Your knee is the largest joint in your body. The kneecap, or patella, is the bone that covers your knee. It helps give the joint strength and structure, which allows your legs to bend and turn safely.
Because your knee has many working parts and carries a heavy load, it’s prone to problems.
If you have any of these issues with your kneecap, see your doctor so you can figure out the right treatment. Some of them can get better with physical therapy, while others may need surgery.
Your kneecap can get knocked out of place, or dislocated, when your leg is planted and you suddenly change direction. It can also happen when something hits your leg and forces it in another direction.
Signs that you’ve dislocated your kneecap include:
Patellar Instability and Dislocation
Your knee also might dislocate without an injury because there’s a problem with the structure. That’s called patellar instability. It’s most common in children and teens, though it can happen in adults, too. Structural issues might include:
- The kneecap rests in a notch at the end of the thigh bone called the trochlear groove. If that notch is very shallow or uneven, it’s easier for the patella to slide out of place.
- Your ligaments are looser, making your joints more flexible and likely to dislocate. This is especially true of girls.
- Cerebral palsy and Down syndrome can cause muscle weakness and balance problems that affect kneecaps.
- Some children are born with unstable kneecaps.
No matter the cause, symptoms of kneecap dislocation are the same.
If it’s only part of the way out, you’ll get a brace to keep you from moving your knee. Within 1 or 2 weeks, you’ll start physical therapy to strengthen your thigh muscles. You can expect about 1 to 3 months for recovery.
If it pops totally out, your doctor will first gently push it back into place. In some cases, you might also need surgery to repair damage to your thigh bone or the cartilage behind your knee.
If it keeps happening, you may need surgery to tighten the ligaments and help keep your kneecap on track.
This happens when your kneecap slides a little out of place but doesn’t dislocate entirely. It’s also a type of patellar instability.
Symptoms that your kneecap has subluxated include:
- Pain in the front of your knee
- A feeling that your kneecap is loose
- Your knee suddenly buckles
This is a serious injury where you break your kneecap, usually:
- In a fall, landing directly on your knee
- A direct hit to your knee, like slamming it against the dashboard in a car accident
If you break your kneecap, your symptoms might include:
- You can’t walk
- You can’t straighten your knee or keep it straight when you raise your leg
If the broken pieces are still lined up, you’ll get an immobilizer brace to hold everything in place as you heal. Sometimes, you can still put weight on your knee. In other cases, you might be off your feet for 6 to 8 weeks.
For a more serious fracture, you typically need surgery. Your doctor may use screws, pins, or wires to hold the bone pieces in place.
In either case, you’ll need physical therapy to work through stiffness, get your range of motion back, and build leg strength.
Patellar Tendon Tear
The patellar tendon starts in your thigh muscles, wraps around your kneecap, and connects to the top of your shinbone. If you completely tear the tendon above the kneecap (the quadriceps tendon) or below it (the patellar tendon), you won’t be able to straighten your knee.
- Small tears. For small tears, you typically wear a brace and have crutches for 3 to 6 weeks. The brace keeps your knee straight while your tendon heals. You’ll also get physical therapy to help with leg strength and range of motion.
- Large tears. Most people need surgery for a large patellar tendon tear. It usually takes 6 to 8 weeks for the tendon to heal after surgery, but it can take up to a year for a full recovery.
Also called patellar tendinopathy or jumper’s knee, this is an injury to the patellar tendon. It’s common with people who play sports like basketball and volleyball.
You typically start treatment with basic self-care, like rest and over-the-counter pain relievers.
From there, you might need to see a physical therapist who can:
- Reduce pain and swelling with ice massage, ultrasound, or iontophoresis, which uses a small amount of electricity to push cortisone, a drug, into your body through your skin
- Give you stretches and strengthening exercises for your thigh muscles
- Show you how to use a patellar tendon strap to relieve pressure on the tendon
If these treatments don’t work, your doctor may talk to you about getting a cortisone injection to help with pain and swelling. The drawback with this treatment is that it can also weaken the tendon and make a tear more likely. Another option is to get an injection of platelet-rich plasma. But this has not been proven to work better than physical therapy or other treatments.
It’s rare, but if nothing else works, you might need surgery to remove damaged tissue and repair the tendon.
Patellofemoral Pain Syndrome
This catch-all term describes pain in the front of the knee and around the kneecap. Sometimes it’s called “runner’s knee” or a “tracking” problem. Typically caused by overuse, patellofemoral pain syndrome can lead to pain, stiffness, or a buckling feeling in the knee and lower thighbone. It’s common in athletes, especially females and young adults.
If you have this condition, you might hurt when you:
- Go up or down stairs
- Kneel or squat
- Sit with your knees bent for a long time, such as during a movie or plane ride
You might also hear popping or crackling in your knees when you climb stairs or get up after you’ve been sitting a long time.
Patellofemoral pain syndrome can happen because of strain on your knees, like climbing too many steps. The pain might start because you’ve suddenly started to exercise more, such as going from working out 3 days a week to 6. Or maybe you’ve made your workouts more intense.
Other things that might bring on patellofemoral pain syndrome:
Often, it gets better with over-the-counter pain relievers and the “RICE” method:
- Rest. Avoid activities that trigger pain, and try not to put any weight on your knee.
- Ice. Wrap an ice pack in a towel and apply it 20 minutes at a time, several times a day.
- Compress. Use a stretchy bandage that has a hole for your kneecap. You want it to feel snug but not tight.
- Elevate. Keep your knee higher than your heart as much as possible.
Your doctor may suggest physical therapy to:
- Improve strength and range of motion in your thigh, hip, abs, and lower back
- Show you how to tape your knee or use a brace to reduce pain
- Teach you how to correct your form if your knee moves in when you squat
Rarely, you might need surgery to remove damaged cartilage, loosen tendons, or realign the patellar tendon and the top of the shinbone.
Patellar Tracking Disorder
Patellofemoral pain syndrome also may come from an alignment problem in how your knee works. When you have misalignment, or a patellar tracking issue, your kneecap can push to one side of the trochlear groove when you bend your knee. That irritates the area, causing pain.
Tracking problems could come from overall alignment issues between your leg and hip. Weak thigh muscles can also be part of the problem.
Damage to the cartilage behind the kneecap is called chondromalacia. You may feel a dull pain around or under your kneecap that gets worse when you go down stairs.
Again, you’ll start with self-care:
- Avoiding activities that cause pain
- Applying an ice pack wrapped in a towel for 15 to 20 minutes, four times a day for several days
- Over-the-counter pain meds
You might also see a physical therapist for help with:
- Changes in how you exercise -- you’ll need to avoid high-impact activities as well as kneeling and squatting
- Choosing the best footwear for your activities
- Safe exercises to stretch and strengthen your thigh and hamstring
- Shoe inserts, if you need them
- Tape, brace, or a sleeve to keep your kneecap aligned
If these treatments don’t work, you may need surgery to remove damaged cartilage and correct kneecap alignment.
A bursa is a small, fluid-filled sac. It eases friction between bones and soft tissue, like tendons. With prepatellar bursitis, the bursa in the front of your knee gets irritated and swells with extra fluid. That puts pressure on your knee that leads to pain.
If it happens due to an injury, it usually goes away on its own with a little self-care:
- Avoid activities that trigger pain
- Wrap an ice pack in a towel and apply it for 20 minutes, three to four times a day
- Keep your knee above your heart as much as possible
- Take over-the-counter pain relievers
If these treatments don’t work, your doctor may:
- Take fluid out of the bursa using a needle
- Give you a cortisone injection to help with pain and swelling
If the bursa is infected, you’ll also need antibiotics. If they don’t help, you may need surgery to get out the extra fluid.
If you have repeated problems with the bursa, your doctor may suggest you have surgery to remove it.
You can’t avoid every possible injury to your kneecap. But you can take some simple steps to help keep your knees healthy:
- Wear the right shoes for your activity.
- Warm up before you work out.
- Do exercises to keep your thigh muscles (quadriceps and hamstrings) strong and flexible.
- If you’re going to make your workouts longer or more intense, do it gradually.
- Cut back on anything that causes knee pain.
- Stay at a healthy weight -- it lowers stress on your knees.