Bruised knee

The typical symptoms of bruising to the knee are:

• Moderate to severe pain in the knee, especially when you put weight on it, or bend or extend it. The pain might be around the kneecap (patella) at the front of the knee, in the hollow of the knee or on the sides. Sometimes you can’t actually tell where the pain is coming from.
• Visible bruising on the skin caused by internal bleeding
• Slight or moderate swelling, which takes a couple of hours to develop
• Not being able to stretch or bend the knee properly because of the pain. Sometimes it also feels like something inside the joint is rubbing but usually you can still move the joint.

Typically, bruising to the knee doesn’t involve damage to the skin but there is sometimes a scrape or cut. If the skin is damaged and there’s dirt in the wound, it’s important to check whether your tetanus vaccination is up to date.

The following symptoms may be a sign that your knee injury is more complicated:

• Extreme pain, making it almost or completely impossible to put strain on the knee.
• Symptoms that get worse, come back or don’t go away even after several weeks.
• Rapid swelling. This can be a sign of an injury to the cartilage, bones, ligaments, meniscus or muscles. Sometimes swelling can occur inside the joint capsule too. You can’t see this from the outside but the pain can be intense and your knee might feel stiff.
• Redness, swelling and an unusually warm sensation. These symptoms can point to an inflammation.
• Not being able to move your knee, or an immediate feeling that something’s become dislocated or torn.
• A wobbly or unstable sensation when you put weight on your knee – like when you’re standing or walking.

If your symptoms suggest a more complicated injury, it’s important to get a doctor to take a look.

Children often have trouble saying what’s hurting and how much. Parents who are unsure whether the injury might be more serious can ask a doctor. This is especially important if you notice changes in the child’s behavior that might be a sign of something more complicated. Things like them being much less active than usual or changing the way they walk so it doesn’t hurt.

Bruising to the knee is usually caused by a direct, blunt impact on the knee joint, like a blow or a fall. This is common in everyday life. It can happen while playing sports, doing housework or at the playground, but it can also be caused by punching or kicking.

The impact makes soft tissue press against the bones or the joint capsule in the knee. This causes tiny blood or lymph vessels to tear, which can lead to bleeding and swelling.

It usually takes just a few days or weeks for a simple bruise to the knee to heal.

The amount of time this will take depends on things like

• which parts of the knee are affected. For instance, muscles heal more quickly than joint capsules or the membrane that covers the bones (periosteum);
• how strong the force of the impact was and how severely the tissue was damaged;
• how quickly the knee was treated (by cooling it or putting it up, for instance); and
• whether you already had knee problems – like osteoarthritis or inflammation, for example.

Only a doctor can say whether the bruising is more complicated than it appears. People usually go to see their family doctor or pediatrician first. The doctor will ask you to describe the symptoms in detail and how the injury occurred. Then they can decide whether it’s likely to be a damaged meniscus or torn ligament.

They will also look at the knee and feel it to see whether it’s swollen, warm or painful, and if there are any visible signs of injury, like external bruising. Another test is to get you to bend your knee and put strain on it to check how much you can move it. If you can’t walk or limp roughly four steps without assistance, the injury is probably serious.

It is common to be referred to an orthopedic practice or clinic if the symptoms suggest a more complicated injury. They will examine your knee in more detail and do an x-ray if necessary. This is also the usual approach if the symptoms last several weeks or get worse. When that happens, the doctor might recommend an ultrasound, MRI or CT scan as well.

When children who hurt their knee playing sports or games need a diagnosis, they usually go to their pediatrician. If the doctor thinks the injury might be more complicated (a fracture or torn ligament, say), the child is usually referred to an orthopedist or surgeon specialized in treating children. They can do an x-ray or MRI scan.

If the bruising to the knee is straightforward, there’s typically no need for medical treatment. But there are lots of things you can do to help your knee heal.

The acronym P.R.I.C.E. can be used to remember an approach for treating any muscle or joint injury, including bruising to the knee. P.R.I.C.E. stands for:

• P as in protection: This means protecting the affected area from pressure or bumps. Walking aids are sometimes a good idea too, to help relieve the pressure on the leg.
• R as in rest: Make sure to rest the knee for a little while.
• I as in ice: One of the first things you can do is cool the knee for five to ten minutes. You can do this several times per day. It is important to wrap the ice or cool pack in a thin towel or cloth first though. Never put it on your knee with nothing around it – it could harm the skin otherwise.
• C as in compression: An elastic compression bandage that’s not too tight can prevent the injured area from becoming more swollen. It should be wrapped around the leg from the ankle upward. Putting a tightly wrapped bandage or a special cuff around the joint, or taping it, will also automatically keep it from moving too much.
• E as in elevate: It can be helpful to put your leg up (elevate it) several times a day to reduce the swelling.

Your doctor can prescribe ointments or gels to relieve the pain and keep the swelling down. There are lots of non-prescription products available. If you’re looking to get one for your child, it’s best to ask the pharmacist. If you’ve never put a bandage on yourself or your child, you can ask the team at your practice to show you how to do it properly so it does its job without being too tight. If the knee needs to be rested for quite a while, you might have to take precautions to prevent thrombosis. If it’s badly bruised and has to be kept completely still (immobilized), you might be given a splint.

Many people like to use herbal ointments or lotions (containing things like arnica) to make a wrap to put on their knee. But there is no scientific proof that this is effective.

If you want to use herbal products for a wrap for a child, it’s best to ask the doctor first. Some products are not suitable for children.

When people are ill, have a sick child, or need medical advice, they usually go to see their doctor first. In our topic "Health care in Germany" you can read about how to find the right doctor – and our list of questions can help you to prepare for your appointment.