Growth Plate Assessment

For Medical Students

What It Tests

In a skeletally immature knee the growth plate fails before the ligament does, so an injury that would tear an adult's ligament can separate a child's physis. 2.1.2 covers the distal femur.

The examination is deciding whether the tenderness sits over the physis or over the ligament, because those two findings lead to different places. 4.6.4 covers joint line tenderness.

It is a careful examination rather than a forceful one, since stressing a knee with an undisplaced physeal injury can displace it.

How It Is Performed

Establish the age, the stage of puberty and whether growth is continuing, since all three change what the findings mean. 4.19.6 covers developmental variants.

Take the mechanism and the ability to weightbear, because an inability to weightbear in a child is a stronger sign than in an adult. 4.2.20 covers a direct blow.

Inspect for swelling, deformity and the position the limb is held in. 4.3.1 covers observation from the door.

Palpate the physeal lines specifically: across the distal femur above the joint line and across the proximal tibia below it. 4.6.1 covers systematic palpation.

Palpate the ligament origins and insertions separately, so the tenderness can be assigned to one or the other. 4.12.4 covers the deep medial ligament.

Assess the range gently, and stop at the point of guarding rather than pushing through it. 4.7.6 covers the painful arc.

Defer stress testing until a radiograph has been seen if the physeal tenderness is convincing, and record that decision. 4.1.5 covers common examination pitfalls.

What a Positive Means

Tenderness across the physis rather than at the joint line indicates a physeal injury until a radiograph says otherwise, and it changes the examination.

Tenderness at the ligament insertion with a non tender physis points to a ligament injury, which is the less likely pattern in a young child. 4.12.4 covers the deep medial ligament.

An inability to weightbear with physeal tenderness and a normal radiograph is still a physeal injury, since an undisplaced separation may not show. 4.1.6 covers that relationship.

A knee held in flexion with a tense effusion after an injury needs urgent assessment rather than a complete examination. 4.8.7 covers the acute haemarthrosis.

A valgus stress producing opening in a child may be opening at the physis and not at the ligament, which is why the test is deferred. 4.12.1 covers valgus stress testing.

MRCS Level

How It Is Performed

In a viva this is the injured child's knee station and the expected answer puts the physis before the ligament.

The expected points are the age and maturity, the mechanism, the weightbearing status, the inspection, the separate palpation of physis and ligament, the gentle range, and the decision to defer stress testing.

Say that you would palpate the physeal lines as a named step, since that is the step that separates a paediatric from an adult examination. 4.6.1 covers systematic palpation.

Say that you would not apply a valgus or varus stress until the physis has been cleared, and give the reason. 4.12.1 covers valgus stress testing.

Say that you would assess the neurovascular status, because a displaced distal femoral physeal injury threatens the popliteal structures. 4.6.10 covers the popliteal fossa.

What a Positive Means

The reasoning expected is that the physis is cartilaginous and the ligament is collagenous, and under a valgus load in an immature knee the physis gives first. 2.1.2 covers the distal femur.

A physeal separation can be undisplaced and still unstable, which is why the clinical finding outweighs a normal radiograph. 4.1.6 covers that relationship.

Stress testing an undisplaced separation can displace it, and the displacement is the thing that causes the growth disturbance.

The distal femoral physis contributes a large share of lower limb growth, which is why an injury there matters more than its displacement suggests. 2.1.2 covers it.

How Good It Is

The examination localises tenderness reliably in a cooperative child and poorly in a distressed one.

Its most useful contribution is the decision to stop and image rather than to complete a stress examination, which is a judgement no imaging makes for it. 4.1.5 covers common examination pitfalls.

It is insensitive for an undisplaced physeal injury, which is why the threshold for imaging is low.

Radiographs show displacement and magnetic resonance imaging shows the physis, so the examination triggers the imaging rather than replacing it. 4.1.6 covers that relationship.

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 the examination of a growing knee establishes skeletal maturity, localises the injury and sets the urgency, and each of those changes the plan.

Skeletal maturity determines whether a physeal sparing approach is needed, and the clinical assessment of maturity starts the question that imaging answers. 4.19.2 covers the paediatric cruciate injury.

Localisation to the physis rather than the ligament changes the specialty, the imaging and the follow up, and the examination is where that happens. 4.6.1 covers systematic palpation.

A displaced physeal injury with a neurovascular deficit is an emergency, and the examination is what identifies it. 4.6.10 covers the popliteal fossa.

Growth remaining is recorded, because a physeal injury's consequence is proportional to it rather than to the injury's size. 2.1.2 covers the distal femur.

Where It Misleads

The commonest error is examining a child's knee as an adult's, so the physis is never palpated and a separation is called a ligament injury. 4.6.1 covers systematic palpation.

A distressed child guards everything, so the localisation that the examination depends on is unavailable and the examination overstates its own certainty.

A normal radiograph is read as excluding a physeal injury, which it does not. 4.1.6 covers that relationship.

Laxity found on stress testing is attributed to the ligament when the opening is at the physis. 4.12.1 covers valgus stress testing.

An apparently minor mechanism is discounted in a child, where the injury threshold is lower than in an adult. 4.2.20 covers a direct blow.

Fellowship Level

Where It Misleads

At fellowship level the examination of the growing knee has to estimate growth remaining, and it does that badly.

Chronological age, bone age and pubertal stage diverge, and the clinical assessment uses the two that are easiest to obtain rather than the one that matters. 4.19.6 covers developmental variants.

A knee examined after a physeal injury has healed can be entirely normal while a growth disturbance is developing, so the examination at follow up is about alignment and length rather than about the knee. 4.5.1 covers the mechanical axis.

A partial physeal arrest produces a progressive angular deformity, and the examination finding that detects it is an alignment change over time rather than any single measurement. 4.3.3 covers standing alignment.

Ligament injury and physeal injury coexist in the adolescent knee near maturity, and the examination tends to find one and stop. 4.19.2 covers the paediatric cruciate injury.

The examination cannot assess the physis itself, so every conclusion about it is an inference from the tenderness and the mechanism.