Sinding-Larsen-Johansson Syndrome

For Medical Students

What It Tests

This is a traction apophysitis at the lower pole of the patella, where the patellar tendon takes its origin from a growth centre that has not yet fused. 2.4.2 covers ossification.

It is the same mechanism as the tubercle condition, at the other end of the same tendon, and the two are separated by where the tenderness sits. 4.16.4 covers the tubercle version.

Examining for it means localising tenderness to the lower pole of the patella in a growing patient with a normal joint. 4.6.5 covers patellar tenderness.

How It Is Performed

Establish the patient's skeletal maturity from their age and growth history. 4.19.1 covers that assessment.

Palpate the lower pole of the patella directly, with the knee extended and relaxed, noting focal tenderness there.

Palpate the tubercle as well, and note which of the two is more tender, since that is the discriminator. 4.6.7 covers the tubercle.

Palpate the tendon's mid substance, which should be less tender than either end.

Assess the range and look for an effusion, both of which should be normal. 4.6.3 covers the effusion assessment.

Ask about the activity pattern, since this is an overload condition in an active child. 4.2.11 covers aggravating factors.

What a Positive Means

Focal tenderness at the lower pole of the patella in a growing patient, with a normal joint and an activity related pattern, is the characteristic picture.

Tenderness at the tubercle instead points at the other condition, and the two can coexist. 4.16.4 covers it.

An effusion, night pain or a limited range points away from this diagnosis entirely and should be pursued. 4.8.2 covers the effusion's significance.

The adult equivalent at this site is tendinopathy at the tendon's origin, and the skeletal maturity is what separates them. 4.16.3 covers it.

Bilateral symptoms are common and are not a reason to doubt the diagnosis.

MRCS Level

How It Is Performed

In a viva this condition is usually offered as a contrast with the tubercle one, and naming the discriminator is the mark.

The expected points are the skeletal maturity, the focal tenderness at the lower pole, the comparison with the tubercle, the normal joint, and the activity pattern.

Say that the position of the tenderness is the diagnosis, since the mechanism and the management are otherwise the same. 4.16.4 covers the other end.

Say what would change your mind, because an effusion or night pain in a growing knee is a different and more serious problem. 4.19.1 covers that group.

Say that the diagnosis is clinical and self limiting, which is the reassurance the family needs.

What a Positive Means

The reasoning expected is that in a growing skeleton the apophysis at either end of the tendon is weaker than the tendon itself, so traction injures the growth centre rather than the tendon. 2.4.2 covers ossification.

The patella's lower pole ossifies last, which is why it is vulnerable in the years before maturity and why the condition has an age range. 2.4.1 covers the patellar anatomy.

The same eccentric loading in jumping and sprinting that produces tendinopathy in an adult produces this in a child, which is why the activity history is the same. 4.16.3 covers the adult version.

Fusion at maturity resolves it, which is why the prognosis is good and the treatment is time and load modification.

How Good It Is

The clinical diagnosis is reliable in a growing patient with focal lower pole tenderness and a normal joint.

Its reliability depends on the joint being normal, and an effusion or a limited range makes the diagnosis unsafe. 4.6.3 covers that assessment.

Radiographs exclude the serious alternatives rather than confirming this, and that negative is their role. 4.1.6 covers the relationship.

It cannot be distinguished from early tendinopathy at the same site in a patient near maturity, and in that group the distinction matters less than it sounds, because the management is similar. 4.16.3 covers it.

No figures appear for any accuracy comparison on this page, under decision 023, and the comparison is the claim being made.

FRCS Level

How Good It Is

At decision level this is a reassurance and a filter, as the tubercle condition is, and the surgical content is in what it is not.

A growing patient with the characteristic findings needs explanation, load modification and time.

A patient with an effusion, night pain, rest pain or a limited range is a different problem, and the differential in a growing knee includes infection and a bone tumour. 4.19.1 covers that group.

A patient near maturity with persistent symptoms is moving towards the adult tendinopathy, and the management continues rather than changing. 4.16.3 covers it.

A separate ossicle persisting after maturity, with focal pain, is the one situation in which a procedure is occasionally discussed, and the imaging rather than the examination establishes it. 4.1.6 covers that relationship.

Where It Misleads

The commonest error is not distinguishing it from the tubercle condition, which is a matter of where you palpate.

The second is accepting the diagnosis in a knee with an effusion or night pain.

The third is over investigating a clinically clear case.

The fourth is implying it will resolve quickly, when it resolves with maturity.

The fifth is treating it with rest alone when load modification works better and keeps a child active. 4.4.10 covers screening.

Fellowship Level

Where It Misleads

In referred practice this condition arrives either as a correct diagnosis needing reassurance or as a label on a knee that was not examined carefully.

A growing patient with anterior pain, a normal joint and tenderness at the lower pole has this, and the referral usually needs explanation rather than investigation. 4.6.5 covers the palpation.

A patient with persistent pain after maturity and a separate ossicle has a mechanical residue, and that is a different conversation from an apophysitis.

A patient with bilateral symptoms, systemic features and several tender insertions has an enthesopathy rather than an overload condition, and the specialty changes. 4.2.14 covers inflammatory pain.

An adolescent athlete whose symptoms recur each season has a load pattern problem rather than a recurring disease, and the proximal and landing assessments are where the modifiable part is. 4.4.9 covers single leg landing.

In medicolegal work this is a developmental condition and is not attributable to an injury, which is the same clear statement as at the tubercle. 4.23.7 covers that setting.