top of page
  • Writer's pictureDaniel Selin

Sinding-Larsen-Johansson disease (SLJ)

Updated: Apr 14, 2023

Sinding-Larsen-Johansson disease, SLJ, apophysitis, osteochondrosis, patellar pain, jumper's knee, anterior knee pain, knee pain in children and adolescents, knee strain injury, overuse injury, tendon pain, growing pains, growth plate pain.

Sinding-Larsen-Johansson (SLJ) disease, also known as jumper's knee in children, is a condition that affects the attachment of the patellar tendon to the lower part of the patella due to osteochondrosis and traction apophysitis of the patellar ossification center. This is similar to Osgood-Schlatter disease, but in this case, the increased traction stress is exerted on the lower end of the patella instead of the tibial tuberosity. SLJ disease usually occurs during adolescence, at the time of the growth spurt. It causes local pain that is aggravated by physical activity. Typically, there is local tenderness and soft tissue swelling in the front of the knee. The condition occurs as a result of repetitive stress, such as jumping and running. Typical sports that are more likely to cause this condition include football, basketball, volleyball, gymnastics, and other sports that involve a lot of running, jumping, and especially sprinting.

Rapid sprints, changes of direction, and stops on hard surfaces seem to particularly irritate attachment areas. This may be one reason why apophysitis is now found slightly more frequently, especially among football players. Sand fields are rapidly being replaced by artificial turf, which allows for significantly faster changes of direction, sprints, and stops. On sand fields, players slid when starting and stopping, which reduced the load on the growth areas as kinetic energy flowed into the sand. This also reduced the risk of injury and didn't place as much stress on the tissues as is done today.

Apophysitis and osteochondrosis

Apophysitis refers to a situation in which the bone's growth area, apophysis, is subjected to repeated traction stress without adequate recovery. This leads to microscopic damage to the growth area, which over time can become more extensive and cause pain, swelling, and pressure sensitivity.

Apophysitis is a general term for pain at the attachment site of the growth area and the skeleton muscle and does not necessarily indicate an inflammatory condition, although the suffix "-itis" suggests this. Apophysitis can occur on any growth area, depending on the load generated by the sport in question. The most typical apophysitis is found in the knee and heel areas. Advanced apophysitis can lead to osteochondrosis.

Osteochondrosis is a more severe skeletal growth disorder than apophysitis, which may involve inflammation, a hardening or widening of the growth area, and bone necrosis. The cause is often a circulatory disorder in the bone or growth plate, resulting in local necrosis, although bone regeneration often follows.

The root cause of osteochondrosis is not known, but the same factors that cause apophysitis are often involved. Genetic factors and anatomical anomalies also contribute to the development of osteochondrosis. The most typical apophysitis and osteochondrosis are Osgood-Schlatter disease, Sever's disease, and Sinding-Larsen-Johansson disease.



SLJ disease usually develops during the bone maturation phase, which is around 8-12 years of age in girls and 10-14 years of age in boys. Collectively, it can be observed that the condition is most commonly seen between the ages of 8-14 and is slightly more common among boys than girls. It is an overuse condition that occurs through the patellar tendon in the growth plate located in the lower part of the patella. Repetitive pulling stress causes micro-tears, fractures, and inflammation of the blood vessels, resulting in swelling, pain, and tenderness in the affected area.

Factors that predispose to the condition include weakened flexibility of the quadriceps, relative muscle weakness, and biomechanical challenges in the lower extremity. The causes may also be related to increased overall load, under-recovery, too one-sided diet or too little sleep. Therefore, when assessing the condition, it is important to consider all background factors so that the condition can be treated as effectively and individually as possible.

The condition is often compared to "jumper's knee," which is a common cause of anterior knee pain in adults. The similarities are increased load on the knee, local pain in the front of the knee that worsens during or after exercise, but in adults the source of pain is often the patellar tendon or its attachment, whereas in children the origin of pain is more likely to be in the patella's growth area, which is no longer present in adults.

SLJ ja OS tauti

Risk factors

  • Gender; more common in girls than in boys

  • Age; boys aged 10-14, girls aged 8-12

  • Sudden growth spurt

  • Repeated stress to the knee, such as jumping and running

  • Inadequate recovery

  • Repetitive or early specialization in one sport

  • Weakened flexibility or strength in the quadriceps

  • Biomechanical factors and lower limb alignment issues



Characteristic symptoms of SLJ disease include knee pain and a feeling of warmth in the patella, often after exercise. As the condition progresses, pain may also occur during exercise and at rest. Knee extension can be painful, and there may be local swelling in the soft tissues. The knee is often sensitive to touch, and pain can also cause changes in walking and running style. Mobility becomes uneven, and the child may begin to avoid unnecessary knee stress. It is typical for knee pain to worsen, especially when climbing stairs, squatting, kneeling, jumping, and running.



The most important treatment is to stop painful exercise and get enough rest. Since exercise breaks can be long, it is important to find an alternative form of exercise that is suitable and interesting for the young athlete while their favorite hobby is on hold. In addition, the time should be used wisely to develop sport-specific techniques that improve athletic abilities without causing knee pain.

The flexibility and elasticity of the quadriceps should be improved with a light and progressive stretching program and manual treatment. Load coming through the patellar tendon can also be reduced by using knee braces or support taping. Lower limb biomechanics and functional control should be improved along with power production. Problems with power production, especially in the pelvic and gluteal area, can cause knees to turn inward during squats and alter the load on the knees.

Cold therapy should be used generously and systematically during acute pain episodes. Careful consideration should also be given to shoe and equipment choices. In particularly difficult cases, the knee may need to be casted so that the area of bone growth can calm down.

Surgical treatment may also be considered if there is a painful loose piece of bone under the patellar tendon in the knee. Surgery is often not performed until growth has stopped. However, surgical treatment is the rarest treatment option, and the prognosis for recovery is excellent with proper care.



Physiotherapy always starts with a thorough examination of the background factors, based on which an individual rehabilitation program can be created. The underlying factors must be differentiated and the ones that have caused the pain or discomfort must be identified.

The examination of background factors aims to find the reasons for the occurrence of the problem. Typically, these can be roughly divided into three groups:

  1. Excessive load or insufficient recovery

  2. Rapid growth spurts

  3. Biomechanical factors that cause excessive strain on the patellar tendon

In physiotherapy, it is important to discuss the patient's condition and help them understand the background and ways to improve it. Rehabilitation usually includes a mixture of treating possible muscle tightness manually, increasing elasticity according to an individual stretching program, improving lower limb biomechanical properties, strength training, and control and balance training. Rehabilitation is carefully planned according to the background factors, so what works for one person may not be the best treatment for another. Therefore, it is recommended to consult a physiotherapist who specializes in lower limb or children's and adolescents' overuse injuries as soon as possible.

The physiotherapist also provides precise instructions on when it is safe to return to sports and how to do it. Here are a few examples of goals that should be achieved before returning to sports:

  • No more pain or swelling in the patella in everyday life

  • The injured knee can be fully extended and flexed without pain

  • The knee and leg have regained normal strength without pain

  • Jogging and sprints can be done without limping

  • No more tenderness or sensitivity in the patella

  • Ability to jump on both legs without pain

So, if you experience pain or discomfort in your legs, don't wait too long to see a physiotherapist and get back on track with an individualized rehabilitation program.


Self care

Here are some specific exercises and tips that may be helpful for someone with Sinding-Larsen-johansson's disease:

Week 1-4

  1. Activity modification (avoid activities that aggrevate your knee pain)

  2. Static holds against the wall for thigh activation (10 repetitions, 30 seconds each, once daily)

  3. Pelvic lifts, preferably with excess load (3 sets of 10 repetitions, every other day)

From week 5 onwards

  • Excercise with body load (squats, pelvic lifts, wall holds etc.)

  • Gradually increase knee loading activities using the activity ladder:

  1. Light walking/cycling

  2. Faster walking/medium to hard cycling

  3. Slow running

  4. Stairs

  5. Running in medium pace

  6. Skipping

  7. Jumping

  8. High speed running, turning and jumping

  9. Warm-up and 50% training

  10. Warm-up and full training

  11. Match/competition

Avoid doing exercises that aggrevate your pain intensity over a 5/10 on the visual analogue scale (VAS) or activities that maintain an increased pain sensation in the knee for over 24 hours after stopping with that exercise.

Cold therapy: Apply cold to the sore area for 15-20 minutes several times a day until the daily knee pain has stopped. After this, the use of cold is still advisable when the knee becomes sore.

Consult a physical therapist: If your pain persists despite self-care measures or is interfering with your daily activities, consult a physical therapist. They may recommend additional treatments such as manual therapy, individualized exercise program or custom insoles.

60 views0 comments

Recent Posts

See All


bottom of page