ConditionBones, joints & muscles
Sinding-Larsen-Johansson Syndrome
Sinding-Larsen-Johansson (SLJ) syndrome is an overuse injury that causes pain and tenderness at the lower tip of the kneecap in growing children, typically aged 10 to 14. Repeated pulling by the patellar tendon during running and jumping irritates the growth area at the bottom of the kneecap. It is common in basketball, volleyball, soccer, gymnastics and dance. It is closely related to Osgood-Schlatter disease, which affects the shinbone just below. SLJ settles with activity changes, ice, stretching and time, usually within 3 to 12 months, and does not cause lasting damage.
Also called: SLJ syndrome, Sinding-Larsen-Johansson disease, jumper's knee in adolescents, inferior pole patellar apophysitis
At a glance
- What it is
- Irritation of the growth area at the bottom of the kneecap from repeated tendon pulling.
- Who gets it
- Active children aged about 10 to 14, during growth spurts.
- Symptoms
- Pain and tenderness at the lower tip of the kneecap, worse with running, jumping, kneeling and stairs.
- Diagnosis
- Examination; X-ray sometimes.
- Treatment
- Relative rest, ice, stretching, strengthening, knee strap; heals with growth.
When to get help
See a doctor within a day or two
- Sudden severe knee pain after a jump or fall with inability to straighten the knee or bear weight (possible fracture or tendon injury)
- Knee pain with fever, redness and warmth, or a swollen hot joint
- Night pain, pain at rest, or a limp without a clear cause
Book a routine appointment
- Knee pain below the kneecap that keeps returning with sport
- Pain that has not improved after 4 to 6 weeks of reduced activity
- Pain affecting both knees, or hip pain referring to the knee
Usually safe to manage at home
- Mild aching at the bottom of the kneecap after sport in an active child, improving with rest and ice
Why it happens
In children, the ends of bones have growth plates and growth centers (apophyses) where tendons attach. These areas are weaker than adult bone. During growth spurts, bones lengthen faster than muscles and tendons stretch, increasing tension. Repeated pulling by the strong quadriceps through the patellar tendon at the lower tip of the kneecap causes irritation, small stress injuries and sometimes small pieces of bone to form in the tendon.
Symptoms
- pain and tenderness at the bottom tip of the kneecap
- mild swelling at that spot
- pain with running, jumping, squatting, kneeling and climbing stairs
- stiffness after rest
- sometimes a limp after sport
It can affect one or both knees.
Risk factors
- age 10 to 14 and growth spurts
- sports with running, jumping and kneeling: basketball, volleyball, soccer, track, gymnastics, figure skating, dance
- tight quadriceps and hamstrings
- sudden increases in training load
- playing one sport year-round
SLJ vs Osgood-Schlatter vs jumper's knee
| SLJ syndrome | Osgood-Schlatter disease | Jumper's knee (patellar tendinitis) | |
|---|---|---|---|
| Pain location | Bottom tip of kneecap | Bony bump on the shin below the knee | Patellar tendon just below kneecap |
| Typical age | 10 to 14 | 10 to 15 | Older teens and adults |
| Cause | Traction on kneecap growth area | Traction on shinbone growth area | Tendon overuse |
Other causes of knee pain in young athletes include patellofemoral pain syndrome, osteochondritis dissecans and, in the hip, slipped capital femoral epiphysis, which can cause knee pain and must not be missed.
Diagnosis
A doctor diagnoses SLJ by examining the knee and finding tenderness at the lower pole of the kneecap. X-rays may be done to rule out fractures and can show small calcified fragments. Ultrasound or MRI are rarely needed.
Treatment
Activity modification
- reduce or pause activities that cause pain, especially jumping and running, until pain settles
- stay active with low-impact exercise such as swimming or cycling if comfortable
- return gradually once pain-free with daily activities
Symptom relief
- ice for 15 to 20 minutes after activity
- ibuprofen or acetaminophen (paracetamol) as needed, following the label dose for age; no aspirin for children
- a patellar tendon strap or knee sleeve may ease pain during sport
Exercises
- stretching the quadriceps, hamstrings and calves
- strengthening the hips and core
- gradual loading of the quadriceps under the guidance of a physical therapist
Surgery is almost never needed.
Outlook
SLJ syndrome is self-limiting. Symptoms usually resolve within 3 to 12 months and stop completely once the growth center fuses in mid-adolescence. Flare-ups can occur with increased activity during growth. Long-term problems are rare.
Frequently asked questions
What is Sinding-Larsen-Johansson syndrome?
It is an overuse condition in growing children in which the patellar tendon repeatedly pulls on the growth area at the bottom of the kneecap, causing pain and tenderness. It is common in children aged 10 to 14 who play running and jumping sports.
How is SLJ different from Osgood-Schlatter disease?
Both are traction injuries at growth centers. SLJ affects the bottom tip of the kneecap, while Osgood-Schlatter affects the bump on the shinbone just below the knee. They are managed in the same way.
Can my child keep playing sports with SLJ syndrome?
Children can often continue sport at a reduced level if pain is mild and settles quickly afterward. If pain causes limping or affects performance, they should rest from aggravating activities until it improves.
How long does Sinding-Larsen-Johansson syndrome last?
Most children improve within 3 to 12 months with activity modification and exercises. It resolves completely once growth around the kneecap is finished, usually by mid-adolescence.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Orthopaedic Surgeons (OrthoInfo): Knee pain in young athletes
- American Academy of Pediatrics (HealthyChildren.org): Knee pain in children
- Boston Children's Hospital: Sinding-Larsen-Johansson syndrome
- Children's Hospital of Philadelphia: Sinding-Larsen-Johansson syndrome
- American Medical Society for Sports Medicine: Overuse injuries in youth sports