Sinding-Larsen-Johansson Syndrome

What is Sinding-Larsen-Johansson Syndrome?

Sinding-Larsen-Johansson syndrome (SLJ) is an injury to the growth plate where your kneecap (patella) attaches to your patellar tendon, the tendon that connects your kneecap to your shin bone (tibia). Specifically, SLJ is an injury to the tendon at the spot where the tendon leaves the kneecap (the inferior pole of your patella). It almost always affects children between the ages of 10 and 14 who play sports or are especially active.

The patellar tendon is like a thick rubber band that connects your kneecap to your shin. It holds the bones together and helps them move properly. Sinding-Larsen-Johansson syndrome is caused by repeated tension and pressure on the patellar tendon when kids squeeze their thigh muscles (quadriceps). The overuse that causes SLJ can be caused by any repetitive motion, including:

• Running.
• Jumping.
• Kicking.
• Any activity or sport that makes kids repeatedly exert a lot of force with their legs and knees.

What is the difference between Sinding-Larsen-Johansson syndrome and Osgood-Schlatter disease?

Sinding-Larsen-Johansson syndrome and Osgood-Schlatter disease are very similar and share many causes, symptoms and treatments. In fact, both conditions refer to injured patellar tendons in kids and teens.

The main difference is which part of the patellar tendon is injured. Sinding-Larsen-Johansson syndrome is an injury to the top of the tendon (the proximal end). Osgood-Schlatter disease affects the bottom (the distal end) of the tendon. Young people diagnosed with SLJ injure the tendon right where it leaves the kneecap, while those with Osgood-Schlatter disease damage the tendon at its opposite end, where it exits the shin.

It can be hard to tell the difference between Sinding-Larsen-Johansson syndrome and Osgood-Schlatter disease. However, that similarity can be helpful too. Because they’re both caused by overuse — usually from playing sports — and the most common treatments involve rest and medication to reduce swelling, you’ll be able to relieve your child’s symptoms with the same treatments. Your healthcare provider will explain the specifics of what’s causing you child’s pain, and why it’s SLJ or Osgood-Schlatter.

Who does Sinding-Larsen-Johansson syndrome affect?

Sinding-Larsen-Johansson syndrome affects children and teens between the ages of 10 and 14. Studies have shown that children with cerebral palsy are at increased risk for SLJ.

The age range is so specific because of how kids’ bodies grow and change. Between 10 and 14, the growth plate at the top of their shinbone is very active and vulnerable to injuries. Growth spurts when kids’ bones, muscles and tendons all rapidly change at the same time can put their knees under extra stress too.

Sinding-Larsen-Johansson syndrome in adults

It’s not impossible for Sinding-Larsen-Johansson syndrome to affect adults, but it’s very rare. In fact, if you have similar symptoms to SLJ and are over 15 years old, you likely have another condition like “jumper’s knee.” There are lots of causes of adult knee pain. Talk to your provider if you notice any new discomfort, especially after any intense physical activity.

How common is Sinding-Larsen-Johansson syndrome?

Sinding-Larsen-Johansson syndrome is very common. It’s a frequent cause of knee pain in teens.

How does Sinding-Larsen-Johansson syndrome affect my child’s body?

It can be very painful, but Sinding-Larsen-Johansson syndrome won’t have long-term impacts on your child’s health or ability to resume the activities they love. They’ll need to rest and avoid the activity or sport that caused SLJ for up to a few months, but they should have no lasting impacts of SLJ after their patellar tendon heals.

What are the symptoms of Sinding-Larsen-Johansson syndrome?

The most common symptom of Sinding-Larsen-Johansson syndrome include:

• Sharp pain at the bottom of your child’s knee, right above their shin.
• Swelling.
• Tenderness around their knee.
• Difficulty bending their knee as far they usually can.

What causes Sinding-Larsen-Johansson syndrome?

Sinding-Larsen-Johansson syndrome is caused by overusing the patellar tendon. Like other forms of osteochondritis, it most commonly affects kids and teens who play sports. Each time your child exerts excessive force — running hard, or kicking a soccer ball, for example — they can cause a tiny, unnoticeable amount of damage to their patellar tendon. Over time these “microtraumas” can cause SLJ and its trademark pain and swelling.

How is Sinding-Larsen-Johansson syndrome diagnosed?

Your healthcare provider will perform a physical exam on your child’s knee and shin, and ask them when they first noticed the pain. Your child will also likely undergo some imaging tests to confirm Sinding-Larsen-Johansson syndrome and rule out other conditions and injuries.

What tests will be done to diagnose Sinding-Larsen-Johansson syndrome?

There are a few imaging tests your provider might use to diagnose Sinding-Larsen-Johansson syndrome including:

• X-rays: An X-ray will show if your child’s kneecap, shin or other bones are broken (fractured). Your provider will use an X-ray to look for a stress fracture in the shin, which is common in athletes.
• Magnetic Resonance Imaging (MRI): An MRI will show a complete picture of your child’s knee, including the area around it. This will show if the patellar tendon has thickened as a result of their injury.
• Ultrasound: An ultrasound will show how blood flows through the muscles and connective tissue around your child’s knee.

How is Sinding-Larsen-Johansson syndrome treated?

Rest and stretching the quadriceps are the most common treatment for Sinding-Larsen-Johansson syndrome. Your child should stop playing the sport(s) that caused their injury while their patellar tendon heals.

Most kids need to take between a few weeks to a few months off from sports. How long your child will need to rest depends on how severe their original injury is. Your child might be able to replace their original sport with other, less physically stressful activities (like swimming) while they heal.

In the short term, you can use a combination of icing your child’s knee and taking over-the-counter NSAIDs to relieve pain and reduce inflammation.

Sinding-Larsen-Johansson syndrome surgery

It's extremely unlikely your child will need surgery to treat Sinding-Larsen-Johansson syndrome.

Talk to your provider about your child’s treatment options. Even in more severe cases, your provider will probably recommend other, less invasive treatments like physical therapy before considering surgery for a child or teen’s SLJ.

In some cases, adults diagnosed with SLJ might need knee arthroscopy to repair their patellar tendon.

What medications/treatments are used?

Over-the-counter NSAIDs like aspirin or ibuprofen are typically all you’ll need to reduce the pain caused by Sinding-Larsen-Johansson syndrome. NSAIDs will also reduce inflammation and swelling. Your child can take them as directed to reduce pain, but talk to your provider before starting, stopping or changing any regular use of medications. Your child shouldn’t take NSAIDs for longer than 10 days in a row without your provider’s approval.

Complications/side effects of the treatment

NSAIDs can have serious side effects, including:

• Bleeding.
• Ulcers.
• Stomach pain.
• Bowel complications.

How soon after treatment will my child feel better?

Your child should feel better as soon as the NSAIDs take effect, usually around an hour. The same goes for icing their knee.

That pain relief will be fast-acting, but it doesn’t mean your child’s patellar tendon has healed. Resting and avoiding the activity that caused their Sinding-Larsen-Johansson syndrome is the most important part of your child’s treatment.

Make sure to follow the plan your provider gives you. They’ll tell you how long it will take for your child to feel better, based on their specific case of Sinding-Larsen-Johansson syndrome.

How can I reduce my child’s risk for Sinding-Larsen-Johansson syndrome?

You can help your child prevent any damage to their patellar tendon before it occurs. One of the best ways to do that is making sure they have plenty of time to rest and recover between sports seasons.

More children and teens are diagnosed with Sinding-Larsen-Johansson syndrome than ever before. The biggest cause of this is playing or training for a single sport year-round. As more kids specialize in one sport or activity, their bodies don’t have time to rest and recover properly. Children and teens should avoid specializing in one sport until their late teens to reduce their risk for all injuries, including SLJ.

How can I prevent Sinding-Larsen-Johansson syndrome?

The best way to prevent Sinding-Larsen-Johansson syndrome is stretching the quadriceps (thigh muscles) regularly. The more flexible your child’s legs are, the less pressure is put on their tendons.

In general, it’s best to take a few preventive steps to reduce stress on the patellar tendon including:

• Stretching before and after playing sports.
• Resting and taking breaks.
• Don’t "play through the pain."

What can I expect if my child has Sinding-Larsen-Johansson syndrome?

If your child is diagnosed with Sinding-Larsen-Johansson syndrome, expect them to spend time away from sports and intense physical activity. SLJ is a temporary injury, but it takes time for the tendon to heal.

How long does Sinding-Larsen-Johansson syndrome last?

How long Sinding-Larsen-Johansson syndrome lasts depends on how severe the initial damage to your child’s patellar tendon is. The pain and inflammation may go away in a few days or weeks, but kids will often need to avoid sports for up to several months to prevent longer-term damage to their knees.

When can my child go back to school?

Your child shouldn’t need to miss school while they’re recovering from Sinding-Larsen-Johansson syndrome. Ask your provider if your child needs modified gym class or physical education requirements to avoid putting stress on their knee while it heals.

Outlook for Sinding-Larsen-Johansson syndrome

Sinding-Larsen-Johansson syndrome is a temporary condition, but it can be frustrating for kids to miss out on playing a sport they love. Make sure your child understands what they need to do to help their body rest, recover and heal, and why they need to take a break from their sports or activities that caused SLJ.

When should I see my healthcare provider?

Visit your healthcare provider right away if your child notices any new pain in their knee, especially if it’s combined with swelling. Your provider will help you determine what’s causing your child’s pain, and if it’s Sinding-Larsen-Johansson syndrome or something more serious, like a fracture.

What questions should I ask my doctor?

• Which tests will my child need?
• How long should my child stop playing sports?
• Is this Sinding-Larsen-Johansson syndrome or Osgood-Schlatter disease?
• Which stretches will help prevent Sinding-Larsen-Johansson syndrome in the future?

A note from Cleveland Clinic

It’s always scary when your child is in pain. When kids hurt their joints, it’s natural to worry about long-term consequences. Fortunately, Sinding-Larsen-Johansson syndrome is a temporary injury that shouldn’t have any impact on your child’s knee in the future. Make sure your child knows that even if they have to miss a season of their favorite sport to heal, it’s worth it.