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Bones, Muscles & Joints

Sinding-Larsen-Johansson Syndrome

Lea este articulo en EspanolTony was a star sprinter on the track and field team at his middle school, but in high school it seemed like his friends matured earlier and surpassed him. During junior year, Tony grew about 4 inches. He started training extra hard to make up the ground he felt he’d lost. After a few weeks of intense training, however, Tony’s knee started to hurt so much that he had to stop practicing.

When the pain didn’t go away after a couple of days, Tony went to see a doctor. The doctor asked questions about Tony’s activities and seemed particularly interested in his recent growth spurt. The doctor told Tony that he most likely had a condition called Sinding-Larsen-Johansson syndrome.

What Is Sinding-Larsen-Johansson Syndrome?

Sinding-Larsen-Johansson (SLJ) syndrome is a painful knee condition that most commonly affects teens during periods of rapid growth.


Your kneecap, or patella, is connected to your shinbone (tibia) by the patellar tendon. When we’re still growing, the tendon attaches to a growth plate at the bottom of the kneecap. Repetitive stress on the patellar tendon can cause this growth plate to become irritated and inflamed.

Who Gets It?

SLJ mostly happens to people between the ages of 10 and 15 because that’s when most of us have growth spurts. SLJ is more common in teens who play sports that require a lot of running or jumping, because these activities put excess or repetitive strain on the knee.

What Are the Symptoms of SLJ?

Here are some signs that knee pain may be SLJ:

  • pain at the front of the knee, near the bottom of the kneecap (this is the main symptom of SLJ)
  • swelling and tenderness around the kneecap
  • pain that increases with exercise or activities like running, climbing stairs, or jumping
  • pain that becomes more severe when kneeling or squatting
  • a swollen or bony bump at the bottom of the kneecap

How Is SLJ Diagnosed?

If you see a doctor for knee problems, he or she will ask questions about how much pain you’re having and if you do any sports or other activities. Your doctor will probably also look through your medical records to see if you’ve had a recent growth spurt. The doctor will also examine your knee for swelling and tenderness.

In very rare cases, doctors will ask patients to get an X-ray or magnetic resonance imaging (MRI) scan to rule out other possible problems, like a fracture or infection.

What Causes SLJ Syndrome?

The large muscle group at the front of the upper leg is called the quadriceps. Every time you straighten your leg, your quadriceps pulls on your patellar tendon to bring your lower leg forward. This puts stress on the growth plate at the bottom of your kneecap.

When we go through a period of rapid growth, our bones and muscles don’t always grow at the same rate. As the bones grow longer, muscles and tendons can become stretched and tight. This adds to the strain on the patellar tendon and on the growth plate it is attached to. Repetitive or excess stress in this area can cause the growth plate to become irritated and painful.

Things that can contribute to developing SLJ include:

  • Sports that involve a lot of running and jumping. Track and field is the most obvious example, but sports like soccer, gymnastics, basketball, lacrosse, and field hockey also can put stress on the kneecap.
  • Increased or incorrect training or exercise. Suddenly adding miles to a jogging regimen or going from a period of inactivity to daily sports practices can add to the pressure on the knees. Similarly, improper form while training, an unusual way of running, or shoes that don’t support the feet enough can increase a person’s chances of developing SLJ.
  • Weak or tight quadriceps muscles. Muscles that are stronger and more flexible will work more efficiently, reducing the strain on the kneecap and patellar tendon.
  • Activities that place more stress on the knees. Activities that are tough on the knees include things like walking up and down stairs, lifting heavy objects, and squatting. If you already have pain in your knee, these things can make it worse.

How Can You Prevent SLJ Syndrome?

The most important thing you can do to prevent getting SLJ is to stop doing an activity that causes pain in your knee at the first signs of irritation. Then, try to limit your activity until the pain goes away.

It’s vital to warm up well and stretch before exercising or playing sports. Take a light jog around the track or field for a few minutes to get your blood circulating, then do some dynamic stretching.

If your quadriceps muscles are tight, you may want to do some static stretches for this area ― ask your athletic trainer or a sports medicine expert what’s best for you. Doing a few static stretches when you’re finished with an activity also helps prevent tight muscles. Hold each stretch for at least 30 seconds.

How Should You Treat SLJ Syndrome?

The first ― and most important ― thing to do is to stop any activity that causes irritation in your knee. Don’t resume your activities until you can run, jump, and stretch without pain or a doctor has cleared you to play again.

SLJ can be tricky because it might not completely resolve until your bones have fully matured and your growth plates are completely closed. In the meantime, knee pain may come and go during activity.

Other things you can do include:

  • Use the RICE formula:

    • Rest. Limit your activities as much as possible and keep your weight off your knee. Walking should be kept to a minimum.
    • Ice. Apply ice or a cold compress to the affected area for 15-20 minutes every few hours. Do this for 2 to 3 days or until the pain goes away.
    • Compress. Give your knee added support by using a brace, band, or strap.
    • Elevate. Try to keep your knee higher than your heart to help keep the swelling down.
  • Take anti-inflammatory or painkilling medications. Painkillers like ibuprofen and acetaminophen can help relieve pain and reduce swelling.
  • Begin a stretching and strengthening program. When the pain and tenderness in your knee are gone, talk to your doctor or sports injury professional about a physical rehabilitation program to strengthen the muscles of your leg and increase their flexibility and range of motion.

The good news about SLJ is there’s less chance of it happening as you grow and develop. So listen to your body and don’t overdo things.

It’s easy to get impatient when sidelined by an injury, but taking care of your body now helps you build the strength needed for future games and activities.

Reviewed by: Alfred Atanda Jr., MD
Date reviewed: November 2014