Patellar tendinopathy (jumper's knee): why does it happen, how is it treated?

Short answer

Patellar tendinopathy ("jumper's knee") is a pain that develops in the tendon just below the kneecap due to repetitive jumping and loading — it is especially common in jumping sports such as volleyball and basketball. The core treatment is progressive tendon loading; the focus is not on reducing inflammation, but on preparing the tendon to bear load again.

A practical framework: isometric exercises (contracting the muscle without movement) can provide rapid pain control and do not require the athlete to stop the activity entirely; then, with heavy-slow resistance or eccentric work, the tendon's capacity is increased. In parallel, load management (regulating jumping volume) is essential. PRP, cortisone, and surgery are not first-line; the evidence places loading treatment first.

Why does it happen?

The patellar tendon connects the kneecap to the shin bone and bears high load during jumping/landing. When repetitive and abruptly increased loading exceeds the tendon's load-bearing capacity, pain and structural change develop. The most important modifiable factor is training/jumping load; it is very common in elite volleyball players.

Treatment: progressive tendon loading

Isometric loading: Contracting the muscle without movement at a specific angle (for example, holding a static position with the knee bent) can reduce pain for a while after the exercise. This is particularly useful during the season — the athlete can continue the activity while managing pain.
Heavy-slow resistance (HSR): Performing each repetition slowly (controlled on the way down and up) strengthens the tendon; it is practical to apply and has high patient satisfaction.
Eccentric work (e.g., controlled squats on a decline surface): one of the most studied methods.

All three approaches are effective; the choice is made according to the individual and the phase. Recovery requires patience and generally takes months.

Load management and "acceptable pain"

Load that exceeds the tendon (jumping volume, sudden increases) is regulated. The modern approach is not "complete avoidance of pain," but the acceptable-pain model: during loading, pain should not exceed a certain level, should not increase markedly after exercise, and should return to baseline by the next morning. If these limits are exceeded, the load is too much and is reduced. In this way the athlete can continue loading safely without entering complete rest.

Shock wave therapy (ESWT)

Extracorporeal shock wave therapy (ESWT) is a needle-free and non-surgical method that stimulates a healing response through pressure waves applied externally to the tendon region. Its role in patellar tendinopathy can be summarized as follows:

The evidence is moderate and mixed: a clear superiority of ESWT over placebo (sham application) has not been demonstrated; however, there are studies reporting significant pain benefit compared with some other conservative treatments.
For this reason ESWT is not first-line — the core treatment is still progressive tendon loading. ESWT is considered more often in refractory (chronic) cases that do not improve despite an adequately applied loading program, and it is generally used together with loading treatment.
Being needle-free and non-surgical makes it a reasonable option that can be tried before surgery. It is generally well tolerated; there may be brief pain during/after application.

PRP, injection, and surgery

PRP: Systematic reviews have not proven PRP's superiority over physical therapy or other injections; it is safe but not first-line.
Corticosteroid: May provide short-term relief but carries a risk of worse long-term outcome than loading and of tendon weakening; it is not recommended.
Surgery: Considered only when a properly applied loading program of long duration (generally ≥6 months) has failed; its superiority over exercise has not been clearly demonstrated.

For clinicians

The evidence on isometric analgesia and HSR is based on small samples and has not been consistently replicated (Rio 2015; Kongsgaard 2009); network meta-analyses show no definitive superiority among modalities. The essential is progressive tendon loading; the isometric, HSR, and eccentric approaches are used according to the phase of the program. The strongest RCT evidence for the "acceptable pain" threshold (≤5/10, return to baseline the next day) comes from the Achilles, and is adapted to the patellar tendon by expert opinion. The risk factor is jumping load; in-season management and off-season capacity building are planned separately. The evidence for ESWT is low-to-moderate: superiority over placebo is not clear, superiority over some conservative treatments has been reported — a second-line option in refractory cases, combined with loading. The commercial popularity of PRP exceeds the strength of the evidence.

Frequently asked questions

The tendon below my kneecap hurts when I jump and squat — what is this?

This is the typical picture of patellar tendinopathy (jumper's knee): pain in the tendon just below the kneecap that increases with jumping/landing and squatting. It is common in jumping sports. The basis of treatment is progressive tendon loading.

Since it hurts, should I rest completely?

Usually no. Complete rest lowers the tendon's capacity even further. The modern approach is to continue loading at the "acceptable pain" limit and to regulate jumping volume. Isometric exercises help manage the pain.

What is an isometric exercise, and what is it for?

It is contracting the muscle at a specific angle and holding it steady without moving (for example, holding a position with the knee bent). This can reduce pain for a while after the exercise and makes it easier for the athlete to continue the activity. Afterward, one progresses to heavier loading that strengthens the tendon.

Will PRP or a cortisone injection fix it?

It is not first-line. PRP's superiority over physical therapy has not been proven; while cortisone may relieve in the short term, it carries a risk of weakening the tendon and may give a worse long-term outcome than loading. The core treatment is progressive tendon loading.

How long does it take to resolve?

Tendinopathy recovery requires patience; it generally takes months and requires adherence to a regular loading program. Early and sudden increases in load can set the condition back; progression must be gradual.

Does shock wave therapy (ESWT) work?

In patellar tendinopathy, ESWT is not first-line; the evidence is moderate and mixed (a clear superiority over placebo has not been shown, but superiority over some conservative treatments has been reported). Because it is needle-free and non-surgical, it can be considered — generally together with exercise — in refractory cases that do not improve despite an adequately applied loading program. The core treatment is still progressive tendon loading.

Scientific references

Malliaras P, Cook J, Purdam C, Rio E. Patellar tendinopathy: clinical diagnosis, load management, and advice. J Orthop Sports Phys Ther 2015;45(11):887-98.
Rio E et al. Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. Br J Sports Med 2015;49(19):1277-83.
Kongsgaard M et al. Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy. Scand J Med Sci Sports 2009;19(6):790-802.
Lian OB, Engebretsen L, Bahr R. Prevalence of jumper's knee among elite athletes. Am J Sports Med 2005;33(4):561-7.
Silbernagel KG et al. Continued sports activity using a pain-monitoring model during rehabilitation. Am J Sports Med 2007;35(6):897-906.
van Leeuwen MT, Zwerver J, van den Akker-Scheek I. Extracorporeal shockwave therapy for patellar tendinopathy: a review of the literature. Br J Sports Med 2009;43(3):163-8.
van der Worp H et al. ESWT for patellar tendinopathy: systematic review (limited superiority of ESWT over placebo, partial superiority over some conservative treatments; second-line in refractory cases). Knee Surg Sports Traumatol Arthrosc / related reviews.

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.