Patellar Tendinosis

The tendon below the kneecap. The patellar tendon runs from the lower tip of the kneecap to the bump at the top of the shin, and it takes the pull of the thigh muscles when you jump, land, squat or climb stairs. Ultrasound shows its thickness, its texture and, with Doppler, blood flow inside it; MRI also shows the fat pad, the small fluid sacs (bursae) and the bone around it.

Tendinosis, tendinopathy, tendinitis. Tendinosis means the tendon’s structure has changed: its fibres are less orderly, and the tissue between them is altered. Tendinopathy is the general word for a painful tendon that is sensitive to load, the condition covered on the patellar tendinopathy page. Tendinitis is the older word; it suggests inflammation alone, which is not the whole picture.

The words around it. These are the terms you are likely to see with it on a knee ultrasound or MRI report.

It shows up in many athletes’ tendons that do not hurt. In 320 painless patellar tendons of elite basketball, netball, cricket and Australian football players, 22 percent of those tendons had a darker (hypoechoic) area on ultrasound, against 4 percent of tendons in people who did not play sport. The figure was 32 percent of tendons in basketball players, and 14 percent of tendons (35 of 250) in athletes who had never had pain at the front of the knee (Cook et al., 1998).

It raises the odds of pain later, but most such tendons stayed painless. Across 16 studies that scanned painless tendons in athletes and then followed them, including 1,156 patellar tendons, about 27 percent of abnormal-looking patellar tendons became painful, and 93.5 percent of normal-looking ones stayed pain-free (Cushman et al., 2025).

It did not predict how people did with rehabilitation. In 76 athletes with jumper’s knee treated with exercise, thickening, calcification, Doppler signal, fibre disruption, fat pad edema and bursitis were each found in about a quarter to four fifths of them. None of these, alone or added together, was linked with how much pain and function changed over 24 weeks (Deng et al., 2026).

It is not a diagnosis by itself. Patellar tendinopathy is recognised by its pattern: pain in one spot at the lower tip of the kneecap that rises with jumping, landing and loaded knee bends. The report can support that picture or point to something else, but it cannot say on its own whether the tendon is the source of your pain. The pain below the kneecap guide covers the other causes of pain in that spot.

The scan can change, but that is not recovery. In a trial of 39 men, heavy slow strength training and a cortisone injection both made the tendon less swollen, with fewer blood vessels seen inside it, over 12 weeks. The strength group kept its improvement at six months; the cortisone group did not (Kongsgaard et al., 2009).

The benefit of exercise was not explained by the scan. In an analysis of a trial of 76 athletes comparing two exercise programs, using complete data from 61, there was no evidence that the extra improvement with progressive tendon loading came from changes in tendon thickness or new vessels on ultrasound (Deng et al., 2025).

It often stays a little abnormal. Three to four years after a 12-week strength program, 28 people had held the function they regained in the first year, yet 43 percent still had an area of Doppler signal and the tendons were still slightly thick on average (Agergaard et al., 2024).

What I take from this. I judge progress by what the tendon lets you do: pain on a single-leg squat on a slope, how it feels the next morning, strength, and the return of running and jumping. A repeat scan is for a specific question, such as a suspected tear or a tendon that is not responding, and that is your doctor’s decision.

Treatment builds how much load the tendon can take. The trials are small: a 2025 Cochrane review of seven trials in 211 athletes rated the evidence for strengthening exercise as low or very low certainty and found no trial against a placebo (Lopes et al., 2025). Exercise is still where the guidelines start (Ophey et al., 2025), but the evidence is not settled.

• Progressive loading. In the JUMPER trial of 76 people with long-standing jumper’s knee, most of whom had tried other treatment, a program that progressed the load on the tendon step by step improved a combined score of pain, function and sport more over 24 weeks than one built on slow lowering (eccentric exercise). Return to sport was 43 versus 27 percent, a difference that could have been chance (Breda et al., 2021).
• Heavy slow strength and slow lowering. In 39 men, heavy slow strength training and slow-lowering squats on a slope both improved symptoms and held at six months, and patients were most satisfied with the heavy slow program (Kongsgaard et al., 2009). In another trial, a moderate weight lifted slowly did about as well as a heavy one (Agergaard et al., 2024).
• Holds. Holding a muscle contraction without moving (isometric exercise) is one way to keep loading the tendon during a season. In 29 jumping athletes who kept playing, pain eased with four weeks of either holds or lifting and lowering a weight, and neither did clearly better than the other; there was no group without exercise to compare with (van Ark et al., 2016).
• Injections. Cortisone gave good early relief that had slipped by six months, while the exercise groups in the same trial kept their gains (Kongsgaard et al., 2009). In 57 athletes, platelet-rich plasma (PRP) followed by heavy slow strength training did no better than a saline injection with the same training, up to a year later (Scott et al., 2019).
• Surgery. A Cochrane review found two small trials: open surgery gave no clinically important benefit over slow-lowering exercise at 12 months, and keyhole surgery may have eased pain more than injections aimed at the new vessels. The certainty was low and harms were not reported (Dan et al., 2019).
• What that means for your report. Tendinosis on a scan is not on its own a reason for an injection or an operation. A loading program comes first. The Dutch guideline suggests adding other treatments only if about 12 weeks of exercise has made no clear difference, and keeps open surgery for a small number of people who have not responded to exercise and the other treatments (Ophey et al., 2025). A surgical opinion comes through your family doctor.

I start with where it hurts and what brings it on. Pain in one spot at the lower tip of the kneecap that rises with jumping, landing and deep loaded squats points to the tendon; pain spread around or behind the kneecap points to the kneecap joint; pain with the knee held fully straight points to the fat pad. In a growing athlete I also check the hips, because a hip problem can be felt in the knee.

On examination I press along the tendon, watch a single-leg squat on a slope and a landing, and test the strength of the thigh, hip and calf. I read the report alongside that, giving more weight to how the tendon behaves than to how it looks. If something points elsewhere, such as a large tear, a bone problem or an inflamed joint, I refer you to your family doctor. I cannot order imaging; when further imaging would change the plan, I flag it and refer you.

The plan builds load in stages: holds when the tendon is irritable or the season is on, slow strength work for the thigh, then jumping and landing before full sport. Jumping is often trimmed for a while rather than stopped, and the next-morning response guides each step. The patellar tendinopathy page sets out the stages in detail.