Part of Patellar tendinopathy
Can patellar tendonitis lead to a tear if you keep training?
Warning signs, and when to get help
Can patellar tendonitis lead to a tear?
Yes in one narrow sense, no in the sense you are probably asking about, and the gap between those two is where most of the fear on this subject lives.
OrthoInfo, the patient library of the American Academy of Orthopaedic Surgeons, states that patellar tendinitis weakens the tendon and may also cause small tears. It also lists the condition among the things that leave a tendon weak enough to rupture. So the answer is not simply no.
The thing people picture when they ask, though, is the tendon letting go in the middle of a game. That is a rupture, and OrthoInfo says plainly that it takes a very strong force, with the usual mechanism being the knee bent and the foot planted, such as landing from a jump or jumping up. A tendon that has hurt for six months is not sitting on a fuse.
What we cannot give you is a number. There is no figure we can trace for how often patellar tendon pain is followed by a rupture, and a number for a different tendon is not a number for this one. Achilles tendon rupture is where the figures that do exist for that tendon live, and they belong to it rather than to the knee.
The two things the word tear means
Separating these two is most of the answer, because one word is doing duty for two completely different things.
The first kind is microscopic and ongoing. A tendon under more load than it can handle changes internally, and OrthoInfo describes patellar tendinitis both weakening the tendon and producing small tears. That is the condition itself rather than an accident, and it is what the staged loading on the patellar tendinopathy program is built to turn around.
The second kind is an event with a time stamp. A partial tear, in OrthoInfo's words, does not completely disrupt the tendon. A complete tear separates the tendon from the kneecap, and without that attachment you cannot straighten the knee.
One detail explains why the two are related without being the same thing. OrthoInfo says the patellar tendon often tears where it attaches to the kneecap, sometimes taking a piece of bone with it, but that when a tear is caused by a medical condition such as tendinitis, it usually happens in the middle of the tendon instead. So the tissue that has been sore for months is the tissue that gives way, when giving way happens at all.
What it takes to rupture a patellar tendon
A specific load, in a specific position, and more of it than training normally supplies.
OrthoInfo's description of the mechanism is the knee bent with the foot planted, which is the position of a landing, a jump take-off, or a stumble that catches you with your weight on a bent knee. It also lists a direct blow and a fall as causes. Strength work, running and the daily business of a sore knee are not in that list.
None of that is permission to ignore the pain, for reasons that have nothing to do with rupture. It does mean the mental image most people arrive with, of a tendon that is one session away from snapping, is not what the source says.
What makes a tendon more likely to tear
Here is the uncomfortable half, and most of it is not training volume.
OrthoInfo lists the things that weaken a patellar tendon. Patellar tendinitis is one. Corticosteroid injections are another. It also names diseases that interfere with the tendon's blood supply, including chronic kidney failure, high cholesterol, inflammatory diseases such as rheumatoid arthritis and lupus, diabetes mellitus, infection and metabolic disease.
Previous surgery around the tendon is on the list too, and OrthoInfo names a total knee replacement and an ACL reconstruction as examples that may raise the risk. If either applies to you, the total knee replacement rehab and ACL reconstruction rehab pages set out what those recoveries involve, and your own surgical team's advice comes ahead of anything here.
One more route is a medicine rather than a sport, and it has its own line on the warning list at the foot of this page: tendon pain or swelling that began during or after a course of a particular class of antibiotic. Read that line rather than this summary of it, because it says what to do.
So the reader at real risk is usually not the fit volleyball player with six months of knee pain. It is more often someone with one of those conditions, someone who has had injections around the tendon, or someone who has had surgery there before.
Why steroid injections are avoided around this tendon
This is the clearest practical consequence of everything above.
OrthoInfo states that corticosteroid injections used to treat patellar tendinitis have been linked with increased tendon weakness and an increased likelihood of rupture, and that doctors therefore typically avoid giving them in or around the patellar tendon. That is a statement about this tendon from a surgical body, not a general suspicion of injections.
The treatment evidence points the same way without needing the safety argument. Challoumas and colleagues (2021) reviewed 37 randomized trials, named eccentric loading the first-line treatment, recommended against shockwave therapy and against concentric exercise on its own, and described most of the evidence base as low or very low certainty. If an injection is being discussed for your knee, that is a conversation with the doctor assessing it, and this page is not advice either way.
What training through the pain actually costs
Not a rupture, in all likelihood. Time, and a lot of it.
The clearest picture of that cost comes from a trial by Breda and colleagues (2021). In it, 76 people with patellar tendinopathy spent 24 weeks on one of two programs, staged tendon loading or eccentric exercise. On the tendon questionnaire the staged group gained 28 points and the other 18, a 9 point difference that was statistically significant. Then comes the figure this question turns on. At the end of those 24 weeks, 43 percent of the staged group and 27 percent of the eccentric group were back in their sport at the level they had played before, and that gap was not statistically significant.
Read that again as a cost. Even with the better of two real programs, most people were not back at their old level after six months. That is the price of a tendon that has been left to get worse, and it arrives quietly rather than as a dramatic injury. If that is already where you are, why your patellar tendonitis is not healing is the next page to read.
The signs of a tear, and the first hour
Worth reading once now, because this is not a decision to make while it is happening.
OrthoInfo's list for a patellar tendon tear: a tearing or popping sensation at the moment, bruising, tenderness, cramping, an indentation at the bottom of the kneecap where the tendon tore, the kneecap moving up into the thigh because it is no longer anchored to the shinbone, and difficulty walking as the knee buckles or gives way. With a complete tear, straightening the knee is not possible.
What to do is simple and it is in the first warning line at the foot of this page. Stop, keep your weight off the leg, and go to an emergency department straight away, even if you can walk. Do not drive yourself.
The reason the timing is in the line is that OrthoInfo states people who need surgery do better when the repair is performed soon after the injury, and that early repair may prevent the tendon scarring and tightening into a shortened position. It also says tendons often shorten once more than a month has passed since the injury, and that a tendon which has shortened too far is hard to reattach to the kneecap, so the surgeon may have to lengthen it with a tissue graft, sometimes donated tissue. That is the practical cost of waiting on this particular injury. A straightforward reattachment turns into a larger operation, and the delay is rarely a decision anyone made on purpose.
Two things fool people here. You can often still walk, because other muscles will move the leg, and a limp is not evidence that the tendon is intact. And a knee that someone else can straighten for you, while you cannot hold it straight against gravity yourself, is the sign that matters most. A knee that gives way and a swollen knee cover the two symptoms that most often arrive with it.
After a patellar tendon repair
If you are reading this having already had the operation, your surgeon's protocol is the one to follow, and where it differs from anything below, it wins. Protocols vary with the tear, the repair and the surgeon.
What OrthoInfo describes as the general shape of it is useful for setting expectations. One condition runs underneath the whole of it, and it matters more than any of the dates: the weight goes through the leg in the brace or immobilizer, with the knee held straight, using crutches or a walker. Read that as a checklist for every time you stand up, because it is three separate things and not one: the device on, the knee straight inside it, and the crutches or the walker you were given, rather than a hand on the furniture.
Weight bearing starts at toe touch, which OrthoInfo describes as lightly touching the toe to the floor and putting down just the weight of the leg. It moves to around half your body weight by 2 to 4 weeks and reaches full weight somewhere around 4 to 6 weeks, and where OrthoInfo allows that earlier it says full weight in extension, meaning with the knee straight. That qualifier is doing the protecting. A repaired tendon is pulled on far harder by a bending knee than by a straight one, so permission to take your full weight is not permission to walk about with the brace off and the knee free to bend.
A brace is locked at first, and your doctor or physical therapist unlocks it in stages, never you. Return to sport follows an assessment rather than a date, with the aim that the operated leg is at least 85 to 90 percent as strong as the other one. OrthoInfo puts complete recovery at about 6 months and notes that many people needed 12 months to reach all of their goals.
Motion is where surgeons differ most, and the difference is deliberate rather than untidy. OrthoInfo says most surgeons protect motion early on after this repair, while some prescribe an immediate motion protocol, which it calls a more aggressive approach and not appropriate for all patients. Which of the two you are on was decided for your tear and your repair, and it is not something to pick up from reading about it.
Four things in a repaired knee are reported rather than watched, and each has its own line on the warning list below. A wound that becomes more red, hot, swollen or painful, or starts to leak. A sudden loss of the ability to straighten the knee or lift the leg out straight, particularly after a pop, a tearing feeling or a stumble, which can mean the repair has given way. A newly swollen, warm or tender calf, because the weeks of reduced movement after this operation are exactly the circumstances a blood clot arises in. And the slow version of the second one: a knee that is 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 moment to point to.
That last one is worth separating out, because it does not feel like an injury and so it tends to get mentioned at the next appointment rather than reported. A repair can stretch out gradually instead of letting go all at once, and a widening gap between the straightening someone else can move your knee into and the straightening you can hold yourself is what stretching out looks like from the outside. It is also the reason OrthoInfo lists re-tear and detachment of the tendon from the kneecap among the complications of this operation, along with weakness and loss of motion, which it names as the most common ones. None of that is diagnosed from a page, and all of it is worth a phone call.
One point about rehabilitation after a repair, because the two problems get mixed up. A repaired tendon is not a tendinopathy, and the staged loading program on the parent page is not written for it. Those stages assume a tendon that is intact and irritable, not one that has been stitched back onto the kneecap, and using them instead of your surgical team's plan would mean loading a repair on a schedule nobody wrote for it.
How to keep training without raising the risk
The useful question is not whether to train but which training, and the answer is usually a change of ingredient rather than a stop.
Cut the springy load first, because that is what the tendon reacts to: repeated jumping, landing, bounding and change of direction, particularly at the end of a session when the calf and thigh have stopped absorbing landings. Keep the strength work. Malliaras and colleagues frame this condition as a problem of load tolerance, treated by building what the tendon can take in steps while dealing with whatever keeps overloading it, and resting a tendon until it stops hurting removes the thing that builds tolerance.
Use the morning after as your measure. Malliaras and colleagues set the criterion for tolerating a level of energy-storage work as minimal pain during the exercise, with pain on the load tests back to its usual level within 24 hours. A tendon that is sorer or stiffer the next morning was given too much the day before, and the fix is to drop back one step rather than to stop altogether. The pain monitoring model explains how that kind of rule is used.
How much pain during exercise is acceptable?
A little, and the amount is less interesting than the response. All of this is about a tendon that is intact and irritable. If yours has been repaired, the pain rules that apply to you are your surgical team's, not these.
Most loading programs for this tendon accept mild discomfort during the exercise rather than demanding a pain-free session, and the parent program sets out the stages that use it. Numbers are worth less than consistency here: pick one load test, use it at the same time of day, and compare like with like. Your physio will adjust the dose, the depth and the progression to your tendon and your sport.
Three responses mean the dose was wrong, whatever the number said during the session. Pain that climbs with every repetition instead of staying level. A tendon that is clearly worse the following morning. And pain that stays raised for several days rather than settling.
Can a torn patellar tendon heal on its own?
Only the small ones, and the distinction is structural rather than a matter of toughness.
OrthoInfo says very small, partial tears respond well to nonsurgical treatment: a knee immobilizer or brace that locks in place, generally worn for 3 to 6 weeks, with physical therapy beginning once the initial pain and swelling have settled. Complete tears almost always require surgery, and most people with one need an operation to get knee function back.
The reason is mechanical. A tendon that has separated from the kneecap has nothing holding the two ends together, and the muscle pulls them further apart every time it contracts. Waiting does not bring them back, which is why the warning line sends a suspected complete tear to hospital the same day rather than to an appointment next week.
When to stop and get it checked
Three different timings, and they are easy to mix up.
Stop immediately and go to an emergency department for a pop or tearing feeling at the front of the knee, a dip you can feel, a kneecap that looks as though it has moved, or a knee you suddenly cannot straighten or hold straight. The same goes for a knee that swells up dramatically within a few hours of a twist, a fall or a blow.
Get medical advice the same day for a knee that gives way under you, a knee that is hot, red and swollen or comes with a temperature, and the other same-day lines at the foot of this page.
Book an assessment for tendon pain that has not improved within a few weeks, which is the NHS threshold for knee pain generally. A physio (physical therapist) can confirm where the pain is coming from, set the stage your tendon can handle now, and decide what your sport can have back. Where jumper's knee hurts helps you describe the spot before you go, does patellar tendonitis show up on MRI covers whether a scan is worth asking for, and red flags in physiotherapy explains why the warning list is treated as its own set of questions.
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 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.
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 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 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: your wound becomes more red, hot, swollen or painful, starts to leak or ooze, is still leaking in the second week or has never stopped, has pus coming out of it or its edges start to come apart, or you have a high temperature or feel hot, cold or shivery. Contact your surgical team or get medical advice the same day. Redness can be harder to see on brown or black skin. 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: you suddenly cannot straighten your knee or lift your leg straight when you could before, often after a pop, a tearing feeling or a stumble, or you notice a dip just above or below your kneecap, or you suddenly cannot put weight on the leg, even without a fall. Keep your weight off it and contact your surgical team the same day. If you cannot reach them that day, go to an emergency department. A tendon at the front of the knee may have torn, and a repair works better when it is done soon.
- 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: 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 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: 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: 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
Can patellar tendonitis lead to a tear?
It contributes to the risk without making it inevitable. OrthoInfo states that patellar tendinitis weakens the tendon and may cause small tears, and it lists the condition among the reasons a tendon becomes weak enough to rupture. It also states that tearing the patellar tendon takes a very strong force, so a rupture is an event with a mechanism rather than the natural end point of a sore knee. Anyone offering you a staged model in which untreated tendon pain progresses to a rupture is going beyond what the sources we can check actually say.
What happens if you tear your patellar tendon?
The kneecap loses its anchor to the shinbone, so the muscle that straightens your knee has nothing to pull against. OrthoInfo describes a tearing or popping sensation at the time, an indentation at the bottom of the kneecap where the tendon gave way, the kneecap moving up into the thigh, and a knee that buckles when you try to walk on it. With a complete tear you cannot straighten the knee. Being able to limp is not reassurance: the first warning line on this page sends a suspected tear to an emergency department the same day, even if you can still walk.
Can a patellar tendon tear heal on its own?
It depends entirely on whether the tendon is still in one piece. OrthoInfo says very small, partial tears respond well to nonsurgical treatment, which it describes as a knee immobilizer or brace that locks in place, usually worn for 3 to 6 weeks, followed by physical therapy once the pain and swelling have settled. Complete tears almost always need surgery, because the two ends cannot find each other, and OrthoInfo adds that early repair may stop the tendon scarring and tightening into a shortened position. Which of those you have is a question for a scan and a surgeon, not for a self-test.
Is it safe to keep playing with patellar tendonitis?
Often, with the jumping load reduced and somebody watching the response, and that is a different thing from pushing through. Complete rest is not the treatment for this tendon, and loading it in stages is. What has to come down is the springy work that provoked it: repeated jumping, landing and bounding, especially late in a session when the legs are tired. The call is worth making with a physio rather than alone, because it depends on how irritable the tendon is now and on what your sport asks of it.
References
- American Academy of Orthopaedic Surgeons. Patellar Tendon Tear. OrthoInfo. https://www.orthoinfo.org/en/diseases--conditions/patellar-tendon-tear/
- 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
- 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. British Journal of Sports Medicine. 2021;55(9):501-509. https://doi.org/10.1136/bjsports-2020-103403
- Challoumas D, Pedret C, Biddle M, Ng NYB, Kirwan P, Cooper B, Nicholas P, Wilson S, Clifford C, Millar NL. Management of patellar tendinopathy: a systematic review and network meta-analysis of randomised studies. BMJ Open Sport and Exercise Medicine. 2021;7(4):e001110. https://doi.org/10.1136/bmjsem-2021-001110
- 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.