Patellar Tendinopathy treatments
Ross A. Hauser, MD. Caring Medical Florida
Danielle R. Steilen-Matias, MMS, PA-C. Caring Medical Florida
David N. Woznica, MD. Caring Medical Regenerative Medicine Clinics, Oak Park, IL
- In this article, we will examine research and clinical observations of various treatments for patellar tendinopathy, a degeneration process of the kneecap tendon.
- We will also look at the connection between patellar tendinopathy, continuing degenerative knee ligament damage, and degenerative knee instability that makes it very difficult for a jumper to jump without pain and land correctly.
Understanding points: People will often come into the office with confusion because they have been diagnosed with patellar tendinosis or with patellar tendinitis.
- Patellar tendinitis is inflammation, pain, and swelling.
- Patellar tendinitis occurs, for instance, when a runner has knee pain after a run or someone in a sport that involves jumping suffers a more acute injury, especially a first-time acute injury. On examination, the patella tendon is very sore.
- Patellar tendinosis is pain and weakness without inflammation.
- This is a chronic degenerative condition. If this person/athlete gets cortisone shots in the patellar tendon or they take anti-inflammatories for a very long time the tendinitis (pain and degenerative knee disease symptoms with inflammation) becomes tendinosis (pain and degenerative knee disease symptoms without inflammation).
“I do not want to take more time off from working out”
We get many emails, some of them go like this:
I have been trying to get back to running, I have patellar tendonitis that is not responding. I don’t want to take more time off. The orthopedist I am seeing is prescribing anti-inflammatories, I have been on them for months, stronger doses, I still can’t run. He tells me to rest, I have been resting. I still can’t run. I have had two MRIs. I have patellar tendon inflammation. I knew that, my doctor knew that, but nothing is working for me. Not ice, not yoga, not physical therapy. I am getting quickly out of shape.
Others go something like this.
I am being recommended for surgery. My orthopedist tells me I should have no illusions that I will be the same or better player after surgery. I will just have more better days than worse days. I have no illusions, I play volleyball, I have already had two meniscus procedures and my doctor says the tendinitis is probably a response to my post-surgically weakened knee.
From self-management to doctor’s care. Your knee is not responding.
When someone has knee pain, from whatever the source, a self-management program is usually taken before a trip to the doctor. This will include some type of stabilizing brace or knee sleeve and anti-inflammatory medication. Of course, these are only symptom suppression means to keep swelling down and to give the wearer a false sense of security that the brace will hold their knee together. Education is part of the management plan, a person will usually spend a lot of time online trying to find out what is wrong with their knee and the best course of action they can take. The one suggestion most patients with Jumper’s Knee do not want to follow is “REST.”
If you are reading this article, it is likely that here you are, with knee pain that is getting progressively worse, wearing a sleeve on your knee, and a knee that is becoming much less functional. Shutting down your knee and resting seems the best option now.
Rest did not help. Anti-inflammatories are making your knee worse.
After a few weeks of rest, you are back on your knee and nothing has changed. You still have pain, you still have instability. Now perhaps it is time for a trip to the doctor. For some people, they do not go to the doctor. They continue on with more anti-inflammatories because they want to play. These people are going to “suck it up.”
At the beginning of his article, we discussed the difference between tendinitis and tendinosis – this is why it is important to you.
- Patellar tendinitis is inflammation, pain, and swelling.
- Your body is still trying to heal the knee
- Patellar tendinosis is pain and weakness without inflammation.
- Your body HAS STOPPED trying to heal the knee. You have no inflammation, inflammation, as bothersome and troubling as it is, is the way the body heals damage. If you stop inflammation, you cannot heal.
If you would like to learn about When NSAIDs make pain worse and lead to a worsening joint condition, please read our article When NSAIDs make pain worse.
If you are reading this article, perhaps this is what is happening to you now. You are in this situation because you are looking for the quick fix recovery from patellar tendinopathy.
Research: “no treatments exist for patellar tendinopathy that guarantee quick and full recovery”
This is not what you probably wanted to hear. But let’s look deeply at this. What most researchers warn is that there is no “magic bullet,” single injection or single therapy that will repair this type of knee damage overnight. If you have Jumper’s Knee, you did this type of damage over time, it takes time to repair.
The above statement comes from an October 2017 study in the Clinical Journal of Sports Medicine (1) from the Center for Sports Medicine at the University Medical Center Groningen in the Netherlands. Here is the whole sentence:
“Currently, no treatments exist for patellar tendinopathy that guarantee quick and full recovery. Our objective was to assess which treatment option provides the best chance of clinical improvement and to assess the influence of patient and injury characteristics on the clinical effect of these treatments.”
These were the treatments they tested:
Participants were divided into 5 groups:
- Extracorporeal shockwave therapy (ESWT) (A machine delivers acoustic pressure waves to the affected area) (31 participants),
- ESWT plus eccentric training (Eccentric training is an exercise technique where the return to starting pose is done slowly. For instance, if you perform a knee lift, instead of letting your foot drop back down to the floor quickly, you slowly lower it to build muscle strength. (43 participants),
- Eccentric training (17 participants),
- Topical glyceryl trinitrate patch (Salonpas for instance) plus eccentric training (16 participants),
- and placebo treatment (31 participants).
- In comparison, clinical improvement was significantly higher in the eccentric training group and the ESWT plus eccentric training group compared to Extracorporeal shockwave therapy alone, topical glyceryl trinitrate patch, or placebo.
- The higher training volume, a longer duration of symptoms, and older age negatively influence a treatment’s clinical outcome.
NO CLEAR BENEFIT to any of those treatments.
We do find that eccentric exercise training offered some degree of relief, however, the more exercise the less benefit (not what an athlete wants to hear), the longer the patient had the symptoms and the patients’ age also presented problems.
Take away points:
- Extracorporeal shockwave therapy – the role remains unclear
- Exercise the more important of the treatments, but not too much exercise
- No comparison in this study was made to comprehensive Prolotherapy or Platelet Rich Plasma treatments which will be discussed below.
The research above continues the work from University of Groningen researchers. (2) Earlier the University medical researchers investigated the impact patellar tendinopathy has on a patient’s sports and work performance. Their findings were published in the journal Research in Sports Medicine.
- Reduced sports performance was reported by 55% of their study’s participants;
- 16% reported a reduced ability to work and
- 36% decreased work productivity, with 23% and 58%
The Dutch researchers concluded that the impact of Patellar Tendinopathy on sports and work performance is substantial and stresses the importance of developing preventive measures.
More research on extracorporeal shockwave therapy
In March 2018, publishing in the British Journal of Sports Medicine,(3) a multi-national team of researchers evaluated extracorporeal shockwave therapy (ESWT) in treating Achilles tendinopathy, greater trochanteric pain syndrome, medial tibial stress syndrome, patellar tendinopathy, and proximal hamstring tendinopathy.
- (1) no difference between focused ESWT and placebo ESWT at short and mid-term in patellar tendinopathy and
- (2) radial ESWT is superior to conservative treatment at short, mid and long term in proximal hamstring tendinopathy.
Low-level evidence suggests that ESWT
- (1) is comparable to eccentric training, but superior to a wait-and-see policy at 4 months in mid-portion Achilles tendinopathy;
- (2) is superior to eccentric training at 4 months in insertional Achilles tendinopathy;
- (3) less effective than corticosteroid injection at short term, but ESWT produced superior results at mid and long term in greater trochanteric pain syndrome;
- (4) produced comparable results to control treatment at long term in greater trochanteric pain syndrome; and
- (5) is superior to control conservative treatment at long term in patellar tendinopathy.
The conclusion simply suggests, extracorporeal shockwave therapy may or may not help.
Similar findings were made in an August 2018 study from doctors at the National Taiwan University and Taipei Medical University in Taiwan. They published findings in the journal BioMed Central musculoskeletal disorders (4) in London. The suggestion of their findings is that caution be given in providing ESWT to knee soft tissue disorders. ESWT may or may not work for Patellar tendinopathies.
The main problems with patellar tendinopathy – it is a degenerative disorder rather than an inflammatory disorder – should you have surgery?
If the doctor suggests your problem is due to patellar tendinopathy, you have a problem of the tendon that passes from the quadriceps muscle (the large muscle at the front of the thigh) over the kneecap (patella) to connect to the shinbone (tibia).
Researchers have published recommendations and guidelines for treatment in a paper from December 2016, here is what they say:
- The main problem in patellar tendinopathy is tendinosis, which is a degenerative disorder rather than an inflammatory disorder; therefore, the other popular term for this disease, tendinitis, is not appropriate. Tendinosis – degeneration without inflammation (the body has given up trying to heal this injury), Tendinitis – degeneration with inflammation (the body is trying to heal this injury). As we mentioned above.
- The nonsurgical treatment of patellar tendinopathy is focused on eccentric exercises and often has good results.
- Surgical treatment is indicated for cases that are non-responsive to nonsurgical treatment. Open or arthroscopic surgery can be performed; the two methods are comparable.(5)
As far as the surgical technique goes, doctors from the Department of Orthopedic Surgery and the Department of Physical Medicine and Rehabilitation, Mayo Clinic, Florida State University and the Florida State University College of Medicine, published their findings in the journal Orthopedics. They found open surgery and arthroscopic techniques achieved similar satisfactory results in 81% of patients, respectively. Average time to return to play was 5.6 months and 5 months, respectively.(6)
The unappealing aspects of Patellar Tendinopathy surgery – Average time to return to play was 5.6 months and 5 months. Second: If the surgery fails, it is difficult to fix.
The problem with surgery for the athlete are three-fold,
- one the length of time to recovery is not appealing,
- second, patellar tendinopathy is often a chronic problem.
- Third, if the surgery fails, it is difficult to fix.
This is what a paper from the University of Salerno and the University of London suggested in the journal Sports Medicine and Arthroscopy Review.
- Many patients respond well to conservative treatment, but about 10% of them do not.
- In these cases, surgery is indicated.
- In a small percentage of patients, surgery is unsuccessful. This group of patients presents a major challenge, as options are limited.(7)
Non-surgical bio-treatments Prolotherapy and PRP Therapy
Before we look at the research and explanation discussing the use of injection techniques such as Prolotherapy, Platelet Rich Plasma, and Stem Cell Therapy. Let’s look at a paper from the Rubin Institute for Advanced Orthopedics, Sinai Hospital, Baltimore. It was published in the journal Annals of Translational Medicine,(8) October 2019.
In this paper, various methods of treating common knee injuries is discussed. One section has very good information on the concept of patella and the importance of keeping the patella where it should be in the knee.
“Patellar taping is commonly used in conjunction with manual and exercise therapies in the management of Patellofemoral pain syndrome. Taping is predominately used to help decrease pain. Other studies show it can also help with patellar alignment and muscle activation. As patellar hypermobility has been shown as a predisposing factor for developing Patellofemoral pain syndrome, taping can be indicated to promote patellar positioning and decrease pain. . . .Overall, the effects of taping, are conflicting, with some studies showing no benefit and others unsure of the mechanisms of improvements noted. The positive changes including decreased pain and improved VMO (vastus medialis obliquus, the muscle above the knee used to extend the leg at the knee and to stabilize the patella) function are only short-term but can be helpful with acute management of symptoms with functional activity.”
The goal of tape or brace or surgery, is to get the patella back into place.
In this video David Woznica, MD, of Caring Medical Regenerative Medicine Clinics explains Prolotherapy treatments.
Prolotherapy is the injection of a simple sugar solution, hypertonic dextrose, into and around specific important structures in the knee to stimulate their repair. Many studies have documented Prolotherapy treatments effectiveness
Prolotherapy is a multiple injection technique that is demonstrated in videos below. The treatment stimulates healing and repair of the tendon attachments, the knee ligaments and addresses problems of the cartilage that sits behind the knee cap and in the trochlear groove. When more significant degenerative damage has occurred, we may utilize Platelet Rich Plasma Therapy, the use of your own blood platelets reintroduced into the knee. Below Ross Hauser, MD discusses a case of 70% tear treated with stem cell therapy and Prolotherapy.
- Prolotherapy injections to restore stability to the knee cap will usually take 4 – 6 treatments.
- Patients come back every 4 to 6 weeks as we strengthen the attachments of the patella tendon and the quadricep tendon as well as address the cartilage issues behind the knee cap and in the trochlear groove where the patella slides against the thigh bone.
- Typically I would have patients rest after treatment for 5 – 7 days and then begin a responsible closed chain exercise program that would include squats, leg presses, etc, focusing on strengthening the muscles of the downward motion. I would have the patient avoid exercises that twist the knee and avoid running on uneven or up and down surfaces.
In this video, Ross Hauser, MD explains a Prolotherapy knee treatment as performed at our Caring Medical clinics. This is not typical of the way treatment may be performed in other doctor’s offices.
Video learning and demonstrated points:
- In this video, Ross Hauser, MD is seen demonstrating intra-articular (inside the knee) as well as injections surrounding the outside of the knee.
- In addition to knee osteoarthritis, Prolotherapy injections can help patients with problems that will eventually lead to degenerative knee disease.
- Patellofemoral pain syndrome and patellofemoral tracking problems.
- Weakened and damaged ligaments and tendons and their attachments to the bones and muscles that make the knee work.
- In the video, you see that Dr. Hauser is injecting into the
- The knee’s medial joint line here where the medial collateral ligament is.
- The pes anserine tendon
- The medial patellar retinaculum tendon
- The distal quadriceps attachments
- The lateral joint line where the lateral collateral ligament is located.
- The attachment of the iliotibial band
- The capsular knee ligament attachments
One of my more memorable cases over the course of 30 years doing Prolotherapy and more recently stem cell therapy was a patient who came in and had a 70% tear of their patella tendon.
- At 0:30 Dr. Hauser shows an ultrasound scan revealed a significant tear of the tendon.
- The patient revealed that her orthopedic surgeon described her tendon as “spaghetti” and that she would need arthroscopic reconstruction surgery for her patella tendon.
- This particular person is very, very active. She does triathlons, golfs, runs, and she is very holistic and conservative so they wanted me to treat them with our treatments as opposed to surgery.
- It should be pointed out that a tear this significant does take 6 to 8 months to repair with injection therapy. The patient received multiple PRP treatments and ultimately stem cell treatments into the patellar tendon.
- At 1:15 ultrasound before and after revealing that the tear is repairing. The person is back to playing golf, back to running, back to doing everything that they love. So even really severe tears and this was a 70% tear responded to Prolotherapy with PRP with stem cells and the treatment can be objectively verified and confirmed with ultrasound analysis.
When you have bone spurs in the knee
Research on Prolotherapy and PRP injections
Here is what New York University doctors wrote in the Bulletin of the Hospital for Joint Diseases.
“Due to its common refractory response (non-responsive or difficult to treat) to conservative treatment, a variety of new treatments have emerged recently that include dry-needling, sclerosing injections (Prolotherapy), platelet-rich plasma therapy, arthroscopic surgical procedures, surgical resection of the inferior patellar pole (cutting away tendon tissue at the kneecap), extracorporeal shock wave treatment (as discussed in the other studies cited here), and hyperthermia thermotherapy (exposing the knee to high temperature) in addition to physical therapy.”(9)
Obviously, the list includes treatments that we offer at Caring Medical, Prolotherapy and Platelet Rich Plasma.
Non-surgical solutions to the problem of chronic and recurrent Patellar Tendinopathy
In Germany, doctors supported the New York University findings. Writing in the medical journal Der Unfallchirurg (English: The trauma surgeon), the German researchers suggested that treatment with platelet-rich plasma showed a significantly better outcome when used correctly. Additionally, treatments such as Extracorporeal shockwave therapy, operative treatment and sclerotherapy (Prolotherapy) have also shown positive effects. Treatment with corticosteroid injections and with oral non-steroidal anti-inflammatory drugs (NSAIDs) showed positive short-term effects.(10)
Prolotherapy can treat various knee disorders including problems of the tendons. Prolotherapy Injections of a dextrose solution directed at the weakened tendons and involved ligaments. This causes a mild, localized inflammatory response at the injured area which stimulates a string of healing events, which include an increase of blood supply, an influx of reparative cells, and the deposition of collagen cells. When the collagen matures, it will strengthen and tighten the damaged tendons and ligaments.
PRP and Prolotherapy
- PRP treatment takes your blood, like going for a blood test, and re-introduces the concentrated blood platelets from your blood into areas of chronic joint and spine deterioration.
- Your blood platelets contain growth and healing factors. When concentrated through simple centrifuging, your blood plasma becomes “rich” in healing factors, thus the name Platelet RICH plasma.
- The procedure and preparation of therapeutic doses of growth factors consist of an autologous blood collection (blood from the patient), plasma separation (blood is centrifuged), and application of the plasma rich in growth factors (injecting the plasma into the area.) In our office, patients are generally seen every 4-6 weeks. Typically three to six visits are necessary per area.
In this video, you will notice that PRP as we perform it, is NOT a single injection. It is a comprehensive treatment that addresses problems, weakness, and instability of the whole knee capsule.
The treatment begins at (1:22)
- You are seeing a PRP treatment to the anterior and posterior of the knee (the front and back)
- At 1:33 Here Dr. Hauser is injecting the lateral condyle of the tibia to get to one of the attachments of the anterior cruciate ligament.
- Knee instability is a common condition that causes chronic knee pain so when a person is getting treated for knee instability you have to make sure that the various ligaments that are causing the instability are being treated.
- At 1:57 I’m treating the other attachment of the anterior cruciate ligament and you’ll see that I use quite a bit of PRP when I do treat knee instability with platelet rich plasma.
- Platelet rich plasma is very effective at helping resolve any issues that relate to knee instability especially of the cruciate ligament specifically the anterior cruciate ligament as well as meniscal tears and degenerated meniscus.
- This particular person has knee instability from primarily the anterior cruciate ligament being lax or injured. That injury will also cause instability to occur in the medial lateral collateral ligament so you saw me do the lateral knee now (2:52) I’m doing the medial knee so I’m going to do the attachments of the medial collateral ligament
- (2:55) Here I am also doing the lateral condyle again you can you can hit the attachment of the anterior cruciate ligament unto the femoral condyle both from the front and the back so here I’m doing it from the posterior aspect you have to be careful you can see that I’m going slower posteriorly than I did anteriorly just because there’s some nerves back here.
The most important finding is that PRP injections are statistically better than the control group (ESWT and dry needling) at longer-term (6 months or more) follow-up, suggesting that PRP is an effective and worthwhile treatment for Patellar Tendinopathy.
Doctors at the University of Pittsburgh writing in the Journal of Knee Surgery (11) say athletes and doctors are turning to biomaterials, that is stem cells and blood platelets (PRP therapy). In fact, “They are becoming the mainstay of nonoperative therapy in the high-demand athletic population. The most well-studied agents include platelet-rich plasma (PRP) and stem cells-both of which have shown promise in the treatment of various conditions. Animal and clinical studies have demonstrated improved outcomes for patients with chronic patellar tendinopathy.”
In a one-year study of patients who decided on non-surgical PRP treatments to get them back to their sport, European doctors found that all 20 patients in their study benefited from one injection of PRP coupled with a standardized eccentric rehabilitation (exercise). They concluded: “This study confirms that a local injection of PRP coupled with a program of eccentric rehabilitation for treating a chronic jumper’s knee, improves pain symptoms and the functionalities of the subjects’ knee up to 1 year after injection.”(12)
The most important finding in our meta-analysis is that PRP injections are statistically better than the control group (ESWT and dry needling) at longer-term (6 months or more) follow-up suggesting that PRP is an effective and worthwhile treatment for Patellar Tendinopathy.
Doctors in the United Kingdom writing in the journal Knee Surgery and Related Disease (13) released their study in which they state: “The most important finding in our meta-analysis is that PRP injections are statistically better than the control group (ESWT and dry needling) at longer-term (6 months or more) follow-up suggesting that PRP is an effective and worthwhile treatment for Patellar Tendinopathy.”
Multiple Injections of PRP may hold the answer
Doctors at The Rizzoli Orthopaedic Institute in Italy published their paper: Nonsurgical Treatments of Patellar Tendinopathy: Multiple Injections of Platelet-Rich Plasma Are a Suitable Option: A Systematic Review and Meta-analysis. It appeared in the March 2018 issue of the American Journal of Sports Medicine.(14)
What they were looking for was the evidence on nonoperative options to treat chronic patellar tendinopathy: Three treatments came to the forefront as the most studied: They are mentioned in the research above:
- eccentric exercise,
- extracorporeal shockwave therapy (ESWT),
- and platelet-rich plasma (PRP).
- Single and multiple PRP injections were evaluated separately.
“Eccentric exercises may seem the strategy of choice in the short-term, but multiple PRP injections may offer more satisfactory results at long-term follow-up and can be therefore considered a suitable option for the treatment of patellar tendinopathy.”
In December 2018, doctors at the University of Connecticut Health Center published this summary on the effect of PRP on Patellar tendinopathy in the journal Current Reviews in Musculoskeletal Medicine.(15)
The summary of their findings suggested:
- PRP has become a common non-surgical intervention for Jumper’s knee in recent years
- Research indicates that overall, patients had significant improvement in pain and function, with up to 81% of patients able to return to their pre-symptom level of activity. However it should be noted that these results are at the high end of inconsistent findings. Another study suggested 22% were able to return to their pre-symptomatic activity.
- Compared to extracorporeal shockwave therapy, PRP had a significant impact on pain and function
- The number of PRP injections has also been shown to have an effect on the outcome of the treatment, with two injections found to improve outcomes significantly more than a singular injection.
A quick word on Patellar Tendinopathy and ligament weakness
- Chronic patella pain and tendinosis are rooted in knee instability. Upon examination, we find patients who have patellar tendinitis may have laxity in the anterior cruciate ligament (ACL), medial collateral ligament (MCL) or a posterolateral ligament injury.
- The ligaments are the primary stabilizers of the knee. If the knee is unstable, the patellar tendon will be under strain and weaken.
To address this, a series of injections are placed at the tender and weakened areas of the patella tendon and knee ligaments. These injections contain a proliferant to stimulate the body to repair and heal by inducing a mild inflammatory reaction. The body heals by inflammation, and Prolotherapy stimulates this healing. As the ligaments tighten and the patella tendon heals, the knee structures function normally rather than moving out of place. When the knee functions normally, the pain goes away.
If you have questions about Patellar Tendinopathy treatment options, get help and information from Caring Medical
1 van Rijn D, van den Akker-Scheek I, Steunebrink M, Diercks RL, Zwerver J, van der Worp H. Comparison of the Effect of 5 Different Treatment Options for Managing Patellar Tendinopathy: A Secondary Analysis. Clin J Sport Med. 2017 Oct 10 [Google Scholar]
2 De Vries AJ, Koolhaas W, Zwerver J, Diercks RL, Nieuwenhuis K, Van Der Worp H, Brouwer S, Van Den Akker-Scheek I. The impact of patellar tendinopathy on sports and work performance in active athletes. Research in Sports Medicine. 2017 Apr 9:1-3. [Google Scholar]
3 Korakakis V, Whiteley R, Tzavara A, Malliaropoulos N. The effectiveness of extracorporeal shockwave therapy in common lower limb conditions: a systematic review including quantification of patient-rated pain reduction. Br J Sports Med. 2018 Mar 1;52(6):387-407. [Google Scholar]
4 Liao CD, Xie GM, Tsauo JY, Chen HC, Liou TH. Efficacy of extracorporeal shock wave therapy for knee tendinopathies and other soft tissue disorders: a meta-analysis of randomized controlled trials. BMC musculoskeletal disorders. 2018 Dec;19(1):278. [Google Scholar]
5 Figueroa D, Figueroa F, Calvo R. Patellar Tendinopathy: Diagnosis and Treatment. J Am Acad Orthop Surg. 2016 Dec;24(12):e184-e192. [Google Scholar]
6 Stuhlman CR, Stowers K, Stowers L, Smith J. Current Concepts and the Role of Surgery in the Treatment of Jumper’s Knee. Orthopedics. Nov 1 2016;39(6):e1028-e1035. doi: 10.3928/01477447-20160714-06. [Google Scholar]
7 Maffulli N, Giai Via A, Oliva F. Revision Surgery for Failed Patellar Tendinopathy Exploration. Sports Med Arthrosc. 2017 Mar;25(1):36-40. [Google Scholar]
8 Mellinger S, Neurohr GA. Evidence-based treatment options for common knee injuries in runners. Annals of translational medicine. 2019 Oct;7(Suppl 7). [Google Scholar]
9 Christian RA, Rossy WH, Sherman OH. Patellar tendinopathy – recent developments toward treatment. Bull Hosp Jt Dis (2013). 2014;72(3):217-24. [Google Scholar]
10 Horstmann H, Clausen JD, Krettek C, Weber-Spickschen TS. Evidence-based therapy for tendinopathy of the knee joint: Which forms of therapy are scientifically proven? Unfallchirurg. 2017 Mar;120(3):199-204. [Google Scholar]
11 Kopka M, Bradley JP. The Use of Biologic Agents in Athletes with Knee Injuries. J Knee Surg. 2016 Jul;29(5):379-86. doi: 10.1055/s-0036-1584194. Epub 2016 May 20. [Google Scholar]
12 Kaux JF, Bruyere O, Croisier JL, Forthomme B, Le Goff C, Crielaard JM. One-year follow-up of platelet-rich plasma infiltration to treat chronic proximal patellar tendinopathies. Acta Orthop Belg. 2015 Jun;81(2):251-6. [Google Scholar]
13 Dupley L, Charalambous CP. Platelet-Rich Plasma Injections as a Treatment for Refractory Patellar Tendinosis: A Meta-Analysis of Randomised Trials. Knee surgery & related research. 2017 Sep;29(3):165. [Google Scholar]
14 Andriolo L, Altamura SA, Reale D, Candrian C, Zaffagnini S, Filardo G. Nonsurgical Treatments of Patellar Tendinopathy: Multiple Injections of Platelet-Rich Plasma Are a Suitable Option: A Systematic Review and Meta-analysis. The American journal of sports medicine. 2018 Mar 1:0363546518759674. [Google Scholar]
15 Kia C, Baldino J, Bell R, Ramji A, Uyeki C, Mazzocca A. Platelet-rich plasma: Review of current literature on its use for tendon and ligament pathology. Current reviews in musculoskeletal medicine. 2018 Dec 1;11(4):566-72. [Google Scholar]