A bruised knee typically causes moderate to severe pain that worsens when you bend, straighten, or put weight on the joint. The pain can be sharp on contact and settle into a deep, stiff ache at rest. Depending on what’s bruised (skin, muscle, or bone), the sensation ranges from surface-level tenderness to a deep throbbing that makes even simple movements like standing up from a chair feel difficult.
Where and How It Hurts
The pain from a bruised knee doesn’t always stay in one predictable spot. It might center around the kneecap, settle into the hollow behind the knee, or radiate along the sides of the joint. Sometimes you genuinely can’t pinpoint where the pain is coming from, which can be unsettling.
When you touch the area directly, it’s tender and sore. Pressing on the bruise recreates or intensifies the pain. Beyond tenderness, you may notice warmth radiating from the skin over the knee, along with visible swelling that makes the joint look puffy compared to your other leg. The knee often feels stiff, as though it doesn’t want to bend or straighten all the way. Some people describe a sensation of something rubbing inside the joint, though they can usually still move it.
How It Affects Everyday Movement
A bruised knee makes weight-bearing activities noticeably harder. Walking, climbing stairs, getting out of a car, or rising from a chair all involve bending or straightening the knee, and each of those motions can flare the pain. The muscles around the knee may feel weak or reluctant to engage, not because they’re damaged but because swelling and pain signal your body to guard the area. In more severe cases, the knee can feel wobbly or unstable when you stand, like it might give out under you.
This instability is usually temporary and related to swelling rather than structural damage, but it’s one of the more alarming sensations. If the bruise is bad enough, putting full weight on the leg may feel nearly impossible for the first day or two.
What It Looks Like as It Heals
The visual progression of a knee bruise follows a predictable color timeline driven by your body breaking down trapped blood beneath the skin. Right after impact, the area typically looks red. Within a day or two, it shifts to purple or dark blue. By days five through ten, the bruise fades to green or yellow. Around days ten to fourteen, it turns a yellowy-brown before disappearing entirely, usually within about two weeks for a standard soft tissue bruise.
Swelling tends to peak in the first 24 to 48 hours and gradually decreases alongside the color changes. The area may also feel slightly lumpy or firm to the touch early on as blood pools in the tissue.
Soft Tissue Bruise vs. Bone Bruise
Not all knee bruises feel the same, and the key difference is depth. A soft tissue bruise (the common kind from bumping your knee on a table or taking a fall) affects the skin, fat, and muscle layers. It’s painful and colorful but generally resolves in about two weeks.
A bone bruise goes deeper. It happens when the impact is forceful enough to damage the bone itself without actually breaking it. The pain from a bone bruise tends to feel more intense and persistent, with a deep ache that doesn’t fully let up even at rest. The biggest practical difference is healing time: most bone bruises last a few weeks, but more severe ones can take months or longer to fully resolve. They also carry a higher risk of progressing to a fracture if the knee takes another hit before healing is complete. Bone bruises don’t always show visible discoloration on the skin surface, which means you can have significant pain with little to see on the outside.
Why It Feels Worse at Night
Many people notice their bruised knee throbs more at bedtime. Part of this is simply that daytime distractions are gone, making you more aware of the sensation. But there’s a physical component too. When you stop moving, the joint stiffens. Fluid that accumulated during the day settles, and the lack of muscle activity means less circulation to the area.
Placing a pillow (or two) between your knees when sleeping on your side, or under your knees when on your back, takes pressure off the joint and keeps it in a more neutral position. A cold gel pack wrapped in a towel can also help reduce the throbbing. Smooth, low-friction sheets and pajamas let you shift positions during the night without tugging on the sore leg, which helps prevent the deep morning stiffness that makes the first steps out of bed feel especially rough.
Signs Something More Serious Is Going On
A straightforward bruise hurts, but it follows a steady path toward improvement. Certain symptoms suggest the injury might be more than a bruise. Sudden, significant swelling that develops within minutes of the injury can indicate bleeding inside the joint. A “popping” sound at the moment of impact raises concern for a ligament tear. If the knee looks visibly deformed, won’t bear any weight at all, or feels like it locks or catches during movement, the injury likely involves structures beyond the surface tissue.
A knee that stays red, warm, badly swollen, and very painful several days after the injury, rather than gradually improving, also warrants medical evaluation. These signs overlap with infection and inflammatory conditions that need different treatment than simple rest and ice.