Sinding Larsen Johansson Syndrome

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 child is done growing and usually doesn’t cause lasting problems.



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.



Common symptoms related to patellar tendonitis are:

  • Tenderness around the kneecap
  • Pain that increases with exercise or activities such a running, climbing stairs, or jumping
  • Swelling and tenderness around the kneecap
  • Tenderness



To determine if your child has SLJ our specialists will perform a physical exam that includes flexibility tests, stress tests, muscle tests and gait analysis. These additional tests will help our specialized team better understand your child’s condition, assess range of motion and identify abnormalities that might occur in bone alignment or muscle function.

After a physical exam, our specialists may also order imaging tests such as an X-ray, MRI, or ultrasound.



Possible non-surgical treatments your doctor may offer or recommend to treat your child’s Sinding-Larsen-Iohansson Syndrome include:

  • Home exercise programs or Physical therapy
  • Activity modification or rest
  • Bracing


At-Home Care

Common at-home treatment options for patellar tendonitis include:

  • Icing the Area: Put ice packs on your child’s knee for 20–30 minutes every 3-4 hours for the first 2-3 days. If pain does not go away, contact your healthcare provider.
  • Elevating the Injured Limb: Elevate your child’s lower leg by placing it on a pillow when your child is lying down. Elevating it above the heart level can help reduce swelling and pain.
  • Taking Non-Prescription Medication: Take a non-steroidal, anti-inflammatory drug (NSAID), such as ibuprofen as recommended by your healthcare provider.
  • Stretching and strengthening: Your doctor may recommend doing stretches or exercises at home. These are designed to stretch the affected knee, maintain range of motion in the joint and strengthen your child’s knee.
  • Bracing: Protective knee pads for particular sports may be recommended


Rehabilitation Exercises

Below are common exercises a doctor may recommend to help recover after patellar tendonitis. Always check with your doctor to find out which exercises are right for your child.



Hamstring Stretch

  • Lie on back and bring the affected leg towards the chest.
  • Grab the back of the thigh and try to extend the leg.
  • Your child may also try this with a towel around the foot if it is more comfortable.
  • Hold for 30-60 seconds. Repeat 3 times.

Quadriceps Stretch

  • Stand sideways to a wall, about an arm’s length away from the wall, with your injured leg towards the outside.
  • Facing straight ahead, keep the hand nearest the wall against the wall for support.
  • With your other hand, grasp the ankle of your injured leg and pull your heel up toward your buttocks. Do not arch or twist your back.
  • Hold this position for 30 seconds.
  • Repeat three times.
  • Note: This may also be done while lying on the opposite side and grasping the ankle of the affected leg. Do not arch or twist your back. Hold this position for 30 seconds. Repeat three times.


Range of Motion

Patellar Mobility

  • Sit with injured leg outstretched and the muscles on top of thigh relaxed.
  • Take index finger and thumb, and gently press kneecap down toward foot.
  • Hold for 10 seconds, then return to the starting position.
  • Pull kneecap up toward waist and hold for 10 seconds, then return to the starting position.
  • Push kneecap inward toward other leg gently and hold it for 10 seconds.
  • Repeat these steps for approximately 5 minutes.



Quadriceps Set

  • Sit on floor with injured leg outstretched.
  • Tighten muscles at the top of thigh by pushing the back of knee down into the floor.
  • Concentrate on contracting the inside part of the thigh.
  • Hold for 5 seconds.
  • Repeat 3 times. Do 3 sets of 15.

Straight Leg Raise

  • Sit on the floor with the injured leg straight and the other leg bent, foot on the floor.
  • Pull the toes of the injured leg in as far as possible, while pressing the back of the knee down and tightening the muscles on the top of the thigh.
  • Raise the leg six to eight inches off the floor and hold for 5 seconds.
  • Slowly lower back to the floor.
  • Complete 3 sets of 15.

Weight Lifting (Leg Extension)

  • This exercise requires a weightlifting bench with a leg extension attachment.
  • Sit on bench with the weight attachment in front of lower legs.
  • Extend knees by straightening legs, taking care straighten legs completely.
  • Use enough weight to cause fatigue, but not pain.
  • Do 3 sets of 15.


When Will My Child Return to Play?

SLJ syndrome may come and go until you’re done growing (usually mid-to-late teens). To help prevent SLJ syndrome from coming back:

  • Stop doing an activity if knee pain or swelling comes back. Then, try to limit your activity until the pain or swelling goes away.
  • If possible, avoid or limit activities that put a lot stress on the knees, such as walking up and down stairs, lifting heavy objects, and squatting.

When exercising or playing sports:

  • Work with a coach or trainer to make sure you use proper technique.
  • Stretch before and after sports.
  • Increase the length and intensity of your workout slowly.
  • Wear shock-absorbing insoles in your sneakers and cleats.
  • Put a heating pad or warm washcloth on the knee for 15 minutes before exercise and sports.
  • Put ice on the knee for 15 minutes after the activity (with a towel between the ice and the skin).
  • Wear protective knee pads, especially for wrestling, basketball, and volleyball.


See more information

Sports Medicine


We provide exceptional care to patients and their families, putting children in the best hands for successful diagnosis, treatment and rehabilitation.

View All Specialties


It’s easy and convenient to make an appointment.

Request An Appointment