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1 · SNAPSHOT

Sinding-Larsen-Johansson Syndrome (Inferior Pole Apophysitis) body chart — Illustrative, not diagnostic. Canva body chart for Sinding-Larsen-Johansson Syndrome (Inferior Pole Apophysitis).

Who: Adolescents in growth spurts. Jumping, sprinting and kicking sports.
What: Traction apophysitis at the inferior pole of the patella.
How it behaves: Gradual anterior knee pain. Worse with stairs, squats, jumping. Point tenderness on the inferior pole.

The one thing to take from this page:

Same site, two very different things. Gradual with full active extension is apophysitis. Acute, with an extensor lag or an inability to straight-leg raise, is a sleeve fracture until imaging says otherwise.

Same site, two stories

Fits SLJ	Fits patellar sleeve fracture
Gradual onset over weeks	Acute, during a jump or kick
Load-related, settles with rest	Immediate functional loss
Full active extension	Extensor lag, or can't straight-leg raise
Local tenderness, no effusion	Major swelling, can't weight bear
Deload and reload	Image. Orthopaedic review

⚠️ There is no clinical guideline for this condition, only a hospital pre-referral note that borrows Osgood-Schlatter management, and no trial evidence for treating it. The management below is imported from Osgood-Schlatter, where the cohort evidence actually sits. That is stated, not hidden.

2 · SE — THE SUBJECTIVE PATTERN (the 70%)

Five stages, in your course's order. The whole subjective is built around one question: is this gradual or is this acute?

MAIN PROBLEM

"It hurts right on the point of my kneecap when I jump."
"Stairs and squats set it off."
"It came on over a few weeks."

BODY CHART

One finger, on the inferior pole of the patella.
Mark the tibial tuberosity separately. That is Osgood-Schlatter, and both can coexist.
Diffuse peri-patellar? Patellofemoral pain.
Mid-tendon in a skeletally mature athlete? Patellar tendinopathy.

BEHAVIOUR

	Fits SLJ	Points elsewhere
Aggs	Jumping, kicking, sprinting, stairs, squats	Prolonged sitting, diffuse → PFP
Severity	VAS 0–10 at best / at worst / right now	—
Onset	Gradual, over weeks, tracking load and growth	Acute, during a single jump → sleeve fracture
Extension	Full active extension	Extensor lag, can't SLR → sleeve fracture
Swelling	Local, minor	Major swelling, can't weight bear → escalate
Night	Sore after activity	Night or rest pain → screen

HISTORY

Gradual or sudden? Ask it directly and do not accept "a few weeks" without checking whether something happened in between.
Growth spurt? Ask the parent.
Sport, volume, recent change, number of teams.
Any moment where it changed suddenly? A sleeve avulsion has been documented occurring in an adolescent who already had SLJ [1]. A known diagnosis does not protect them from the new one.

SPECIAL / SCREENING QUESTIONS

Can they straight-leg raise? Ask before you examine, then check it.
Night pain, rest pain, fever, weight loss? Adolescent, bone pain — ask every time.
Any locking, giving way, or true effusion?
Hip or groin pain, or a limp? SCFE and Perthes present as knee pain.

Assessing this region? Download the Knee assessment template →

3 · HYPOTHESIS RANKING

Competing pattern	The one discriminating feature
Osgood-Schlatter disease	Tenderness and swelling at the tibial tuberosity rather than the inferior pole. Often coexists.
Patellar tendinopathy	Skeletally mature. Same site, tendon rather than apophysis, positive decline squat.
Patellofemoral pain	Diffuse rather than point tenderness, poor hip-knee control on step-down.
Bipartite patella and other non-traumatic patellar appearances	An imaging finding that mimics pathology — the paediatric patella has several [2].
Referred hip pathology	Screen the hip in every adolescent knee. SCFE and Perthes present here.

The one that outranks everything on this page

Patellar sleeve fracture. Same site, same age group, completely different pathway. A comparative radiographic study exists precisely because separating paediatric patellar sleeve fractures from SLJ and other inferior-pole pathologies is a recognised clinical problem [3], and the case literature runs in both directions: acute SLJ mimicking a sleeve fracture [4], and a sleeve avulsion occurring in a patient with SLJ (Schmidt-Hebbel et al. 2020), including a minimally displaced one [5].

Minimally displaced is the trap. It is the version that looks like an unusually bad flare-up.

And the rest of the differential in an adolescent

Night pain, rest pain or systemic symptoms move you off this page entirely [6].

4 · RED FLAGS — DON'T MISS THIS

This section is free, on every pattern, forever. Safety is never gated.

Finding	What it suggests	What you do
Extensor lag, or can't straight-leg raise	Patellar sleeve fracture	Image. Orthopaedic review
Acute onset during a jump or kick	Sleeve fracture, avulsion	Image
Major swelling or a true effusion	Fracture, intra-articular injury	Image
Inability to weight bear	Fracture	Image
A palpable gap or high-riding patella	Extensor mechanism disruption	Urgent orthopaedic review
Night pain or pain at rest	Bone tumour, infection	Image. Medical review
Fever, unwell, weight loss	Infection, systemic disease	Medical review, same day
Limp with hip or groin pain	SCFE, Perthes	Image the hip. Urgent

The rule: gradual inferior-pole pain with full active extension and a clean systemic screen is yours. An extensor lag, an acute onset, or an inability to straight-leg raise is a sleeve fracture until imaging says otherwise.

Cross-links: Osgood-Schlatter disease · Patellofemoral pain · Sever's disease

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Guideline anchor

No Australian guideline covers Sinding-Larsen-Johansson syndrome, and no clinical guideline of any nationality does: a Perth Children's Hospital pre-referral note names it, but only borrows Osgood-Schlatter management.

Anchored to the scoping review of the condition (Wilczyński et al. 2024, PMID 39346060) for what is and isn't known, to the comparative radiographic study separating paediatric patellar sleeve fractures from inferior-pole pathologies (Devana et al. 2022, PMID 35142232) for the safety branch, and to the paediatric knee-pain review (Kuwabara et al. 2021, PMID 33818701) for the differential.

PubMed Source

There is no clinical guideline here. The evidence base is a scoping review, imaging reviews, a comparative radiographic study and a large number of case reports — the scoping review itself is the acknowledgement that the literature is thin. Management on this page is imported from the better-studied sibling pattern, Osgood-Schlatter, and that import is stated rather than hidden.

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The evidence summary is for members

Verified diagnostic accuracy, where the evidence stands and what it doesn't settle. Free with an account.

Sources · 17

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Every source on this page resolves and title-verifies against PubMed. Newest first.

2020Schmidt-Hebbel et al. (2020). Patellar sleeve avulsion fracture in a patient with Sinding-Larsen-Johansson syndrome: a case report. BMC musculoskeletal disorders, 21(1), 267. https://doi.org/10.1186/s12891-020-03297-z
2024Masroori et al. (2024). Patellar Non-Traumatic Pathologies: A Pictorial Review of Radiologic Findings. Diagnostics (Basel, Switzerland), 14(24). https://doi.org/10.3390/diagnostics14242828
2022Devana et al. (2022). Clinical and Radiographic Differentiation of Pediatric Patellar Sleeve Fractures and Other Inferior Pole Pathologies. The American journal of sports medicine, 50(4), 977-983. https://doi.org/10.1177/03635465221073995
2018Alassaf (2018). Acute presentation of Sinding-Larsen-Johansson disease simulating patella sleeve fracture: A case report. SAGE open medical case reports, 6, 2050313X18799242. https://doi.org/10.1177/2050313X18799242
2023Negrão et al. (2023). Sinding-Larsen-Johansson syndrome with minimally displaced patellar sleeve avulsion fracture: a case report with multimodality approach and literature review. Skeletal radiology, 52(7), 1403-1407. https://doi.org/10.1007/s00256-022-04237-9
2021Kuwabara et al. (2021). Narrative Review - Knee Pain in the Pediatric Athlete. Current reviews in musculoskeletal medicine, 14(3), 239-245. https://doi.org/10.1007/s12178-021-09708-5
2009Iwamoto et al. (2009). Radiographic abnormalities of the inferior pole of the patella in juvenile athletes. The Keio journal of medicine, 58(1), 50-3. https://doi.org/10.2302/kjm.58.50
1989De Flaviis et al. (1989). Ultrasonic diagnosis of Osgood-Schlatter and Sinding-Larsen-Johansson diseases of the knee. Skeletal radiology, 18(3), 193-7. https://doi.org/10.1007/BF00360969
2008Draghi et al. (2008). Overload syndromes of the knee in adolescents: Sonographic findings. Journal of ultrasound, 11(4), 151-7. https://doi.org/10.1016/j.jus.2008.09.001
2012Valentino et al. (2012). Sinding-Larsen-Johansson syndrome: A case report. Journal of ultrasound, 15(2), 127-9. https://doi.org/10.1016/j.jus.2012.03.001
2024Yaya-Quezada et al. (2024). Imaging of the Pediatric Knee. Seminars in musculoskeletal radiology, 28(4), 462-476. https://doi.org/10.1055/s-0044-1786152
2010Nath & Lattin GE (2010). Patellar sleeve fracture. Pediatric radiology, 40 Suppl 1, S53. https://doi.org/10.1007/s00247-010-1721-8
2014Sullivan et al. (2014). Patellar sleeve fracture. The western journal of emergency medicine, 15(7), 883-4. https://doi.org/10.5811/westjem.2014.8.22265
2026Wedderkopp et al. (2026). Incidence of and Risk Factors for Lower Extremity Apophysitis in Children and Adolescents. Sports medicine (Auckland, N.Z.), 56(3), 793-803. https://doi.org/10.1007/s40279-025-02328-w
2025Alhamzah et al. (2025). Beyond conservative management: Surgical excision for symptomatic Sinding-Larsen-Johansson syndrome: A case report and literature review. Medicine, 104(52), e46792. https://doi.org/10.1097/MD.0000000000046792
2019Malherbe (2019). Traction apophysitis of the knee: A case report. Radiology case reports, 14(1), 18-21. https://doi.org/10.1016/j.radcr.2018.09.012
2024Wilczyński et al. (2024). Sinding-Larsen-Johansson disease. Clinical features, imaging findings, conservative treatments and research perspectives: a scoping review. PeerJ, 12, e17996. https://doi.org/10.7717/peerj.17996

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