroblastic (formation of new connective tissue), and maturation (completion of the healing process).

In the case of the injured meniscus, it is clear that the damaged tissue can not repair itself. Healing in the meniscus depends on having enough blood supply and/or growth factors at the site of the injury. Since less than 20% of the meniscus is vascularized by the time a person reaches the age of 40 years, meniscal healing is generally incomplete.

Platelet Rich Plasma injections have the ability to regenerate tissue

In a recent study, German and Swiss doctors published in the Muscles, Ligaments, and Tendons Journal (2) seeking to demonstrate that Platelet Rich Plasma injections have the ability to regenerate tissue; as already shown in several previous experimental studies.

In this study:

  • Ten recreational athletes with grade II meniscus tears were treated with PRP injections into the affected meniscal area.
  • Three sequential injections in seven-day intervals were performed in every patient.
  • Four of ten patients (40%) showed a decrease in the meniscal lesion in follow-up MRI after six months.
  • Six of ten patients (60%) showed Improvement of NRS-Score at the final follow-up.
  • Average NRS-Score (A numeric scoring system for pain on a 1-10 scale) improved significantly from 6.9 before injections to 4.5 six months after treatment.
  • Six of ten patients (60%) reported an increase in sports activity compared to the situation before injections.
  • In four patients (40%) additional surgical treatment was necessary because of persistent knee pain or progression of the meniscal lesion.

Finding similar results was a March 2022 paper published in the journal Experimental and therapeutic medicine (3) In this paper researchers looked to assess the effectiveness of PRP therapy for patients who have suffered grade 2 meniscal lesions and grade 2 anterior cruciate ligament (ACL) lesions.

  • In 72 young recreational athletes who had been diagnosed with grade 2 meniscal injury benefits were seen from PRP therapy as an enhancement of the primary treatment, after cast immobilization. In terms of pain relief, it appears that PRP therapy could be more efficient for young patients with ACL injuries.

Torn cartilage and Meniscus

Recently, in 2015, doctors at a military hospital in Pakistan treated patients with PRP and published the results: (4) In their paper, they evaluated the clinical effects, adverse reactions, and patient satisfaction after intraarticular injection of platelet-rich plasma in a small group of patients with internal derangements of the knee. (Torn cartilage and Meniscus)

  • 10 patients received two doses of 3 ml of platelet-rich plasma as intraarticular knee injections at two weeks intervals.
  • All patients were evaluated at 0, 4, and 12 weeks after treatment using standard scoring systems
  • There was a significant improvement in all scores.

They concluded that intra-articular PRP injection is a safe and effective method in the conservative treatment of internal knee derangements.

This 2015 paper was cited in June 2022 research published in the International Journal of Environmental Research and Public Health. (5) Here researchers looked at a non-professional athletic population treated with PRP for their meniscus tears. The researchers found: “a positive effect for three PRP intraarticular and percutaneous injections (once a week). . . with pain reduction, health status amelioration, and function improvement at (an average) follow-up of (about) 76 days. The researchers also noted that “after PRP therapy (pain and function scores) achieved significant improvements with a patients’ satisfaction rate of 100% (very satisfied/satisfied) at (an average) follow-up of (about) 76 days, They highlighted “PRP as a reliable and safe alternative to treat stable meniscal lesions and/or to postpone invasive surgical procedures.”

An August 2019 study from Macedonian researchers (6) evaluated the effect of PRP injections in the treatment of knee joint cartilage injuries and degenerative meniscus lesions as well as pain relief.

Here are the summary learning points:

  • PRP procedures were performed on 126 patients, 56 (44.4%) of whom were male, and 70 (55.6%) were female.
  • The patients were evaluated by the Tegner Lysholm Knee Scoring Scale (The patients reported how much pain, instability, knee locking, knee swelling, limp, function in stair climbing, squatting, and the need for walking aids or braces) before applying three doses of PRP for seven days as well as three and six months after the application of PRP.
  • The results showed considerable improvement 3 months after the PRP application, and 6 months after the application the results remained approximately identical.

Conclusion: “The application of PRP in the field of medicine is widely applied, and it will continue to be because the understanding of PRP therapy is increasingly refined. This therapy represents a potential and latest method in short-term pain reduction, but additional studies are needed to prove its long-term effectiveness.” This study stopped its assessment at six months. Other studies mentioned in this article went a little further.

Ten patients with degenerative meniscal tears treated with PRP injections

A March 2020 study published in the Diagnostic and Interventional Imaging (7) described “the preliminary results of intra-meniscal administration of platelet-rich plasma (PRP) in patients with degenerative meniscal tears of the knee.” Basically, the researchers were asking, “Does PRP work?”

Here are the learning summary points of this research:

  • Ten patients with degenerative meniscal tears and without knee osteoarthritis were included.
  • There were 7 men and 3 women with an average age of 40 years old. The youngest patient was 18, the oldest was 59.
  • Patients were prospectively assessed at baseline and three and six months after intra meniscal PRP administration.
  • The evaluation included the knee injury and osteoarthritis outcome score (KOOS), pain visual analog scale, and return to competition and training.
  • MRI follow-up was performed 6 months after PRP administration. Adverse events were recorded.


  • The average KOOS (Knee injury and osteoarthritis outcome score) total score significantly improved.
  • All six patients practicing sports regularly were able to recover from competition or training.
  • In seven patients who underwent MRI follow-up at 6 months, MRI showed stability of the meniscal tears and the possibility of no further meniscus degeneration.

Conclusion: “Intra-meniscal administration of PRP under ultrasound guidance directly into meniscal degenerative lesions is feasible and safe. Further randomized controlled studies are needed to definitely confirm the effectiveness of this procedure.”

Five Platelet Rich Plasma Prolotherapy meniscus treatment cases presented in the medical literature

In our experience, using dextrose Prolotherapy with PRP together enhances the effectiveness of meniscal repair. When treating a meniscal tear with PRP Prolotherapy, the concentrated platelets (PRP) are placed at the site of the tear. Growth factors are released which will stimulate the healing of the tear. The growth factors in the PRP will cause the proliferation and regeneration of the injured tissue. This boosts fibroblastic events involved in tissue healing causing these tears to heal.

In 2010, our Caring Medical research team published our clinical observations on Platelet Rich Plasma Prolotherapy as a first-line treatment for meniscal pathology in the medical journal Practical Pain Management. (8)

In our paper, our goal was to not only show the effectiveness of PRP for meniscal tears but also provide evidence that treating the whole knee for instability by utilizing Prolotherapy, would lead to better PRP results.

Case Report #1
A 21-year-old runner athlete sustained a medial meniscal tear during wrestling. MRI revealed an oblique tear of the posterior horn of the medial meniscus. Because the patient failed physiotherapy and other conservative care the orthopedic surgeon recommended a partial meniscectomy. The patient’s parents were Prolotherapy patients and hoped that Prolotherapy would offer a non-surgical option for their son as well.

  • The patient was complaining of pain with all activities except walking.
  • He had popping in the knee and locking when trying to go from flexion to extension.
  • Physical examination revealed medial joint laxity as well as a positive anterior drawer sign (A test for ACL instability and laxity).

The patient received one session of 3.5cc of platelet-rich plasma Prolotherapy to the inside of the knee. The anterior cruciate ligament and medial collateral ligament were treated with Prolotherapy using a 15% dextrose, 10% Sarapin, and 0.2% procaine solution as previously described.

  • Prior to Prolotherapy, the patient reported pain and stiffness levels of 5 (on a scale of 0 to 10) which decreased to 0 and 1, respectively.
  • Prior to Prolotherapy, he was completely incapacitated related to sports and after Prolotherapy, he was back to running and exercising longer than 60 minutes.
  • When he was questioned 15 months after the PRP Prolotherapy session, he said Prolotherapy had met his expectations.

Case Report #2
A 39-year-old squash player sustained a right knee injury while playing squash about one year prior to the visit. An MRI revealed a horizontal flap tear in the body of the lateral meniscus and the patient had a trial of physiotherapy without success. The patient did not want to get an arthroscopy which was suggested but instead sought out Prolotherapy after an internet search.

  • The patient complained of pain when running and was unable to play sports. He had crepitation in the knee but no locking. He complained of a deep ache within the knee. Physical examination revealed slight medial ligament laxity but no heat or swelling.
  • He received two sessions of PRP Prolotherapy to his knee, each with 3.5 mL of solution. He also received Hackett-Hemwall Prolotherapy to his medial collateral ligament. The patient stated his pain and stiffness levels went from a 6 to a 1 after the prolotherapy. He reported that prior to Prolotherapy he was completely incapacitated from running or playing squash but now, 17 months after his PRP Prolotherapy treatment, he has no limitations.

Case Report #3
A 50-year-old chiropractor sustained medial and lateral meniscal tears after falling in a bicycling accident two years prior. He had tried previous conservative therapy without success in relieving his severe left knee pain. He was completely disabled as far as his previous activities of running and cycling. He did not want to undergo arthroscopy because of a poor response to an arthroscopy on his right knee several years before.

  • Besides pain with any type of activity other than walking, he had popping and crepitation in the knee but no locking. He had pain deep within the knee as well as both laterally and medially. He had some generalized laxity of his knee throughout the physical examination.
  • He received a total of four sessions of PRP Prolotherapy to his knee over a one-year period of time. His general laxity was also treated with Hackett-Hemwall Prolotherapy. The primary reason for such a long time span is that each treatment gave him so much improvement he thought it was his last as he increased his physical activity, only to have some of the pain return. He was contacted twenty-four months after his last PRP Prolotherapy session.
  • Before the Prolotherapy, he had a pain and stiffness level of 8 and 7 respectively, both of which decreased to 1 after Prolotherapy. He was unable to exercise before Prolotherapy but after the PRP Prolotherapy, he is able to engage in unlimited cycling and is able to run, but has chosen not to run because of his right knee (the one that had arthroscopy). He also said that PRP Prolotherapy met his expectations.

Case Report #4
A 52-year-old athlete presented after sustaining an MRI-documented horizontal tear of the posterior horn of the lateral meniscus and an oblique tear involving the postern horn of the medial meniscus after falling during running. He had a past history of partial lateral meniscectomy 20 years prior. His symptoms included diffuse knee pain and a feeling of his knee giving way. He also had occasional locking of the knee.

  • On physical examination, he was found to have medial joint laxity as well as significant crepitation, especially on the medial aspect of the knee. He received a single PRP Prolotherapy treatment for his knee. At that time he also received Hackett-Hemwall Prolotherapy for his medial knee instability.
  • His pain level before Prolotherapy was a 7 and stiffness also a 7 but, fourteen months post-PRP treatment, his pain level is 0 and stiffness is 1.
  • He was unable to exercise at all before Prolotherapy but after treatment, he can cycle for two hours and has no limitations with most weightlifting, all swimming, and all cycling. He cannot run currently because of an Achilles injury that he is thinking about getting treated with Prolotherapy.

Case Report #5
A 46-year-old male with a history of three right knee surgeries and two on the left including partial meniscectomies on both knees presented for a Prolotherapy evaluation because of presumed recurrent meniscal tears on both knees. The patient’s main sport is soccer but had a recent skiing injury that caused bilateral knee swelling and pain for one month prior to the first visit. The patient saw an orthopedist who ordered an MRI which showed the medial meniscal tears.

The patient was adamant about not wanting another knee surgery. He was on nonsteroidal anti-inflammatory medication, which was stopped once PRP was begun. The complaints in both knees (the right was worse than the left) were swelling, popping, and snapping, and the inability to run at all without significant pain. He felt both knees were unstable. The patient was completely disabled in regard to sports because of the injuries.

We have found PRP Prolotherapy to be a dependable and reliable treatment for meniscus tears.

In 2023 our research was cited in a new paper published in the Journal of Advances in Medicine and Medical Research (9). Here researchers from University medical centers in Egypt carried out a study on forty patients with grade 2 meniscus tears. Patients were treated with three ultrasound-guided injections, two weeks apart. The researchers concluded: “There were significant improvements as regard pain assessed by Visual Analogue Scale (VAS), active range of motion (ROM), knee joint line tenderness grading 4 months after treatment compared to before treatment. There was a significant improvement as regard symptoms, Activities of daily living (ADL), pain, sport, and recreation function, and knee-related quality of life (QOL) subscales of Knee Injury and Osteoarthritis Outcome Score (KOOS) four months after treatment compared to before treatment.”

How we utilize PRP to repair your knee. The difference between INJECTION vs. INJECTIONS

Before we get into the research of PRP for Meniscus injury we want to demonstrate, in the videos below how we offer PRP injections. You will notice that the treatment is injections, not AN injection.

In this video, Ross Hauser, MD explains how one injection of PRP will likely not work

We will often get emails from people who had previous PRP therapy without the desired healing effects. We explain to these people that their treatment probably did not work because the single PRP injection did not resolve knee instability. The PRP may have tried to create a patch in the meniscus but the instability and the wear and tear grinding that tears at the meniscus remained.

When a person has a ligament injury or instability, the knee becomes hypermobile causing degenerative wear and tear on the meniscus and knee cartilage. In other words, the cells of the meniscus and cartilage are being crushed to death. When you inject PRP into the knee, without addressing the knee instability, (treating the ligaments,) the injected PRP cells will also be subjected to the crushing hypermobile action of the knee. The single-injection PRP treatment will not work. The knee instability needs to be addressed with comprehensive Prolotherapy around the joint.

This image shows the blood draw and centrifuging in the preparation of a platelet rich plasma treatment for knee pain. This is also known as PRP Therapy
This image shows the blood draw and centrifuging in the preparation of a platelet-rich plasma treatment for knee pain. This is also known as PRP Therapy

Why do we give multiple PRP injections and not a single shot?

In the many emails we get from people looking for information on his/her meniscus tear, we often hear of their meniscus injury, and then we hear about the other structures of the knee that have been damaged. Sometimes we hear about this other damage almost as an afterthought. For instance:

  • “I am scheduled to have meniscus surgery . . . and I have a Baker’s Cyst”
  • “I am scheduled to have meniscus surgery . . . and yes I had an ACL reconstruction a few years ago”
  • “I am scheduled to have meniscus surgery . . . and yes I had a meniscus surgery before, I think for the medial meniscus, this time it is the lateral meniscus.”

A meniscus injury is usually not an isolated injury

  • If the injury is from an impact injury, there is typically enough force to damage or stretch the supporting knee ligaments including the ACL, PCL, and MCL even if an MRI shows “no damage.”
  • If the meniscus tear is from degenerative wear and tear and overuse, the meniscus needs to be treated as A PART of degenerative knee disease. The meniscus cannot be fixed in isolation, the entire knee environment must be addressed to remove pressure from the meniscus and help the meniscus repair.

PRP injections into the meniscus and around the cartilage

A June 2023 study from clinical and university researchers in Spain and Portugal evaluated the effectiveness of applying a combination of intrameniscal (into the meniscus) and intraarticular (into the cartilage) injections of Platelet-Rich Plasma (PRP) in patients with meniscal tears. This research appears in the journal Knee Surgery, Sports Traumatology, Arthroscopy (10). As a brief overview comment, this is a study that in basis is suggesting a more comprehensive PRP treatment approach than the single injection into the knee, as we describe throughout this article).

The researchers examined three hundred and ninety-two cases. This is what they found:

  • Of the 392 cases, thirty-eight patients (less than 105) who eventually went to get surgery, did so after an estimated average treatment of 54.4 months. These people were able to delay surgery for 4.5 years on average.
  • The type of severity of the injury and the presence of chondropathy (degeneration, missing, inflamed cartilage) were risk factors for surgical intervention after PRP treatment
  • The patients were assessed by the  Knee injury and Osteoarthritis Outcome Score (KOOS) system. All outcomes scores showed a significant statistical improvement from baseline to 6 months (in 93 patients) and 18 months (in 66 patients).

The researchers concluded: “The combination of intrameniscal and intraarticular PRP injection is a valid conservative treatment for meniscal injuries avoiding the need for surgical intervention. Its efficacy is higher in horizontal tears and decreases when joint degeneration is present.”

A brief explanation of PRP treatment by Danielle R. Steilen-Matias, MMS, PA-C

  • One of the most common medical conditions we see at Caring Medical is Meniscal tears.
  • We treat patients with Prolotherapy and PRP injections.
  • We inject the PRP into the meniscus tears with ultrasound guidance and then use the dextrose Prolotherapy to treat and strengthen the supportive ligaments of the knee to provide the knee with improved stability. We find that our meniscus tear treatment success rate is greatly helped by focusing on and treating the MCL ligament. Using ultrasound we will examine the integrity of the MCL.
  • Typically a meniscus tear would require 4 – 6 treatments depending on the tear and activity or work demands of the patient.

PRP treatment addresses the ligament instability of a loose knee

The reason patients are seeking out alternatives to conservative care or surgical intervention for meniscus injury is that these treatments have come under intense scrutiny in the medical community for failing to help patients achieve long-term knee repair. The most serious of the long-term consequences is an acceleration of joint degeneration.

  • In brief, in the research, surgeons warn each other that they face the difficult decision of removing or retaining the meniscus during an arthroscopic procedure. If the decision is made to retain the meniscus, the surgeons must address the difficulties of post-operative meniscal healing.

One option is to introduce Platelet Rich Plasma into the surgery. For some of our patients, this is in fact where they heard about PRP for the first time, when a doctor discussed with them surgical possibilities and the use of PRP for accelerated surgical healing.

What are we seeing in this image? The impact of knee instability on squeezing the meniscus out of the knee joint

We use an ultrasound image to demonstrate the motion of the knee. When the knee is bent in one direction, the meniscus is squeezed out of the joint or extruded as you would extrude toothpaste out of a tube. The meniscus belongs within the knee joint. When the knee is in valgus or knock-knee position, the meniscus returns to the confines of the knee joint. This person’s meniscus would pop in and out of the knee on certain motions.  FIXING the meniscus only would NOT prevent the meniscus from popping in and out of the knee. Fixing the knee instability would address this problem.

Can PRP address the problems of a “White Zone Tear”

Many people will email our office and will make a clear distinction about the type of tear they have by using the designation “red zone tear,” or “white zone tear.” More people will say they have a “white zone tear.” Why? Because they have been given the explanation that white zone tears are very difficult to treat and that these tears usually require surgery to cut out the damaged area of the meniscus.

Emails of this nature go something like this:

  • I have a ruptured medial meniscus. It is all in the white zone. MRI says horizontal-diagonal complex tear. Currently getting physical therapy and doing the recommended exercising every day. I still have a lot of knee pain. My orthopedist  said, that it is not possible to repair or regenerate (with PRP injections see below) the white part of the meniscus.) We will answer this below.
  • I have a lot of problems with my knee, I have a Baker’s Cyst that comes and goes that causes a lot of problems. I also have a torn meniscus that I did not know I had. My doctor says my meniscus problem is not good because it is in the white zone and I should have surgery. At this point, the surgery is knee replacement and I can get cortisone injections until I can get a knee replacement.
  • I have a white zone meniscus tear. I have to use a knee brace to get around. I have difficulty with stairs.  Cortisone and hyaluronic acid treatments are no longer effective. I have been researching PRP injections online. I noticed you talk about a more comprehensive strategy. The doctors I have reached out to seem to suggest a single visit or single treatment method and if that does not work, then I should just move on to surgery.

We discuss below why PRP is not a “one-shot wonder treatment,” and should not be thought of in this way. This helps prevent an over-expectation of what one treatment can do and presents a more realistic treatment path to the patient.

Menisci have two zones. The red zone is outside and the white zone is inside. Meniscus tears are characterized by their placement within these two zones.

A red zone tear lies within the blood-rich portion of the meniscus. Where there is a blood supply there is healing as blood brings the healing and growth factors needed for wound repair.

  • The white zone meniscal tear is thought to be non-healing because there is no direct blood supply. 
  • Many doctors do not believe the white zone meniscus tear can be repaired because of this.
  • This is typically the part of the meniscus removed in meniscus surgery.
If you have a red zone tear, there is a chance arthroscopic surgery can go in and sew it up. If you have a white zone tear, it is most likely that your meniscus will be removed. All or some of it. The great majority of meniscus arthroscopic surgeries are to REMOVE meniscus tissue.
If you have a red zone tear, there is a chance arthroscopic surgery can go in and sew it up. If you have a white zone tear, it is most likely that your meniscus will be removed. All or some of it. The great majority of meniscus arthroscopic surgeries are to REMOVE meniscus tissue.

In the research below we will show that when you address the problems of the whole knee, Baker’s cysts, ligament laxity and damage, cartilage deterioration, patella problems, and nephropathy, you can address problems of the white zone meniscus tear without surgery.

In an animal study published in the journal Orthopaedic Surgery (11), researchers investigated the role of autologous (blood taken from the same animal, in this case, a dog, platelet-rich plasma (PRP) on the repair of meniscal white-white zone injury through promoting the proliferation of canine bone marrow-derived mesenchymal stem cells (BMSCs).

What was the point of this study and what were the researchers trying to demonstrate? There were 24 beagles who had a white-white zone injury in both knee joints. The dogs were divided into four groups: control, bone marrow-derived mesenchymal stem cells, PRP, and PRP + bone marrow-derived mesenchymal stem cells. Then the researchers measured the expression of osteopontin (a protein involved in inflammation) in the synovial fluid of the knee joint, the expression of type I collagen (the collagen of bones and skin), and type II collagen (the collagen of cartilage), the healing of meniscus injury, and the damage degree of lateral femoral condyle cartilage.

What the researchers found was that compared to a control group (no treatment), the expressions of type I and type II collagens were enhanced in the PRP group and the PRP + bone marrow-derived mesenchymal stem cells group. The application of PRP alone or in combination with bone marrow-derived mesenchymal stem cells could promote the clinical healing rate of meniscal white-white zone injury.

For more of a discussion on bone marrow-derived mesenchymal stem cells, please see our article Does stem cell therapy for knee meniscus tears and post-meniscectomy work?

In human beings, researchers writing in the journal Cartilage (12) in December 2021 demonstrated the effectiveness of the growth factors found in blood platelets and platelet-rich plasma therapy. Here are some of the learning points of their research:

  • “When symptomatic, (meniscus injury) represents a challenge since arthroscopic surgery provides unpredictable results: recent evidence has shown that partial meniscectomy is not better than conservative management up to 2 years of follow-up, and the removal of meniscal tissue may accelerate osteoarthritis progression toward osteoarthritis.
  • Intra-articular injection of corticosteroids or hyaluronic acid may help in providing temporary symptomatic relief, but no influence should be expected on the quality of the meniscal tissue.
  • Preclinical studies have documented that platelet-derived growth factors may play a beneficial role in stimulating meniscal repair and regeneration by triggering anabolic pathways and stimulating local mesenchymal stem cells from synovium.”

PRP for meniscus repair, best during surgery or in-office injection?

Often a patient will come in for a consultation asking about PRP treatments during an arthroscopic procedure. Why would surgeons be eager to use PRP during the time of surgery? A team of Polish medical researchers helped answer this question in the journal BioMed Research International. (13) These are the learning points:

  • “Meniscus healing has always been a major challenge for orthopedic surgeons. All types of meniscectomies can lead to an increase in the risk of osteoarthritis. “
  • “Clinical studies comparing total and partial meniscectomy have documented the beneficial effects of meniscus preservation (not removing the meniscus tissue). However, only limited data exist and it so far fails to unequivocally support the benefits of meniscal repair over the partial meniscectomy.”
    • Note: The surgical repair procedure to stitch up a torn meniscus does not show more benefit than partial meniscectomy.
  • Although the reoperation rate for partial meniscectomy is significantly lower than for meniscal repair (3% versus 20%), recent studies provided some evidence concerning the benefits of the latter. In the long-term follow-up (10 years) 78% of the patients who underwent the meniscal repair had no radiologic signs of osteoarthritis versus only 63% in the partial meniscectomy group. So, the current practice is to preserve meniscus tissue, with minimal resection.

The most important finding of this study is that PRP augmentation improved the healing rate of complete vertical meniscus tears located in the red-white zone. Additionally, the functional outcomes at 42 months were better in patients treated with PRP-augmented meniscus repair than in those treated with only meniscus repair; however, pain levels were comparable between these patient groups.

What does all this mean to the patient who is exploring treatment for a meniscus tear, especially a tear that extends from the blood-rich meniscus to the blood-deprived meniscus white zone?

  • It is better not to remove meniscus tissue
  • Treating with PRP at the time of surgery helped
  • BUT – this is the BIG BUT – “the functional outcomes at 42 months were better in patients treated with PRP-augmented meniscus repair (at the time of surgery) than in those treated with only meniscus repair; however, pain levels were comparable between these patients groups.” Why the pain? Because the treatment isolated the meniscus and not the whole knee capsule as PRP injections do.

Continue reading the evidence for injection treatment below.

Doctors at the Department of Orthopaedics, Xiangya Hospital, Central South University in China published their research in the journal Medical Science Monitor. (14)

In this research, they discuss the meniscus white-white tears which they describe as “a meniscus lesion completely in the avascular zone (white zone) are without blood supply and theoretically cannot heal.”

They hypothesize that doctors need to get blood to this meniscal zone for healing to occur but face the task that the problem of promoting meniscal healing in the avascular area has not yet been resolved. The possible answer? Platelet-rich plasma (PRP). The Chinese team supports the idea that the application of platelet-rich plasma for white-white meniscal tears will be a simple and novel technique of high utility in knee surgery.

Platelet-rich plasma (PRP) can be the answer for some surgical patients during surgery to address the healing challenges of the “white-on-white” meniscus tear.

So the idea is to bring PRP in during the surgery and apply it to areas where normal blood supply is limited and this should accelerate healing. In theory, should work great. But it does not.

Meniscus arthroscopic surgery with PRP augmentation

There is no question that cartilage heals slowly and poorly this includes the meniscus. Recommendations for surgeries involving shaving or removing the torn portion of the tear using arthroscopic surgery, or sewing the tear together is flawed because it does not repair the deteriorated meniscus.

By failing to heal the damaged meniscal cartilage, surgery does not alleviate the chronic pain that people with this condition experience.

Here is research from the University of Virginia Health System. Here doctors focused on the problem of increased contact stresses in the knee after meniscectomy. (15)

They note that since Platelet-rich plasma has received attention as a promising strategy to help induce healing, the doctors then sought to:

  • evaluate whether PRP augmentation at the time of (surgical) meniscal repair decreases the likelihood that subsequent meniscectomy will be performed; in other words, could PRP prevent the need for a second meniscus surgery?
  • determine if PRP augmentation in arthroscopic meniscus repair influenced functional outcome measures; and
  • examine whether PRP augmentation altered clinical and patient-reported outcomes.

In this study, the experiment was to remove meniscus tissue and see if PRP treatment made a significant impact on the surgical outcome. Before we go on, a quick citation is needed to help with the understanding of the dilution of PRP during surgery.

  • University of South Alabama College of Medicine published in the Journal of Surgical Orthopaedic Advances a troubling study with implications for healing after arthroscopic surgery. These researchers hypothesized that agents injected into the knee during and after knee arthroscopy will be significantly diluted by residual arthroscopic fluid by 27%. (16)

So theoretically, during surgery, a weakened PRP treatment is asked to heal the surgical and meniscal damage

Returning to the University of Virginia Health System research, its conclusion should then not be surprising:

“Patients who sustain meniscus injuries should be counseled at the time of injury about the outcomes after meniscus repair. With our limited study group, outcomes after meniscus repair with and without PRP appear similar in terms of reoperation rate.”

In the two above studies, researchers sought to improve the surgical outcomes in meniscal surgery by applying a PRP solution to the torn meniscus during the procedure. PRP could not be confirmed as effective – the culprit for non-conclusive results was not the PRP but the surgical procedure.

Let’s wrap up this section by reviewing the February 2019 research from the same Polish researchers we cited earlier. This time published in the International Journal of Molecular Sciences. (17)

Here are the learning points:

  • In cases of Meniscal tears, no benefit with surgical treatment is observed.
  • The purpose of this study was to investigate the effectiveness and safety of platelet-rich plasma application to complement the repair of a chronic meniscal lesion.
  • The repair was a meniscal trephination with or without concomitant PRP injection.
    • In this procedure, a hole is drilled through the meniscus tissue to allow blood to flood the damaged area.
  • This double-blind, placebo-controlled study included 72 patients. All subjects underwent meniscal trephination with or without concomitant PRP injection.
  • Meniscal non-union (the failure of the meniscus to regenerate and repair) observed in magnetic resonance arthrography or arthroscopy were considered failures.
  • The failure rate was significantly higher in the control group (70% failure)  than in the PRP augmented group (48% failure).
  • There was a significant reduction in the number of (second) performed arthroscopies in the PRP augmented group.
  • A notably higher percentage of patients treated with PRP achieved minimal clinically significant difference in pain scores.
  • The conclusion of the study indicates that percutaneous meniscal trephination augmented with PRP results in a significant improvement in the rate of chronic meniscal tear healing and this procedure decreases the necessity for arthroscopy in the future (8% vs. 28%).
  • A brief explanation of PRP treatment by Danielle R. Steilen-Matias, MMS, PA-C.
  • PRP treatment addresses the ligament instability of a loose knee.
  • The impact of knee instability on squeezing the meniscus out of the knee joint.
  • Can PRP address the problems of a “White Zone Tear”
  • PRP for meniscus repair, best during surgery or in-office injection?
  • Meniscus arthroscopic surgery with PRP augmentation.
  • The use of PRP during arthroscopic surgery remains controversial.
  • Summary

The use of PRP during arthroscopic surgery remains controversial

A February 2022 paper in the Journal of Orthopaedics and Traumatology (18) from a combined team of European researchers did not find PRP application in arthroscopic meniscal repair helped repair the meniscus any faster. The subject, according to the authors remains controversial.

In a September 2022 paper in the Journal of Orthopaedic Surgery (Western Pacific Orthopaedic Association journal) (19), researchers found similar and somewhat disappointing results of adding PRP during surgical application. “Based on 9 random control studies, the application of PRP in meniscus repair might have a positive effect on patient’s pain score and knee joint function scores at 6 months, and the healing rate at follow-up. However, we don’t find significant improvement in patient’s pain score and knee joint function scores at 1 month and beyond 12 months.”

A March 2022 study from doctors at the Department of Orthopedic Surgery-Sports Medicine Service, Massachusetts General Hospital and published in the journal Knee Surgery, sports traumatology, arthroscopy (20) the following observations following meniscal surgery with PRP augmentation. “Patients reported significant improvements in functional outcomes scores after repair with biological augmentation, though the benefit over standard repair controls is questionable. Revision rates after biologically augmented meniscal repair also appear similar to standard repair techniques.”

An April 2023 paper (21) from doctors at the Department of Orthopaedics, Cedars-Sinai Medical Center, Los Angeles, the University of Florida, Ohio State University Wexner Medical Center, Indiana University, et al.  Wrote: “Evidence supporting (PRP) augmentation of meniscal repair is limited at this time but suggests that the highest likelihood for the effectiveness of augmentation is in the settings of isolated meniscal repair or meniscal repairs that would normally not be amenable to repair.” The last statement suggests that PRP may be more effective for some patients whose meniscus cannot be repaired and who are generally recommended for a form of meniscectomy.

What are we seeing in this image?

The knee in this MRI had prior meniscus surgery. Post-surgical changes in the meniscus are demonstrated because the meniscus is smaller than it should be. Part of the meniscus is missing. This MRI followed another post-surgical MRI which revealed similar meniscus damage. (MRIs after surgery are to confirm the success of the surgery or to look for reasons the patient continues to have). The problem for the radiologist is that he/she cannot tell if this person’s meniscus is still degenerating or if the damage that is in the meniscus now is surgical damage.


Summary and can we help you?

One of the most common calls our office receives involves patients who have had part or all of their meniscus removed and are suffering from continued pain or arthritis that was accelerated due to the surgery. Meniscectomies worsen knee joint instability by negatively influencing other supporting knee structures, increasing contact stress, and leading to arthritis. For those who are considering meniscectomy surgery, we strongly suggest at least a consultation with a doctor who is familiar with Prolotherapy and PRP treatments. We should also point out that regenerative medicine injections such as PRP or Prolotherapy will not regrow a meniscus that has been completely removed. These treatments can help provide stability to the knee to limit stress on the knee and help alleviate a bone-on-bone situation.

If you receive only cartilage cell injections into your knee, you are still going to have bone on bone. Unless there is some meniscus tissue present and enough joint fluid produced by the synoviocytes, bones will still hit and rub, even with articular cartilage present. Furthermore, if there is instability in the joint or the knee cap does not track correctly, the joint will continue to degenerate and the condition will worsen.

While advanced cellular solutions including PRP have provided outstanding patient results, it is important to remember the principles of treating chronic pain with Prolotherapy. The underlying cause of most chronic pain is joint instability. In order for the patient to receive the full benefit, we combine Prolotherapy with the surrounding joint structures as well as use PRP.

If you have questions about your knee pain and how we may be able to help you, please contact us and get help and information from our Caring Medical staff.

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Other meniscus articles:

Should I have meniscus surgery? Reviews of Surgical and Nonsurgical Treatments for Meniscus Tears

The evidence for non-surgical bucket handle meniscus tear repair

Prolotherapy for Meniscus Tears

Arthroscopic knee surgery in a middle-aged patient. Are there non-surgical options?


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This article was update July 1, 2023



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