Sinding-Larsen-Johansson Syndrome
What is Sinding-Larsen-Johansson syndrome?
Sinding-Larsen-Johansson syndrome (SLJ) is a growth-related condition affecting the knee in adolescents, characterised by pain and tenderness at the inferior pole of the patella (the bottom tip of the kneecap) — the point where the patellar tendon attaches to the patella. It occurs during periods of rapid growth when the bones are developing faster than the surrounding soft tissues can accommodate, creating traction stress at the developing apophysis (growth plate attachment) of the inferior pole.
It is sometimes confused with Osgood-Schlatter disease, which affects the tibial tuberosity — the bony bump just below the kneecap — rather than the kneecap itself. Both are growth-related traction apophysitis conditions and both are common in active adolescents, but the location of pain distinguishes them. SLJ pain is at the bottom of the kneecap; Osgood-Schlatter pain is lower, at the shin bone. Some teenagers have both simultaneously.
SLJ primarily affects boys aged 10 to 13 and girls aged 8 to 12 — the age range corresponding to peak adolescent growth velocity. It is particularly common in young athletes involved in jumping, sprinting and kicking sports — basketball, netball, football, athletics and gymnastics are the sports most frequently represented.
What causes it?
During adolescence the long bones grow rapidly from growth plates, and the surrounding tendons and muscles struggle to keep pace. At the inferior pole of the patella, the patellar tendon attaches to bone that is still developing and relatively soft compared to mature adult bone. Repeated powerful quadriceps contractions — from jumping, sprinting and kicking — create traction forces through the patellar tendon that exceed the developing apophysis's capacity to absorb, resulting in micro-damage, inflammation and pain at the attachment site.
Training load is a critical factor — SLJ most commonly develops during periods of increased sporting activity, at the start of a new season, or when a young athlete significantly increases their training volume. Rapid growth spurts that create a sudden mismatch between bone length and muscle-tendon unit length also increase vulnerability.
What are the symptoms?
The hallmark symptom is localised pain and tenderness at the bottom tip of the kneecap, typically provoked by activity — particularly jumping, landing, running and kneeling — and relieved by rest. The area may be visibly swollen and warm in more acute presentations. Stairs and squatting are commonly aggravating. The pain is typically worse after activity rather than during it in the early stages, progressing to pain during activity as the condition worsens if not managed.
Unlike some other causes of knee pain in teenagers, SLJ does not usually cause locking, giving way or significant swelling within the joint itself — if these symptoms are present, other diagnoses should be considered.
How is it diagnosed?
Diagnosis is clinical in most cases — a physiotherapist will identify the characteristic location of tenderness at the inferior patellar pole and reproduce symptoms with quadriceps loading tests. X-ray may show calcification or fragmentation at the inferior pole in established cases, though early presentations are often X-ray negative. Ultrasound can visualise the apophysis and confirm the diagnosis where there is doubt.
The age of the patient, the location of tenderness, the sporting history and the clinical examination findings together make the diagnosis straightforward in typical presentations.
Will it get better on its own?
Yes — Sinding-Larsen-Johansson syndrome is a self-limiting condition. It resolves when the growth plate closes and the apophysis matures into solid bone, which typically occurs by the mid-teenage years. The challenge is managing symptoms and maintaining sporting participation during the months to years before this happens.
Without management, the condition often becomes increasingly limiting — athletes who push through pain without modification frequently find their symptoms worsen to the point where they can't train at all. With appropriate physiotherapy, most young athletes can continue participating in modified sport throughout their recovery and return to full unrestricted activity once the apophysis has matured.
How can physiotherapy help?
Physiotherapy for SLJ focuses on reducing pain and inflammation during the acute phase, modifying load to allow continued participation at a tolerable level, and addressing the underlying factors — particularly quadriceps and hip strength, and lower limb biomechanics — that influence how much traction force is generated at the inferior patellar pole during activity.
Load management is the central intervention. Understanding the athlete's training schedule, competition calendar and overall physical load allows the physiotherapist to recommend specific modifications — reducing jump training volumes, temporarily substituting lower-impact conditioning, or adjusting game participation — that keep the athlete active without aggravating the apophysis.
Quadriceps flexibility — particularly of the rectus femoris — directly influences the traction load at the inferior patellar pole, and tight quadriceps are a consistent finding in adolescents with SLJ. Stretching and soft tissue work addressing rectus femoris and hip flexor flexibility is a routine part of the management program.
Patellar tendon taping or a patellar tendon strap can provide useful symptomatic relief during activity, offloading the inferior pole and allowing more comfortable participation in sport. Real time ultrasound can assist in assessing and retraining VMO activation where quadriceps inhibition from pain is affecting movement quality.
For young athletes in jumping or kicking sports, biomechanical assessment of landing technique, jump mechanics and running gait can identify patterns that increase inferior patellar pole loading — correcting these not only reduces current symptoms but also addresses injury risk more broadly.
Our page on physiotherapy for teenagers has more information on how we approach the adolescent athlete specifically, including how we involve parents and coaches in the management process. The Australian Physiotherapy Association has resources on adolescent sports injury for parents wanting to understand more about growth-related conditions.
Our physiotherapists Eliane Machado and Emma Cameron and exercise physiologist Ash O'Regan all have experience in adolescent knee conditions and sports injury management.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
Sinding-Larsen-Johansson syndrome (SLJ) is a growth-related condition affecting the knee in adolescents, characterised by pain and tenderness at the inferior pole of the patella (the bottom tip of the kneecap) — the point where the patellar tendon attaches to the patella. It occurs during periods of rapid growth when the bones are developing faster than the surrounding soft tissues can accommodate, creating traction stress at the developing apophysis (growth plate attachment) of the inferior pole.
It is sometimes confused with Osgood-Schlatter disease, which affects the tibial tuberosity — the bony bump just below the kneecap — rather than the kneecap itself. Both are growth-related traction apophysitis conditions and both are common in active adolescents, but the location of pain distinguishes them. SLJ pain is at the bottom of the kneecap; Osgood-Schlatter pain is lower, at the shin bone. Some teenagers have both simultaneously.
SLJ primarily affects boys aged 10 to 13 and girls aged 8 to 12 — the age range corresponding to peak adolescent growth velocity. It is particularly common in young athletes involved in jumping, sprinting and kicking sports — basketball, netball, football, athletics and gymnastics are the sports most frequently represented.
What causes it?
During adolescence the long bones grow rapidly from growth plates, and the surrounding tendons and muscles struggle to keep pace. At the inferior pole of the patella, the patellar tendon attaches to bone that is still developing and relatively soft compared to mature adult bone. Repeated powerful quadriceps contractions — from jumping, sprinting and kicking — create traction forces through the patellar tendon that exceed the developing apophysis's capacity to absorb, resulting in micro-damage, inflammation and pain at the attachment site.
Training load is a critical factor — SLJ most commonly develops during periods of increased sporting activity, at the start of a new season, or when a young athlete significantly increases their training volume. Rapid growth spurts that create a sudden mismatch between bone length and muscle-tendon unit length also increase vulnerability.
What are the symptoms?
The hallmark symptom is localised pain and tenderness at the bottom tip of the kneecap, typically provoked by activity — particularly jumping, landing, running and kneeling — and relieved by rest. The area may be visibly swollen and warm in more acute presentations. Stairs and squatting are commonly aggravating. The pain is typically worse after activity rather than during it in the early stages, progressing to pain during activity as the condition worsens if not managed.
Unlike some other causes of knee pain in teenagers, SLJ does not usually cause locking, giving way or significant swelling within the joint itself — if these symptoms are present, other diagnoses should be considered.
How is it diagnosed?
Diagnosis is clinical in most cases — a physiotherapist will identify the characteristic location of tenderness at the inferior patellar pole and reproduce symptoms with quadriceps loading tests. X-ray may show calcification or fragmentation at the inferior pole in established cases, though early presentations are often X-ray negative. Ultrasound can visualise the apophysis and confirm the diagnosis where there is doubt.
The age of the patient, the location of tenderness, the sporting history and the clinical examination findings together make the diagnosis straightforward in typical presentations.
Will it get better on its own?
Yes — Sinding-Larsen-Johansson syndrome is a self-limiting condition. It resolves when the growth plate closes and the apophysis matures into solid bone, which typically occurs by the mid-teenage years. The challenge is managing symptoms and maintaining sporting participation during the months to years before this happens.
Without management, the condition often becomes increasingly limiting — athletes who push through pain without modification frequently find their symptoms worsen to the point where they can't train at all. With appropriate physiotherapy, most young athletes can continue participating in modified sport throughout their recovery and return to full unrestricted activity once the apophysis has matured.
How can physiotherapy help?
Physiotherapy for SLJ focuses on reducing pain and inflammation during the acute phase, modifying load to allow continued participation at a tolerable level, and addressing the underlying factors — particularly quadriceps and hip strength, and lower limb biomechanics — that influence how much traction force is generated at the inferior patellar pole during activity.
Load management is the central intervention. Understanding the athlete's training schedule, competition calendar and overall physical load allows the physiotherapist to recommend specific modifications — reducing jump training volumes, temporarily substituting lower-impact conditioning, or adjusting game participation — that keep the athlete active without aggravating the apophysis.
Quadriceps flexibility — particularly of the rectus femoris — directly influences the traction load at the inferior patellar pole, and tight quadriceps are a consistent finding in adolescents with SLJ. Stretching and soft tissue work addressing rectus femoris and hip flexor flexibility is a routine part of the management program.
Patellar tendon taping or a patellar tendon strap can provide useful symptomatic relief during activity, offloading the inferior pole and allowing more comfortable participation in sport. Real time ultrasound can assist in assessing and retraining VMO activation where quadriceps inhibition from pain is affecting movement quality.
For young athletes in jumping or kicking sports, biomechanical assessment of landing technique, jump mechanics and running gait can identify patterns that increase inferior patellar pole loading — correcting these not only reduces current symptoms but also addresses injury risk more broadly.
Our page on physiotherapy for teenagers has more information on how we approach the adolescent athlete specifically, including how we involve parents and coaches in the management process. The Australian Physiotherapy Association has resources on adolescent sports injury for parents wanting to understand more about growth-related conditions.
Our physiotherapists Eliane Machado and Emma Cameron and exercise physiologist Ash O'Regan all have experience in adolescent knee conditions and sports injury management.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
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