By Marc Darrow, MD, JD

“We have been told that our 16-year-old son needs PRP injections in both knees. He is an elite track and field jumper. Is this the right treatment?”

My first question would be: what diagnosis has been made in each knee? A jumper with pain at the patellar tendon presents a different problem from an athlete with pain behind the kneecap, a growth-related attachment injury, or a cartilage or bone injury. The sport helps us understand the demands on the knees. It does not, by itself, establish what needs treatment.

PRP may be an option for selected persistent tendon problems, but a recommendation should explain the diagnosis, the evidence, the alternatives, and the rehabilitation required afterward. Being an elite athlete does not make an injection necessary, and treating both knees should have a clear reason for each side.

Jumper’s knee is a possibility, not a diagnosis from the sport alone

Patellar tendinopathy, often called jumper’s knee, affects the tendon connecting the kneecap to the shinbone. Repeated takeoffs, landings, and strength training place substantial demands on this tendon. Symptoms commonly include localized pain near the lower end of the kneecap that increases with tendon-loading activities.

However, front-of-knee pain in an adolescent has a broader differential diagnosis. Patellofemoral pain involves the region around or behind the kneecap. Osgood-Schlatter disease affects the attachment near the upper shinbone. Sinding-Larsen-Johansson syndrome involves the lower pole of the kneecap during growth. Instability and other injuries can also cause anterior knee pain. A pediatric review emphasizes that growth, anatomy, and biomechanics complicate diagnosis and that an examination and appropriate imaging matter. (1)

These conditions should not be grouped together as “overuse” and assumed to respond to the same injection. Pain directly over a tendon is different from pain at its developing attachment or pain arising inside the joint.

The site’s Jumper’s Knee article provides background on patellar tendinopathy. For a 17-year-old, that discussion needs the additional question of skeletal maturity and whether the painful structure is actually the tendon.

Why age matters even in a highly trained athlete

A teenager can have exceptional strength and technique while still having growth-related vulnerabilities. Chronological age alone does not establish whether the relevant growth plates and attachment sites have matured. Training experience also does not eliminate the need to consider an injury involving bone or cartilage.

The evidence gap matters as well. A systematic review specifically examining patellar tendon-related pain in children and adolescents found few usable studies, all at high risk of bias. It supported load modification and symptom-guided return to sport while highlighting the lack of strong evidence for specific interventions. This was not proof that adult treatment protocols should be used unchanged in teenagers. (2)

The review’s search is older, so it should not be treated as a complete account of current research. However, a 2026 review of knee injectables in young athletes reached a related conclusion: evidence remains limited and heterogeneous, with much of it extrapolated from older, nonathletic populations. “Young athletes” also covers a broader population than 17-year-olds with bilateral tendon pain. (3)

The useful question is therefore not simply whether PRP has been studied. It is whether the research matches this athlete’s age, diagnosis, injection location, and intended outcome.

What is PRP, and where would it be injected?

Platelet-rich plasma is prepared from a sample of the patient’s blood. Processing concentrates platelets, which contain substances involved in the body’s response to injury. PRP is not a stem-cell preparation, and it is not a single standardized product.

Preparations vary in platelet concentration, white blood cell content, and other characteristics. Studies also differ in the number of injections, needle technique, and rehabilitation. The biological rationale is interesting, but it does not establish that every PRP protocol repairs a painful tendon.

For patellar tendinopathy, the proposed target may be the abnormal tendon region. An injection into the knee joint addresses a different location. A family should know whether “PRP in the knee” means a tendon injection, a joint injection, or another target—and why that target matches the examination.

Ultrasound can help identify the tendon and guide a needle. Guidance improves knowledge of needle placement; it does not prove that PRP is the best treatment or that the imaging abnormality is responsible for all symptoms. The site’s PRP overview discusses the preparation more generally.

What does the patellar-tendon research show?

The findings are mixed, and the differences between studies should be explained.

A 2019 randomized trial included 57 athletes with chronic patellar tendinopathy. Participants received a single leukocyte-rich PRP injection, leukocyte-poor PRP injection, or saline injection, followed by supervised rehabilitation. Neither PRP preparation produced significantly better pain or functional outcomes than saline. This challenges an assurance that a single PRP injection necessarily adds benefit to rehabilitation. (4)

A smaller randomized trial published in 2024 compared PRP, needle tenotomy, and sham injection in 29 adults, whose average age was approximately 26. All groups improved at one year, with the greatest improvement reported in the PRP group and some accompanying quantitative imaging changes. These are encouraging findings, but the small adult sample cannot establish a predictable result in a 17-year-old or an accelerated return to elite competition. (5)

A 2022 systematic review and meta-analysis also found no significant overall advantage for PRP over other injection treatments for pain and function, although comparisons with shockwave therapy favored PRP for some outcomes. Differences in products, protocols, comparators, and study quality limit a simple “works” or “does not work” conclusion. (6)

Taken together, these studies support an informed discussion about selected persistent cases. They do not establish that every jumper with painful knees needs PRP. They also do not provide a dependable success percentage for this adolescent’s exact situation.

Has rehabilitation addressed the demands of jumping?

“He has already done physical therapy” is useful information, but it leaves questions about what the program involved. A short period of rest, stretching, and passive treatments is different from a progressive program designed to rebuild tolerance for takeoff and landing.

In an adult randomized trial, progressive tendon-loading exercise produced better pain and functional scores at 24 weeks than pain-provoking eccentric exercise. The participants’ average age was 24, so this supports the rehabilitation principle rather than a fixed prescription for every teenager. It also illustrates that recovery can require months of appropriately progressed work. (7)

For a jumper, relevant demands include run-up speed, takeoff force, landing, repeated contacts, and weight-room loading. Training load includes the combined demands of school practice, club sessions, individual workouts, and competition. A rehabilitation plan needs to account for that total exposure.

This does not mean an athlete must stop every activity until entirely pain-free. It means that permitted activity and progression need to fit the confirmed diagnosis and symptom response. A bone stress injury or substantial tear may require a different approach from chronic tendinopathy.

PRP does not remove the need to rebuild strength and sport-specific capacity. If the athlete returns immediately to the same overload, an injection has not corrected that part of the problem.

Does pain in both knees mean both need injections?

Both knees should be assessed individually. Bilateral symptoms may reflect shared training demands, but the location, severity, and underlying condition can differ between sides. One knee may be more symptomatic, and one imaging abnormality may be incidental.

The recommendation should identify the target in each knee and explain why injection is appropriate now. Treating both sides together also has practical implications: temporary soreness may affect walking, stairs, and rehabilitation. The timing and whether treatment is simultaneous or staged are decisions to discuss with the treating clinician, rather than rules that can be set from a brief question.

There is no sound basis for assuming that because one knee may benefit, the other automatically needs the same procedure.

Return to jumping is a functional decision

There is no universal return-to-competition date after PRP. Readiness depends on the diagnosis, symptom response, strength, and the ability to tolerate progressively demanding tasks. Comfortable walking alone does not establish readiness for repeated maximal takeoffs.

When both knees hurt, comparing one leg with the other can also be misleading: similar performance may reflect similar impairment. Assessment should consider the demands of the athlete’s event and appropriate functional measures, rather than symmetry alone.

New substantial swelling, a locked knee, inability to bear weight, or an acute pop followed by difficulty straightening the knee deserves prompt assessment. Fever with a hot, swollen joint requires urgent care. These symptoms should not be treated as ordinary jumper’s knee or managed by simply scheduling PRP.

For this family, the first step is to clarify the diagnosis and the reasoning behind the bilateral recommendation. PRP may deserve consideration for persistent, confirmed patellar tendinopathy after appropriate conservative treatment. It should be presented with the limits of adolescent evidence and a clear rehabilitation plan—not as a necessary procedure solely because the athlete is an elite jumper.

References

  1. Slotkin S, Thome A, Ricketts C, Georgiadis A, Cruz AI, Seeley M. Anterior Knee Pain in Children and Adolescents: Overview and Management. J Knee Surg. 2018;31(5):392–398. doi:10.1055/s-0038-1632376.
  2. Cairns G, Owen T, Kluzek S, Thurley N, Holden S, Rathleff MS, Dean BJF. Therapeutic interventions in children and adolescents with patellar tendon related pain: a systematic review. BMJ Open Sport Exerc Med. 2018;4(1):e000383. doi:10.1136/bmjsem-2018-000383.
  3. Hantouly A, Bedi A, Khan M. Knee Injectables in Young Athletes: Evidence, Recommendations, and Clinical Application. J Bone Joint Surg Am. 2026;108(11):835–841. doi:10.2106/JBJS.26.00267.
  4. Scott A, LaPrade RF, Harmon KG, Filardo G, Kon E, Della Villa S, Bahr R, Moksnes H, Torgalsen T, Lee J, Dragoo JL, Engebretsen L. Platelet-Rich Plasma for Patellar Tendinopathy: A Randomized Controlled Trial of Leukocyte-Rich PRP or Leukocyte-Poor PRP Versus Saline. Am J Sports Med. 2019;47(7):1654–1661. doi:10.1177/0363546519837954.
  5. van der Heijden RA, Stewart Z, Moskwa R, Liu F, Wilson J, Hetzel SJ, Thelen D, Heiderscheit B, Kijowski R, Lee K. Platelet-rich plasma for patellar tendinopathy: a randomized controlled trial correlating clinical outcomes and quantitative imaging. Radiol Adv. 2024;1(2):umae017. doi:10.1093/radadv/umae017.
  6. Barman A, Sinha MK, Sahoo J, Jena D, Patel V, Patel S, Bhattacharjee S, Baral D. Platelet-rich plasma injection in the treatment of patellar tendinopathy: a systematic review and meta-analysis. Knee Surg Relat Res. 2022;34(1):22. doi:10.1186/s43019-022-00151-5.
  7. Breda SJ, Oei EHG, Zwerver J, Visser E, Waarsing E, Krestin GP, de Vos RJ. Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomised clinical trial. Br J Sports Med. 2021;55(9):501–509. doi:10.1136/bjsports-2020-103403.