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Sinding-Larsen-Johansson Syndrome

By Tristyn Kinser, MS, LAT, ATC

What is Sinding-Larsen-Johansson Syndrome?

Sinding-Larsen-Johansson Syndrome is a common overuse injury characterized by tenderness and inflammation at the bottom of the patella (kneecap), where the patellar tendon attaches. The patellar tendon attaches to the tibia (shin bone) via the bottom of the kneecap.

Sinding-Larsen-Johansson Syndrome Knee Tendons

Image of Knee Tendons Anterior View

This is not to be confused with Osgood Schlatter’s disease, which is pain at the bottom attachment of the patellar tendon. The patella is attached to your shin bone by the patellar tendon. While growing, the tendon connects to a growth plate at the bottom of the patella. Repeated stress or vigorous exercise can cause this growth plate to be irritated.

What Causes Sinding-Larsen-Johansson Syndrome?

Overuse is the typical cause for Sinding-Larsen-Johansson (SLJ) syndrome in growing adolescents. When the quadriceps muscles repeatedly contract, this creates a pulling force on the bottom of the kneecap. This happens most commonly in children who are active during their growth spurts. The quadriceps are known as the large muscle group on the front of the thigh. This muscle attaches to the kneecap (tendons are responsible for attaching our muscles to our bones).

When we straighten our legs to walk or run, the quadriceps pull at the patellar tendon, so the lower leg moves forward. This force puts stress on the bottom of the knee cap at the growth plate. While children are going through growth spurts, the bones and muscles do not always grow at the same speed. This imbalance means that as the bones grow longer, the muscle becomes tight, putting painful stress on the growth plate where the tendon meets the bone. Poor biomechanics and tightness in the muscles of the lower extremities also contribute to Sinding-Larsen-Johansson syndrome.

Who is at Risk for SLJ Syndrome?

Children, particularly boys aged 10-14 years who:

  • Are overweight
  • Participate in sports
  • Incorrect training techniques
  • Switch between phases of inactivity and activity
  • Have poor biomechanics
  • Wear poorly fitting shoes
  • Have weak quadriceps
  • Have poor flexibility

Recognizing Signs and Symptoms of SLJ

Sinding-Larsen-Johansson syndrome is characterized by the following:

  • Localized pain at the front of the knee
  • Pain increases with running, squatting, kneeling
  • Limping after exercise
  • Tightness in leg muscles
  • Tenderness over kneecap
  • Bump at the bottom of the kneecap
  • Pain relieved by rest

How to Treat SJL

While most cases of Sinding-Larsen-Johansson syndrome typically resolve in a few weeks, physical therapy has been very successful in managing pain. While undergoing treatment, patients will typically complete the following regimen:

  • Phase 1
    • Immediate removal from sports-related activities
    • Recommend low impact activities such as biking and swimming
    • Assessment of hip, knee, and foot biomechanics
    • Implementation of a patellar strap or KT tape to relieve tension from the tendon
    • Referral to MD if the need for anti-inflammatories
    • Rest
  • Phase 2
    • Stretching of the quadriceps, IT band, hamstrings, hip flexors, calves
    • Massage
    • Foam Rolling
    • Electrotherapy
    • Ice
  • Phase 3
    • Strengthening of the quadriceps to relieve force from tendon
    • Strengthening of lower extremity musculature
    • Typically with physical therapy and rest, an individual with Sinding-Larsen-Johansson syndrome returns to play within 6-14 weeks.
    • 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 cold compress to the affected area 15-20 mins every few hours. Do this for 2-3 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.

How to Prevent SLJ

Limiting activities that cause pain is the key to the prevention of Sinding-Larsen-Johansson syndrome. Always maintain a good warm-up and stretching regimen before beginning activities or playing sports. As always, consult your MD or sports medicine expert for a full evaluation and therapeutic exercises specific to you.

If you think you are suffering from SLJ syndrome, or another medical condition of the knee, book an appointment with one of our knee Physicians at Jacksonville Orthopaedic Institute or call JOI-2000 today!

By: Tristyn Kinser, MS, LAT, ATC