Patellar tendonitis causes a focused, aching pain just below your kneecap, right where the tendon connects the kneecap to the shinbone. In early stages, you’ll only notice it during or right after physical activity. As it progresses, the pain can creep into everyday movements like climbing stairs, standing up from a chair, or even sitting still.
Where the Pain Shows Up
The pain is localized to a very specific spot: the bottom edge of your kneecap and the top portion of the patellar tendon, which runs vertically from kneecap to shinbone. If you press on that area with your knee straight, it will feel tender. Bending your knee actually reduces the tenderness, which is one way clinicians confirm the diagnosis. The proximal third of the tendon (the part closest to the kneecap) is typically where the problem lives, and that section often becomes noticeably thicker than normal.
Most people describe the pain as a deep ache that sharpens with load. It’s not a diffuse knee soreness. You can usually point to it with one finger.
How It Feels at Different Stages
Patellar tendonitis doesn’t arrive all at once. It follows a fairly predictable pattern that clinicians break into three stages based on when the pain appears relative to activity.
In stage 1, pain only shows up after activity. You finish a run or a basketball game and notice a dull ache below your kneecap. It fades with rest. At this point, many people dismiss it as normal soreness.
In stage 2, you feel pain both during and after activity. The tendon hurts when you start moving, may ease up slightly as you warm into it, then flares again afterward. This is the stage where most people start paying attention.
In stage 3, the pain is present during activity and starts to limit your performance. Jumping feels unreliable. You may begin avoiding movements that load the knee. At this point, some people also experience pain during routine daily tasks or even at rest.
Morning Stiffness
A hallmark of patellar tendonitis is stiffness in the knee first thing in the morning. The tendon feels tight and reluctant to bend, but this usually loosens up after a few minutes of walking around. Morning stiffness is often the first symptom to improve as the condition heals, which can be a useful way to gauge whether your recovery is on track. If you notice the stiffness lasting longer than usual after exercise or rehab, that’s a sign you’ve done too much.
What Makes It Worse
Anything that loads the patellar tendon heavily will aggravate the pain. The biggest triggers are jumping and landing, which is why the condition is sometimes called “jumper’s knee.” Forces on the patellar tendon during jumping can reach extreme levels. Olympic weightlifters, for example, generate forces up to 17 times their body weight through this tendon during deep squats.
You don’t have to be an elite athlete to feel it, though. Common aggravating movements include:
- Jumping or hopping, even casually
- Running, especially with sudden acceleration or deceleration
- Climbing or descending stairs
- Rising from a chair or getting out of a car
- Deep squatting or lunging
- Prolonged sitting with knees bent, which can produce a stiff, achy feeling when you finally stand
The pattern is consistent: the more you ask the tendon to absorb or transmit force through a bent knee, the more it protests.
How It Changes Over Time
If the load on the tendon is reduced early, the inflammation can settle and the tendon returns to normal. But when high, repetitive loading continues, the injury shifts from an inflammatory problem to a degenerative one. The tendon’s internal structure starts to break down at a cellular level, and the pain becomes more persistent and harder to resolve.
In mild cases, the pain is neatly tied to sport or exercise. In moderate cases, it starts bleeding into the beginning of workouts and lingers after. In severe cases, people report pain during ordinary activities, walking on flat ground, or sometimes just sitting with the knee bent. At this point the tendon may feel sore to the touch throughout the day, not just after exertion.
What It Doesn’t Feel Like
Patellar tendonitis doesn’t cause sharp, locking, or catching sensations inside the knee joint. If your knee feels like it’s giving way or something is shifting inside, that points to a different problem, such as a meniscus tear or ligament issue. Patellar tendonitis also doesn’t cause significant visible swelling in most cases. The tendon may thicken over time, but you won’t typically see the puffy, fluid-filled swelling that comes with a sprained joint. The pain stays localized below the kneecap rather than wrapping around the sides or back of the knee.
If pressing firmly on the bottom edge of your kneecap with your leg straight reproduces your pain, and that tenderness drops noticeably when you bend your knee, that’s a strong signal you’re dealing with patellar tendonitis rather than something inside the joint itself.