Sinding-Larsen-Johansson (SLJ) syndrome is pain at the bottom of the kneecap (patella). It is caused by swelling and irritation of the growth plate there. A growth plate is a layer of cartilage near the end of a bone where most of the bone's growth happens. It is weaker and more at risk for injury than the rest of the bone.
SLJ syndrome goes away when a teen is done growing and usually doesn't cause lasting problems.
SLJ syndrome typically causes pain near the bottom of the kneecap. A teen also might have:
Sinding-Larsen-Johansson syndrome is caused by repeated stress on the kneecap growth plate. The patellar tendon connects the kneecap to the shinbone (tibia). Every time the leg is straightened, the patellar tendon puts stress on the growth plate.
Sinding-Larsen-Johansson syndrome usually happens in teens who are:
SLJ syndrome is an overuse injury. This means it happens because someone does the same movements over and over again.
To diagnose SLJ syndrome, health care providers ask about physical activities and do an exam.
Testing usually isn't needed. But sometimes doctors order an X-ray or magnetic resonance imaging (MRI) scan to check for other knee problems.
Someone with SLJ syndrome needs to limit activities that cause so much pain that it's hard to do that activity. For example, if you feel a little pain when running, it's OK to keep running. But if running causes a limp, stop and rest. When the pain is better (usually after a day or two), you can try the activity again.
To keep leg muscles strong and flexible while you get better, your doctor will recommend physical therapy (PT) or a home strengthening and stretching program. It doesn't happen often, but some teens might need to take a break from sports for a few weeks.
To feel more comfortable while healing from SLJ syndrome:
Teens with SLJ syndrome usually can do their normal activities, including sports, as long as:
SLJ syndrome may come and go until you're done growing (usually mid-to-late teens). To help prevent SLJ syndrome from coming back:
When exercising or playing sports:
Reviewed by: Amy W. Anzilotti, MD
Date Reviewed: Nov 26, 2019