Sinding-Larsen-Johansson Syndrome
Knee pain at the lower tip of the kneecap in growing teens
Quick Facts
- Type: Growth-related knee condition
- Main area: Lower tip of the kneecap
- Common in: Active children and teens during growth spurts
- Outlook: Usually resolves as growth finishes
Overview
Sinding-Larsen-Johansson (SLJ) syndrome is a growth-related cause of knee pain in active children and adolescents. It affects the lower tip (pole) of the kneecap, where the patellar tendon attaches to a still-developing area of bone. Repeated pulling of the tendon during running and jumping irritates this growth region, causing pain and tenderness at the bottom of the kneecap.
It is closely related to other adolescent overuse knee conditions and is sometimes thought of as a younger person's version of jumper's knee. Like other growth-plate conditions, it is self-limiting and does not damage the joint, and it typically settles as the skeleton matures. Management focuses on easing pain while allowing safe activity.
Symptoms
Symptoms focus on the lower part of the kneecap and relate to activity.
- Pain and tenderness at the lower tip of the kneecap
- Pain that worsens with running, jumping, climbing stairs, squatting, and kneeling
- Swelling or thickening over the lower kneecap
- Pain that eases with rest and flares with sport
- Stiffness or tightness in the thigh muscles
- Discomfort when straightening the knee against resistance
As with similar conditions, the pain often comes and goes over months during the growth period, flaring with high activity.
Causes
SLJ syndrome results from repeated stress on a growth area during years of rapid growth.
- Repetitive tendon pull: Running, jumping, and kicking repeatedly load the patellar tendon at its attachment to the lower kneecap.
- Growth spurts: During rapid growth, bones outpace muscles and tendons, increasing tension at the attachment.
- Tight thigh muscles: Quadriceps tightness adds to the pull on the area.
- High training loads: Frequent or intense jumping sport with limited recovery.
The combination of an immature, growing kneecap and repeated athletic stress leads to the irritation.
Risk Factors
- Age during the adolescent growth spurt (roughly 10 to 14 years)
- Jumping and running sports such as basketball, volleyball, and soccer
- Rapid recent growth
- Tight quadriceps and hamstrings
- High training frequency with limited rest
Diagnosis
SLJ syndrome is usually diagnosed clinically.
- History: A growing, active child with activity-related pain at the bottom of the kneecap.
- Physical exam: Tenderness over the lower pole of the kneecap, with pain reproduced by straightening the knee against resistance.
- Imaging: Not usually required. X-rays may be used to confirm the diagnosis or rule out other causes if pain is severe, one-sided, or atypical, or if there was an injury.
Treatment
Treatment is conservative, aiming to control pain while keeping the child active within comfort.
- Activity modification: Reducing or adjusting high-impact activity during flares, guided by pain rather than enforcing complete rest.
- Ice: Applying ice to the lower kneecap after activity.
- Stretching and strengthening: Stretching the quadriceps and hamstrings and strengthening the thigh to reduce tension at the attachment.
- Pain relief: Over-the-counter pain medicine for flares, used as advised.
- Support: A patellar strap can ease pain for some during activity.
- Reassurance: Explaining that the condition is self-limiting and does not harm the joint.
Symptoms usually resolve once growth is complete, often within several months to a year or two of onset.
Prevention
- Keep the thigh and hamstring muscles flexible
- Strengthen the thigh muscles to support the knee
- Warm up before sport and increase training gradually
- Balance jumping and running with adequate rest
- Respond to knee pain during growth spurts by adjusting activity
- Use a patellar strap during sport if it improves comfort
When to See a Doctor
See a clinician if a child has persistent knee pain, if the pain is severe, present at rest or at night, or if the knee is hot, red, or significantly swollen, or if there is a limp or difficulty bearing weight, since these are not typical of SLJ syndrome and need evaluation. Sudden severe pain after a fall or jump, particularly with inability to straighten the leg, should be assessed promptly.
Frequently Asked Questions
What is the difference between SLJ syndrome and Osgood-Schlatter disease?
Both are growth-related overuse conditions affecting the patellar tendon in active teens. SLJ syndrome involves the lower tip of the kneecap, while the other condition involves the bump on the upper shinbone where the tendon attaches. Both are self-limiting and managed similarly.
Can my child keep playing sports with SLJ syndrome?
Usually yes, within their comfort. Activity can be guided by pain, with reductions during flares rather than complete rest. Ice after sport, stretching, strengthening, and a patellar strap often help. See a clinician if pain is severe or causes a limp.
Will SLJ syndrome go away on its own?
Yes. In almost all cases it resolves as the child finishes growing and the kneecap matures, often within several months to a couple of years. It does not damage the joint. Persistent severe pain or a hot, swollen knee is not typical and should be checked.
What helps relieve the knee pain of SLJ syndrome?
Reducing high-impact activity during flares, icing the lower kneecap after sport, stretching the thigh and hamstrings, strengthening the thigh, and using a patellar strap can all help. Over-the-counter pain medicine may be used for flares as advised. The condition ultimately settles with skeletal maturity.
References
- American Academy of Orthopaedic Surgeons (AAOS). Adolescent Knee Pain.
- Nemours KidsHealth. Osgood-Schlatter Disease and Related Knee Conditions.
- MedlinePlus, U.S. National Library of Medicine. Knee pain.
- American Academy of Family Physicians (AAFP). Apophysitis in Young Athletes.