What Is Sinding Larsen Johansson Syndrome?

Sinding Larsen Johansson Syndrome is a traction-related knee condition that affects active children and teenagers. It occurs at the lower pole of the kneecap, where the patellar tendon attaches. During growth, this area is more sensitive to load from running, jumping and rapid changes in training volume.

This condition is most common in children aged 10 to 13 who play sports involving repetitive impact, sprinting or jumping. The symptoms often appear gradually and may worsen during periods of rapid growth.

Sinding Larsen Johansson Syndrome is closely linked to other growth-related knee conditions such as Osgood-Schlatter Disease and Patellar Tendinopathy.

What Causes Sinding Larsen Johansson Syndrome?

SLJ develops when repeated pulling forces act on the bottom of the kneecap. These forces come from the quadriceps muscle group during activity. When bones are still developing, the growth plate at the inferior patella is more vulnerable to stress.

Common contributing factors include:

• Rapid growth during puberty
• High training volume or sudden workload increases
• Sports involving running and jumping
• Tight quadriceps, hamstrings or calf muscles
• Reduced shock absorption or poor foot control

Because the bone and tendon structures are changing quickly during adolescence, this area can become irritated if training loads remain too high.

Symptoms of Sinding Larsen Johansson Syndrome

Children often report a gradual onset of pain at the lower part of the kneecap. Symptoms may include:

• Pain at the bottom of the kneecap with running, jumping or kicking
• Swelling or local tenderness around the patellar tendon attachment
• Increased pain with stairs, squatting or kneeling
• Limping after sport or training
• Tightness through the front of the thigh or calf

Symptoms often improve with rest and flare with heavy activity.

How Is Sinding Larsen Johansson Syndrome Diagnosed?

A physiotherapist or doctor can diagnose SLJ through clinical assessment. Imaging, such as X-ray or MRI, is used only when symptoms are severe or when ruling out other knee conditions.

For general knee-tendon information, MedlinePlus offers a useful overview:
patellar tendon resource.

Your physiotherapist will assess:

• Tendon and growth plate sensitivity
• Strength through the quadriceps and glutes
• Movement control during squatting and jumping
• Flexibility of the lower limb muscles
• Foot posture and running mechanics

Early assessment helps guide safe activity levels and prevents long-term irritation.

Treatment for Sinding Larsen Johansson Syndrome

Treatment focuses on reducing irritation, improving movement control and guiding a safe return to sport. Most children recover well with load management and a structured exercise program.

Phase 1 — Settle Irritation

• Reduce high-impact activity such as jumping and sprinting
• Continue low-impact exercise such as cycling or swimming
• Use an infrapatellar strap to reduce traction load
• Consider taping to support the tendon during activity
• Ice may assist short-term symptom relief

Phase 2 — Improve Flexibility

Tight quadriceps, hamstrings and calf muscles increase traction forces on the kneecap. Your physiotherapist will prescribe gentle stretches and may use massage or soft tissue techniques to reduce muscle tension.

Phase 3 — Strengthen Key Muscles

Strengthening helps reduce load at the growth plate. Common targets include:

• Quadriceps
• Hamstrings
• Glutes
• Calf muscles
• Foot arch control

Exercises progress from simple movements to sport-specific drills as symptoms improve.

Phase 4 — Return to Sport

Your physiotherapist will guide progression back to:

• Running drills
• Jumping and landing mechanics
• Change-of-direction tasks

Activity should not cause pain that lasts longer than 24 hours after training.

Prognosis

Sinding Larsen Johansson Syndrome is a self-limiting condition. Symptoms usually settle as the growth plate matures. Many children improve within 6–14 weeks when training loads are adjusted. A full resolution typically occurs when the kneecap growth plate closes.

Your physiotherapist will provide an individualised plan to support your child’s recovery and long-term knee health.

Related Articles

1. Kids Leg Pain: Understanding Youth Injuries
2. Osgood-Schlatter Disease
3. Patellofemoral Pain Syndrome
4. Quadriceps Tendinopathy
5. Patellar Tendinopathy
6. Avulsion Fracture Recovery

References

1. Maruszczak K, Madej T, Gawda P. Lower limb osteochondrosis and apophysitis in young athletes: a comprehensive review. Applied Sciences. 2024;14(24):11795.
2. Wilczyński B, Taraszkiewicz M, de Tillier K, Biały M, Zorena K. Sinding-Larsen-Johansson disease: clinical features, imaging findings, conservative treatments and research perspectives—a scoping review. PeerJ. 2024;12:e17996.
3. Brenner JS, Watson A; Council on Sports Medicine and Fitness. Overuse injuries, overtraining, and burnout in young athletes Pediatrics. 2024;153(2):e2023065129.
4. de Lucena GL, dos Santos Gomes C, Guerra RO. Prevalence of Osgood-Schlatter and Sinding-Larsen-Johansson diseases in Brazilian adolescents. J Pediatr (Rio J). 2020;96(5):605–612.
5. Schultz M, Tol JL, Veltman L, van der Kaaden L, Reurink G. Osgood-Schlatter disease in youth elite football: minimal time-loss and no association with clinical and ultrasonographic factors. Phys Ther Sport. 2022;55:257–264.

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