A bruise on the knee may appear black, blue, or purple on lighter skin, or dark purple or brown on darker skin. Bruises may change color as they heal, turning yellow or green. A knee bruise may also trigger symptoms such as: pain and tenderness.

Treatment for knee osteoarthritis may include lifestyle changes like exercising, doing stress-relieving activities, and working with a physical therapist. It may also include medical treatments like medication, knee injections, or surgery.

Over-the-counter medications — such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) — may help ease knee pain. Some people find relief by rubbing the affected knee with creams containing a numbing agent, such as lidocaine, or capsaicin, the substance that makes chili peppers hot.