Part of Patellar tendinopathy
Does patellar tendonitis show up on an MRI, and do you need a scan?
Warning signs, and when to get help
Does patellar tendonitis show up on an MRI?
Usually it does, and the honest next sentence is that this helps you less than you would expect.
On MRI the tendon looks thicker than it should and its signal is changed, most often right at the lower tip of the kneecap. Ultrasound shows much the same thing. If you have a report in your hand using words like thickening, increased signal, tendinosis or neovascularity, that is what it is describing.
Here is the catch, and it comes from the clinical commentary that most physios work from for this tendon. Malliaras and colleagues (2015) state that imaging of the patellar tendon does not confirm patellar tendon pain, because the changes seen on ultrasound can be present in people with no symptoms whatsoever. They go further and say serial imaging is not recommended, since symptoms often improve without any matching change on ultrasound or MRI. The diagnosis stays clinical.
So a scan can find the tendon. What it cannot do is tell you that the tendon is why your knee hurts, and that distinction is what decides whether a scan is worth having.
What the scan actually shows
It shows structure, which is only one of the things that produce pain.
Docking and colleagues (2015) set out the wider difficulty across tendons. Imaging tells you that structural disorganization is present and roughly how extensive it is, and that amount does not line up neatly with how a person feels. They draw the comparison with osteoarthritis and with disc degeneration in the spine, two other places where the picture and the patient part company often enough that clinicians stopped treating the picture. Tendons behave the same way.
That is why two people can have near identical reports and completely different knees. One has been jumping on it for a year and barely notices. The other cannot climb stairs. The tissue change is real in both, and it is not the measure of the problem.
Why a scan rarely changes the plan
Because the treatment is the same whether or not you have the picture.
For a tendon that hurts at the bottom tip of the kneecap and gets worse the harder the thigh works, the plan is a staged loading program: held contractions while it is irritable, heavy slow strength work as the main course, then springy jumping work, then the sport. Our patellar tendinopathy program sets that out in stages. A scan showing a thickened tendon does not change which stage you start at. Your symptoms and what you can tolerate do that.
There is a cost to the scan that is easy to overlook, and it is not the money. A report describing degeneration, tearing within the substance of the tendon or chronic change reads like a verdict, and people tread more carefully afterwards than they did before. Given that under loading is one of the commoner reasons a tendon stays sore, a frightening report can quietly make things worse. Why your patellar tendonitis is not healing goes into that pattern.
Abnormal tendons in people with no pain
This is the finding that explains everything above, and the part people miss comes after it.
Changes of the kind a radiologist reports in this tendon are found in people with no knee pain at all, which is Malliaras and colleagues' reason for saying that imaging does not confirm the source of pain. That alone is enough to stop a scan being a diagnostic test.
The sharper edge is this. McAuliffe and colleagues (2016) pooled prospective studies of people who had no symptoms when they were scanned, and found that an abnormality on ultrasound was associated with developing tendon symptoms later, with a relative risk of 4.97 across both the Achilles and the patellar tendon, and 4.35 for the patellar tendon alone. So a pain free abnormal tendon is not meaningless.
Read the population before you do anything with that. Those were mostly athletes, scanned while pain free, and the authors are explicit that factors beyond tissue structure are involved in how tendinopathy develops. It is a screening observation about groups of athletes, not a reason to scan a knee that is already sore, and certainly not a prediction about one person's next season.
There is one more thing an abnormal report is not. It is not a reason for an operation, and it is not notice that the tendon is about to give way. The American Academy of Orthopaedic Surgeons does say that patellar tendinitis weakens the tendon and that a weakened tendon is more likely to tear, so the words on the report are not nothing. The same source also says a tear takes a very strong force, with the knee bent and the foot planted, landing from a jump or jumping up, or a direct blow from a fall.
A tear arrives as an event you can date, not as a line in a report, and nobody operates on the line in the report. If you want to know what to watch for instead, it is the warning list at the foot of this page.
When does a scan change things?
Three situations, and knowing them lets you ask for a scan at the point where asking makes sense.
The first is genuine diagnostic uncertainty. Malliaras and colleagues note that imaging can help include or exclude alternative diagnoses of front of knee pain, and the front of the knee is crowded.
Patellofemoral pain gives a more spread out ache around or behind the kneecap. A fold of joint lining, called a plica, can be painful even in shallow bending such as walking, which is unlike a tendon. Bone, joint and growth plate problems all live nearby. If the picture does not fit, a scan is a sensible way to narrow it.
The second is a suspected tear, which is dealt with below and has its own urgency.
The third is an operation. If surgery is being considered, the surgeon needs to see what they are dealing with, and that is their call rather than a general rule. Nothing further down this page about scans adding little applies to a scan requested as part of planning an operation.
Notice what is not on the list: confirming a diagnosis the examination already made, and tracking progress.
MRI or ultrasound?
Both show this tendon, and neither makes the diagnosis, so the choice is a clinical and practical one rather than something to push for.
Malliaras and colleagues refer to tendon pathology being seen on ultrasound and on MRI, and to symptoms improving without change on either. Which one you are offered depends on what the clinician is trying to answer, what is available where you live and how the system you are in works. MRI gives a wider view of the joint, bone and surrounding soft tissue, which matters when something other than the tendon is in question.
What is worth bringing to that conversation is the question, not the preferred machine. Saying what you want to know, whether it is a tear, whether something else is going on, whether surgery is an option, gets you a more useful scan than asking for a scan.
How the diagnosis is actually made
Two features, a finger and a load test.
Malliaras and colleagues name the hallmarks plainly. First, pain localized to the inferior pole of the patella, which in plain words is the bottom tip of the kneecap, not the whole joint and not the bump on the shin. Second, load related pain that increases with the demand on the knee extensors, and particularly in activities that store and release energy in the tendon, which means jumping, landing, bounding and changing direction. Where jumper's knee hurts goes through finding that spot and the four places people confuse it with.
The load test commonly used is a single leg decline squat, done with an upright torso to 90 degrees of knee bend or to whatever angle pain allows. The same authors describe progression in terms of what the tendon tolerates: minimal pain during the exercise, and pain on load testing returning to baseline within 24 hours.
None of that needs a machine, which is why a careful examination usually settles this in one appointment. It also explains why a scan ordered before anyone has pressed the tendon tends to produce more questions than answers.
Why repeat scans are not recommended
Because the picture lags behind how you feel, and watching the lagging indicator is a poor way to run a rehab program.
Malliaras and colleagues are direct about it: serial imaging is not recommended, because symptoms often improve without corresponding change in the pathology on ultrasound or MRI. A reader who scans every three months to see whether the tendon is healing will find an unchanged report beside a knee that is clearly better, and the natural response, that the improvement is not real, is wrong.
Track the things that move. A load test done the same way at the same time of day. The next morning response, which our pain monitoring model guide explains. And a questionnaire score, of the kind described in our guide to outcome measures in physical therapy. Those will tell you in three weeks what a repeat scan will not tell you in six months.
The same boundary set out above applies here, and it is worth being exact about, because it is easy to carry too far. What is not recommended is scanning the same tendon over and over to watch it change through a course of loading. It says nothing about a scan a surgeon asks for when an operation is being considered, which is answering a different question: what the tendon looks like now, and what they would be working on. That decision belongs to the surgeon, and turning down their scan on the strength of a page about rehab imaging would be the wrong use of all of this.
What a normal scan does not rule out
A clean report is good news and it is not a discharge letter.
Because the diagnosis is clinical, a tendon that images normally in someone with both hallmark features is still treated as a tendon problem. Docking and colleagues (2015) put the same point the other way round: a relatively normal tendon does not rule the tendon out as the source of the pain. The scan has not overruled the examination. Equally, a normal looking tendon says nothing about the other things that cause pain at the front of the knee, and a reader who leaves with nothing wrong on the scan and a knee that still hurts has been given a result rather than an answer.
The same logic runs in the other direction for the rest of the knee. A report may mention findings in the joint, the cartilage or the meniscus that have nothing to do with your symptoms. Knee osteoarthritis and meniscus tear both produce incidental findings on scans of people whose pain is coming from somewhere else, and whether patellar tendonitis or a meniscus tear is the problem is sorted mainly by history and examination rather than by imaging.
Scans when a tear is suspected
This is the one version of the question with a clock on it, and it is the reason the warning list at the foot of this page leads with a tendon rupture.
A complete patellar tendon tear is largely recognized without a scan. The American Academy of Orthopaedic Surgeons describes an indentation at the bottom of the kneecap where the tendon tore, and the kneecap moving up into the thigh because it is no longer anchored to the shinbone. With the tendon separated from the kneecap you cannot straighten the knee, and that test means straightening it yourself, lifting the leg out straight and holding it there against gravity. Being able to push the knee straight with your hands does not rule a tear out, and neither does walking: the same source describes difficulty walking because the knee buckles, not an inability to walk at all.
Imaging in that situation is quick and practical rather than diagnostic. A side view X-ray shows the kneecap sitting out of position, and the same source says complete tears can often be identified from those X-rays alone. An MRI shows how much of the tendon is torn and where, which is what a repair gets planned from, and it is sometimes needed to rule out a different injury with similar symptoms. None of that is yours to arrange.
If that is what has happened, this is not a page to read further and it is not a scan to organize. It goes to an emergency department straight away, even if you can still walk, and not driving yourself. Waiting costs more than comfort here.
People who need surgery do better when the repair is done soon after the injury, and early repair may stop the tendon scarring and tightening into a shortened position. Tendons often shorten once more than a month has passed, and a tendon that has shortened too far is hard to re-attach to the kneecap, so the surgeon may have to lengthen it with a tissue graft, sometimes donated tissue. A straightforward reattachment turns into a bigger operation, which is what the clock on this one is really about. Can patellar tendonitis lead to a tear covers what raises that risk and what the first hour looks like.
If you have had a repair already, imaging around that operation belongs to your surgical team, and anything new in an operated knee goes to them the same day rather than into a scan request. One change deserves naming, because it does not feel like an event and so it tends to get saved for the next appointment: a knee gradually getting further from straight, or a leg you can no longer hold out straight when you could a week or two ago, with no pop and no single moment you can point to. A repair can stretch out slowly instead of giving way all at once, and the only outward sign is a widening gap between how straight someone else can move your knee and how straight you can hold it yourself. Re-tear and detachment of the tendon from the kneecap are both on the Academy's list of complications of this repair, with weakness and loss of motion the commonest. That is a phone call to your surgical team, not a scan request.
Who to ask about a scan
The clinician who examined the knee, because the value of a scan depends entirely on the question it is being asked.
In most systems imaging is requested by a doctor, and in some a physiotherapist can refer directly. Either way the useful conversation starts from what is unclear. If your examination produced both hallmark features and the plan is a loading program, a reasonable clinician will often say that a scan would not change anything, and that is not them fobbing you off.
Ask three things if you are unsure. What would a scan show that we do not already know. What would we do differently depending on the result. And what are we treating in the meantime.
If the honest answers are nothing, nothing and this program, you have your decision. If you are not satisfied, a second opinion is always reasonable, and our guide to red flags in physiotherapy sets out the findings that should prompt further investigation regardless of anyone's view on imaging.
When to see a physio or a doctor
Book an assessment with a physio (physical therapist) if the knee has not improved in a few weeks, if it is keeping you out of training, or if nobody has yet told you where the pain is coming from. The NHS line is to see a GP when knee pain has not improved in a few weeks, and in many places you can book physiotherapy without a referral.
Go sooner, and to a doctor the same day, if the knee locked, gives way, or is hot and red. Two things do not wait for an appointment at all. A knee that swelled up within a few hours of a twist, a fall or a blow, or where you felt something pop or tear below the kneecap, and a knee you cannot hold out straight yourself, both go to an emergency department straight away, even if you can still walk, and not driving yourself. Those are the findings a scan might actually be needed for, and they are the ones with a timing attached. Every one of them is on the warning list below with how soon it needs attention.
For a growing child or teenager, pain below the kneecap usually comes from a growth center rather than from the tendon, and a different set of warning signs applies. Have it assessed before starting anything. Nothing here replaces an examination: this is what the published evidence says a scan of this tendon can and cannot settle.
Related exercise programs
Warning signs
Get emergency help now
- Emergency: you felt a sudden pop or tearing feeling just above or below your kneecap, you can see or feel a dip there, the kneecap seems to have moved up toward the thigh or to sag lower than usual, or you suddenly cannot straighten your knee or lift your leg out straight. Stop exercising and go to an emergency department straight away, even if you can still walk, as this can be a torn tendon at the front of the knee, either below the kneecap (patellar tendon) or above it (quadriceps tendon). Do not drive yourself. A repair usually does better if it is done soon after the injury.
- Emergency: the knee has moved out of place, looks misshapen or is pointing at an odd angle, or you have tingling or no feeling in the knee, leg or toes, or your foot turns cold, pale or blue. Go to an emergency department straight away. Do not drive yourself: ask someone to drive you or call an ambulance.
- Emergency: the knee became very swollen very quickly, within a few hours of a twist, fall or blow, or you felt a pop or snap. Go to an emergency department straight away. Do not drive yourself: ask someone to drive you or call an ambulance.
- Emergency: the kneecap has slipped out of place, even if it went back by itself. If it is still out of place, go to an emergency department straight away, and do not drive yourself. If it went back by itself, get medical advice the same day.
- Emergency: you are still growing and have pain that wakes you at night, pain at rest that keeps getting worse, or a lump or swelling around the knee or thigh that keeps growing. If you also have a rash that does not fade when you press it, call emergency services or go to an emergency department.
Get help now, day or night
- Your tendon pain or swelling started while you were taking a fluoroquinolone antibiotic, such as ciprofloxacin or levofloxacin, or in the months after a course. Contact your doctor straight away. The UK medicines regulator (MHRA) advises stopping the antibiotic at the first sign of tendon pain or swelling and talking to your doctor. Hold off the knee exercises until you have been checked.
Get help today
- Same day: the pain started with a fall, a twist or a blow to the knee, or you cannot put weight on the leg. Get medical advice the same day.
- Same day: the knee is locked, which means it is stuck bent and you cannot fully straighten it, even after gently trying to move it, or you cannot bend or straighten the leg at all. Get assessed the same day by a doctor, at urgent care or at an emergency department. A torn piece of meniscus can get caught in the joint and block it, and when a tear like this can be repaired, it should be done as early as possible. A knee that catches for a moment and then frees itself can happen with a meniscus tear. That is not the same as a locked knee, but tell your physio or doctor about it.
- Same day: the knee keeps giving way under you, or it gave way after a recent injury, or it gives way and is also very painful or swollen. Get medical advice the same day. If it only happens now and then, with no recent injury and no swelling, it is not an emergency, but book an assessment with a physio or doctor in the next few days.
- Same day: the knee swells up with no clear reason, especially if you take medicine to thin your blood. Get medical advice the same day.
- Same day: a leg or foot that is getting weaker, for example your foot drags, catches on the ground or slaps down when you walk (foot drop). Get medical advice the same day. If the weakness is getting worse by the hour, go to an emergency department.
- Same day: the knee is hot, red and swollen, or you have knee pain with a high temperature or feel hot, cold or shivery. Get medical advice the same day, and go to an emergency department if you feel very unwell. This can be a sign of infection in the joint, which needs treatment quickly.
- Same day: since your operation, your wound is oozing, leaking or has pus coming out of it, or its edges start to come apart, or your knee is tender, swollen, painful or red and it is not getting better or is getting worse, or you have a high temperature or feel hot and cold or shivery. Redness can be harder to see on brown or black skin. Contact your surgical team the same day, or get urgent medical advice if you cannot reach them. These can be signs of an infection in the wound or the knee joint. If you feel very unwell, go to an emergency department. If you have a very high or very low temperature, shivering you cannot control, you are breathing very fast or finding it hard to breathe, you are confused or your speech is slurred, your skin, lips or tongue look blue, gray, pale or blotchy (on brown or black skin this can be easier to see on the palms of the hands or soles of the feet), or you have a rash that does not fade when you press it, call emergency services, as this can be sepsis.
- Same day: after a repair of a tendon at the front of the knee, your knee is gradually getting further from straight, or you can no longer hold your leg out straight when you could a week or two ago, and there was no pop and no single moment you can point to. Contact your surgical team the same day rather than waiting for your next appointment. A repair can stretch out gradually instead of giving way all at once, and this is what that looks like. Keep to what your surgical team has already allowed you to do, and do not move on to a new exercise or a new stage until you have been seen.
- Same day: a calf or thigh that is newly swollen or getting more swollen, warm, tender, red or darker than usual, has swollen veins that are sore to touch, or has a throbbing or cramping pain that does not fit your injury or condition, or that feels different from normal muscle soreness after exercise. This can be a sign of a blood clot (deep vein thrombosis), especially after surgery, an injury, time in a cast or boot, a long trip or a spell of being much less mobile than usual. Get medical advice the same day. If you are also short of breath or have chest pain, call emergency services.
- Same day: you are a teenager who is still growing and you have a limp, or pain in the hip, groin or thigh as well as the knee. Get an urgent appointment with a doctor the same day, and stay off sport and these exercises until you have been checked. If you cannot put weight on the leg, have a high temperature or feel very unwell, go to an emergency department. Some hip problems in growing teenagers, such as a slipped growth plate at the top of the thigh bone (slipped capital femoral epiphysis), are felt in the knee and need checking quickly.
- Same day: pain at night or at rest that keeps getting worse. If you are being treated for cancer now, contact your cancer team the same day.
Book an appointment
- Within a day or two: you are still growing and have pain that wakes you at night, pain at rest that keeps getting worse, or a lump or swelling around the knee or thigh that keeps growing. See a doctor within a day or two. Ask for an urgent appointment rather than the next routine one, and say what the pain does at night and whether a lump is getting bigger. Do the same if the pain comes with looking pale, unusual tiredness, fevers with no clear cause, bruising or bleeding easily, or weight loss. Bone pain that is worse at night, or a new lump, needs checking to rule out rarer causes such as a bone tumor or a blood cancer (leukemia).
- Within a day or two: pain at night or at rest that keeps getting worse. If you have had cancer, now or in the past, see your doctor sooner, within a day or two, and mention it, even if the pain is not getting worse. Do the same if you have knee pain and are losing weight without trying, even if it does not hurt at night.
- Within a few days: pain at night or at rest that keeps getting worse. See your doctor within a few days.
Common questions
Does patellar tendonitis show up on MRI?
Usually, yes. The tendon looks thickened and its signal is altered, most often at the lower tip of the kneecap where the condition starts. Malliaras and colleagues (2015) make the point that this is not the same as a diagnosis: imaging of the patellar tendon does not confirm that the tendon is causing the pain, because the same changes appear in people with no symptoms. Docking and colleagues (2015) describe the wider problem in tendons, which is that the amount of structural disorganization seen on a scan does not map neatly onto how a person feels, in much the same way that it does not in osteoarthritis or in disc degeneration. So a scan can show the tendon. Deciding that the tendon is the problem is done by examining the knee.
Do you need an MRI for patellar tendonitis?
Most people do not, because the result would not change the plan. The diagnosis rests on two features, pain at the bottom tip of the kneecap and pain that rises with the demand on the thigh muscles, and the treatment is a staged loading program either way (Malliaras and colleagues, 2015). A scan earns its place in three situations: the diagnosis is genuinely unclear and another cause of front of knee pain needs excluding, a tear is suspected, or an operation is on the table. The same authors note that imaging is useful for including or excluding alternative diagnoses, which is a narrower job than confirming this one. If you want a scan for reassurance, it is worth knowing in advance that an abnormal looking tendon is a common finding and often reads as more alarming than it is.
How do you test for patellar tendonitis?
By pressing the sore spot and then loading the tendon. Malliaras and colleagues (2015) name the two hallmark features: pain localized to the inferior pole of the patella, which is the bottom tip of the kneecap, and load related pain that increases with the demand on the knee extensors, particularly in activities that store and release energy in the tendon, such as jumping and landing. The load test commonly used is a single leg decline squat, performed with an upright torso to 90 degrees of knee bend or to the maximum angle pain allows. A clinician does that in context, alongside the history and the rest of the examination, and it is an assessment rather than something to score at home.
Can a scan tell how long it will take to get better?
No, and this is the question scans are worst at. Symptoms in this tendon often improve without a matching change on ultrasound or MRI, which is the reason serial imaging through treatment is not recommended (Malliaras and colleagues, 2015). What does track your progress is duller and more useful: a repeatable load test done at the same time of day, the next morning response, and a questionnaire score. Our guide to outcome measures in physical therapy explains how those are used. One finding runs the other way and is easy to misread. In people with no pain at the time, an abnormal looking tendon on ultrasound was associated with a higher risk of developing symptoms later (McAuliffe and colleagues, 2016), but that is a screening observation in mostly sporting populations, not a prognosis for a knee that already hurts.
References
- Malliaras P, Cook J, Purdam C, Rio E. Patellar Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations. Journal of Orthopaedic and Sports Physical Therapy. 2015;45(11):887-898. https://doi.org/10.2519/jospt.2015.5987
- Docking SI, Ooi CC, Connell D. Tendinopathy: Is Imaging Telling Us the Entire Story? Journal of Orthopaedic and Sports Physical Therapy. 2015;45(11):842-852. https://doi.org/10.2519/jospt.2015.5880
- McAuliffe S, McCreesh K, Culloty F, Purtill H, O'Sullivan K. Can ultrasound imaging predict the development of Achilles and patellar tendinopathy? A systematic review and meta-analysis. British Journal of Sports Medicine. 2016;50(24):1516-1523. https://doi.org/10.1136/bjsports-2016-096288
- American Academy of Orthopaedic Surgeons. Patellar Tendon Tear. OrthoInfo. https://www.orthoinfo.org/en/diseases--conditions/patellar-tendon-tear/
- NHS. Knee pain. Page last reviewed 21 December 2023. https://www.nhs.uk/symptoms/knee-pain/
Written and checked by the PocketPhysio editorial team. Last updated 2026-10-21.
This page is general education, not a diagnosis or a personal treatment plan. See a physiotherapist or doctor for advice about your own situation.