High Yield Overview

Radiological Signs in Paediatric Orthopaedics

DDH, SUFE, Perthes & Growth Plate Assessment

KleinLine tangent to femoral neck — fails to intersect epiphysis in SUFE

PerkinsVertical line from lateral acetabular edge for DDH assessment

HilgenreinerHorizontal line through triradiate cartilages for DDH

ShentonArc disruption in DDH and NOF fractures

SHSalter-Harris classification I-V for growth plate injuries

SALTRMnemonic for Salter-Harris types

USSPrimary modality for DDH before 6 months

HerringLateral pillar classification for Perthes prognosis

Paediatric Orthopaedic Imaging Signs

DDH: Hilgenreiner + Perkins lines, acetabular index, Shenton line, Graf USS

SUFE: Klein line, frog lateral (best view), Southwick angle

Perthes: Catterall classification, Herring lateral pillar, Gage sign, head-at-risk

Growth plate: Salter-Harris I-V (SALTR mnemonic)

NAI: Metaphyseal corner fractures, multiple fractures of different ages

Key: The Klein line for SUFE and Perkins/Hilgenreiner for DDH are the most tested paediatric signs

Critical Must-Knows

Klein line: a line drawn along the superior femoral neck on AP radiograph should intersect the lateral epiphysis. Failure = SUFE.
DDH assessment: Perkins line (vertical from lateral acetabular edge) and Hilgenreiner line (horizontal through triradiate cartilage) create four quadrants — femoral head should be in the inferomedial quadrant.
Salter-Harris classification (SALTR): Slip (I), Above (II), Lower (III), Through (IV), Rammed (V) — describes growth plate fracture pattern.
Perthes disease staging: Catterall classification (4 groups by extent of head involvement) and Herring lateral pillar classification (A, B, C by lateral pillar height preservation).
Ultrasound is the primary imaging modality for DDH screening before 6 months (Graf classification). AP pelvis radiograph after 6 months.

Examiner's Pearls

"
The Klein line is the single most important radiographic sign for SUFE — always check it on AP views of skeletally immature patients with hip or knee pain.
"
SUFE can present as knee pain (referred via the obturator nerve) — always examine and image the hip when a child presents with knee pain.
"
Perthes: the Herring lateral pillar classification is the best prognostic indicator. Group A (full height) = good prognosis. Group C (less than 50% height) = poor prognosis.
"
Salter-Harris Type II is the MOST COMMON growth plate fracture (75%). Type V may be radiographically occult — diagnosed retrospectively by growth arrest.
"
The metaphyseal corner fracture (bucket-handle) in an infant is highly specific for non-accidental injury (NAI).

Exam Warning

Paediatric radiological signs are among the most frequently tested topics. You must be able to: draw and interpret the Klein line (SUFE), construct Perkins and Hilgenreiner lines for DDH assessment, classify growth plate injuries using Salter-Harris, stage Perthes disease, and recognise the radiographic features of non-accidental injury. Classic traps: missing a mild SUFE by not drawing the Klein line, and not imaging the hips when a child presents with isolated knee pain.

Mnemonic

SALTRSalter-Harris Classification

Slip (Type I) — through the physis only

Fracture plane through the growth plate only. Radiograph may appear normal (widened physis is the only sign). Diagnosed clinically (tenderness at physis)

Above (Type II) — physis + metaphysis

Fracture through the physis with a metaphyseal fragment (Thurston-Holland fragment). MOST COMMON type (75%). Usually excellent prognosis

Lower (Type III) — physis + epiphysis

Fracture through the physis extending into the epiphysis (intra-articular). Requires anatomical reduction to restore articular surface and growth plate alignment

Through (Type IV) — physis + metaphysis + epiphysis

Fracture crosses all three zones. Most prone to growth disturbance (bone bridge formation). Requires ORIF for anatomical reduction

Rammed/cRush (Type V) — compression injury

Crush injury to the growth plate without visible fracture. Often diagnosed RETROSPECTIVELY when growth arrest becomes apparent. Worst prognosis for growth

Memory Hook:SALTR: Slip, Above, Lower, Through, Rammed — the five Salter-Harris types in order of increasing severity.

Mnemonic

PHASDDH Radiographic Assessment Lines

Perkins line (vertical)

Vertical line drawn from the lateral edge of the acetabulum, perpendicular to the Hilgenreiner line. The femoral head ossification centre should lie MEDIAL to this line

Hilgenreiner line (horizontal)

Horizontal line through both triradiate cartilages (Y-cartilage at the base of each acetabulum). The femoral head should lie BELOW and MEDIAL in the inferomedial quadrant

Acetabular index

Angle between the Hilgenreiner line and a line drawn from the triradiate cartilage to the lateral acetabular edge. Normal: less than 30 degrees at birth, decreasing with age. Increased = acetabular dysplasia

Shenton line (arc)

Smooth arc along the inferior border of the superior pubic ramus and medial femoral neck. DISRUPTED in DDH (hip subluxation/dislocation) and femoral neck fractures

Memory Hook:PHAS: Perkins, Hilgenreiner, Acetabular index, Shenton — the four lines/measurements for DDH assessment on AP pelvis.

Mnemonic

KISSSUFE Radiographic Assessment

Klein line (CRITICAL)

Line along superior femoral neck on AP view should intersect the lateral epiphysis. In SUFE: the epiphysis has slipped posteriorly and the line passes ABOVE the epiphysis (fails to intersect)

Ice cream falling off the cone

On the frog lateral view, the slipped epiphysis resembles ice cream sliding off a cone — the metaphysis (cone) is visible above the displaced epiphysis (ice cream)

Southwick angle for severity

Measured on the frog lateral view. Normal: approximately 12 degrees. Mild slip: less than 30 degrees. Moderate: 30-50 degrees. Severe: more than 50 degrees

Symmetry check (compare sides)

Always compare with the contralateral hip — bilateral SUFE occurs in 20-40% of cases. The Klein line should be assessed on BOTH sides

Memory Hook:KISS: Klein line, Ice cream sign, Southwick angle, Symmetry — the four components of SUFE radiographic assessment.

Overview

Radiological signs in paediatric orthopaedics are fundamental examination topics that test pattern recognition, understanding of growth plate anatomy, and knowledge of specific paediatric conditions. The key principle is that the developing skeleton has unique anatomical features (growth plates, ossification centres, developing joint morphology) that create both diagnostic challenges and specific pathological patterns not seen in adults.

Why Paediatric Imaging Is Different

The paediatric skeleton differs from the adult in: (1) Growth plates (physes) are cartilaginous and radiolucent — fractures through them may be invisible on radiographs (Salter-Harris I, V). (2) Ossification centres appear sequentially and can be confused with fractures (CRITOE in the elbow). (3) The periosteum is thicker and more metabolically active — greenstick and torus (buckle) fractures are unique to children. (4) Joints are more cartilaginous — ultrasound is needed before ossification occurs (DDH screening). (5) Remodelling potential is greater but depends on direction of angulation and proximity to the growth plate.

The Klein Line — Most Important Paediatric Sign

The Klein line is the single most important and most commonly tested radiographic sign in paediatric orthopaedics. HOW TO DRAW IT: on the AP pelvis or hip radiograph, draw a line along the superior cortex of the femoral neck and extend it laterally. In NORMAL hips, this line should intersect (cut through) the lateral portion of the femoral head epiphysis. In SUFE: the epiphysis has slipped posteriorly (and often inferiorly), so the Klein line passes ABOVE or TANGENTIAL to the epiphysis without intersecting it. ALWAYS CHECK BOTH SIDES. CRITICAL PITFALL: SUFE can present with isolated KNEE pain (referred pain via the obturator nerve). ALWAYS image the hips when assessing a child with atraumatic knee pain.

Clinical Imaging

Imaging Gallery

SUFE (SCFE) radiograph demonstrating Klein line and epiphyseal slip — Radiograph demonstrating slipped upper femoral epiphysis (SUFE/SCFE). The Klein line drawn along the superior femoral neck fails to intersect the lateral epiphysis on the affected side, while it normally intersects the epiphysis on the unaffected side. The frog lateral view (shown) demonstrates the 'ice cream falling off the cone' appearance.Credit: Open-i (NIH) (Open Access (CC BY))

DDH assessment using Perkins and Hilgenreiner lines schematic — Schematic demonstrating DDH assessment using Perkins (vertical) and Hilgenreiner (horizontal) lines on AP pelvis radiograph. The femoral head ossification centre should lie in the inferomedial quadrant formed by the intersection of these two lines. Displacement into the superolateral quadrant indicates subluxation or dislocation.Credit: Open-i (NIH) (Open Access (CC BY))

Systematic Approach

Paediatric Radiological Signs Assessment

Key Paediatric Conditions and Their Radiological Signs

Condition	Key Radiological Sign(s)	Clinical Significance
DDH (infants)	USS: Graf classification (alpha/beta angles). AP pelvis (more than 6mo): Perkins + Hilgenreiner lines, acetabular index, Shenton line	Femoral head in superolateral quadrant = subluxation/dislocation. Acetabular index more than 30 degrees = dysplasia
SUFE	Klein line fails to intersect epiphysis on AP. Frog lateral: ice cream off cone. Southwick angle for severity	Any positive Klein line = SUFE. Check BOTH sides (bilateral in 20-40%). Non-weight-bearing until surgical fixation
Perthes disease	Catterall: extent of head involvement (groups I-IV). Herring: lateral pillar height (A, B, C). Head-at-risk signs: Gage sign, lateral calcification	Herring A = good prognosis. Herring C = poor. Head-at-risk signs indicate need for containment treatment
Salter-Harris fractures	SALTR: I (physis only — may be normal radiograph), II (physis + metaphysis — most common), III (physis + epiphysis), IV (all three), V (crush — retrospective)	Type I: clinical diagnosis (tenderness at physis). Type III-IV: need anatomical reduction (ORIF). Type V: worst growth outcome
Non-accidental injury	Metaphyseal corner fractures (bucket-handle), multiple fractures of different ages, posterior rib fractures, complex skull fractures	Metaphyseal corner fractures in infants are HIGHLY SPECIFIC for NAI. Skeletal survey is mandatory
Congenital limb anomalies	Proximal femoral focal deficiency (PFFD), fibular hemimelia, limb length discrepancy	Aitken classification for PFFD. Scanogram for limb length. Planning for reconstruction or amputation

Detailed Condition Assessment

DDH Radiographic and Ultrasound Assessment

Before 6 months (ultrasound): The femoral head has not ossified, making radiographs unreliable. Ultrasound (hip USS) is the primary imaging modality. The Graf classification uses the alpha angle (bony acetabular coverage) and beta angle (cartilaginous coverage): Type I (normal): alpha more than 60 degrees. Type IIa (physiologically immature, under 3 months): alpha 50-59 degrees. Type IIb (delayed ossification, over 3 months — treat): alpha 50-59 degrees. Type III (subluxation): alpha less than 43 degrees. Type IV (dislocation): alpha less than 43 degrees, femoral head displaced.

After 6 months (radiograph): Four key assessments on AP pelvis radiograph (PHAS): (1) Perkins line (vertical from lateral acetabular rim) — femoral head ossification centre should be MEDIAL. (2) Hilgenreiner line (horizontal through triradiate cartilages) — femoral head should be INFERIOR. Together, these create four quadrants — the femoral head should be in the INFEROMEDIAL quadrant (any other location is abnormal). (3) Acetabular index — angle between Hilgenreiner line and the acetabular roof line. Normal: less than 30 degrees (decreases with age). More than 30 degrees = dysplastic. (4) Shenton line — smooth arc disrupted in subluxation/dislocation.

Additional DDH signs: Centre-edge angle of Wiberg (used in older children and adolescents): normal more than 25 degrees. Less than 20 degrees = dysplasia. Tonnis classification for acetabular coverage and subluxation grading in older patients.

Evidence Base

Herring Lateral Pillar Classification for Perthes

Prospective Multicentre Study

Herring JA, Kim HT, Browne R • Journal of Bone and Joint Surgery (American) (2004)

Key Findings:

Herring lateral pillar classification was the best predictor of outcome in Perthes disease.
Group A (full lateral pillar height): 94% had good or fair outcomes.
Group C (less than 50% lateral pillar height): only 38% had good outcomes.
Age at onset more than 8 years worsened prognosis within each Herring group.

Clinical Implication: The Herring classification, combined with age at onset, is the most reliable prognostic indicator for Perthes disease and guides treatment decisions.

Limitation: The classification can only be applied during the fragmentation stage — it cannot be assessed during the initial or healed stages.

Source: Herring JA et al. JBJS Am 2004;86(10):2121-34

Loder Stability Classification for SUFE

Prospective Study

Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD • Journal of Bone and Joint Surgery (American) (1993)

Key Findings:

Unstable SUFE (unable to weight-bear) had an AVN rate of 47%.
Stable SUFE (able to weight-bear) had an AVN rate of less than 5%.
Stability was a far stronger predictor of AVN risk than severity of slip angle.

Clinical Implication: The stability classification (ability to weight-bear) is the most important prognostic classification for SUFE — unstable slips have very high AVN risk regardless of treatment.

Limitation: Some patients cannot reliably communicate weight-bearing ability. Clinical assessment must be correlated with radiographic findings.

Source: Loder RT et al. JBJS Am 1993;75(8):1134-40

Graf Classification for DDH Ultrasound

Classification Study

Graf R • Archives of Orthopaedic and Trauma Surgery (1984)

Key Findings:

The alpha angle (bony coverage) reliably classified hip morphology: more than 60 degrees = normal (Type I).
Type IIa (physiological immaturity, alpha 50-59 degrees, under 3 months) resolved spontaneously in 95% of cases.
Types III and IV (subluxation/dislocation) required treatment to prevent long-term joint damage.

Clinical Implication: Graf USS classification provides standardised DDH assessment before the femoral head ossifies. Type I requires no treatment. Type IIb onwards requires intervention.

Limitation: Operator-dependent technique. Hips should be assessed in both coronal and transverse planes.

Source: Graf R. Arch Orthop Trauma Surg 1984;102(4):248-55

Salter-Harris Classification and Growth Disturbance

Retrospective Review

Peterson HA • Journal of Pediatric Orthopaedics (1994)

Key Findings:

Salter-Harris Type I and II had less than 2% risk of growth disturbance when anatomically reduced.
Type III had 10% growth disturbance risk, Type IV had 25%.
Type V crush injuries had the highest rate of growth arrest but were often diagnosed retrospectively.

Clinical Implication: Anatomical reduction of Type III-IV injuries minimises growth disturbance risk. Type V injuries may be radiographically occult and present later with growth arrest.

Limitation: Long-term follow-up is essential for ALL physeal injuries — growth arrest may not manifest for 6-18 months.

Source: Peterson HA. J Pediatr Orthop 1994;14(4):423-30

Metaphyseal Corner Fractures in NAI

Retrospective Study

Kleinman PK, Marks SC, Blackbourne B • Radiology (1986)

Key Findings:

Classic metaphyseal lesions (corner fractures/bucket-handle) were the most specific fracture pattern for non-accidental injury.
These fractures resulted from torsional and traction forces on the limb (shaking/yanking mechanism).
A skeletal survey was diagnostic in 79% of NAI cases, revealing additional occult fractures.

Clinical Implication: Metaphyseal corner fractures in infants are HIGHLY SPECIFIC for NAI and mandate full child protection investigation including skeletal survey.

Limitation: Not 100% specific — rare metabolic bone diseases can mimic these fractures. Requires multidisciplinary assessment.

Source: Kleinman PK et al. Radiology 1986;158(3):747-9

Australian Context

In Australia, paediatric orthopaedic imaging follows evidence-based guidelines established by the Royal Australasian College of Surgeons (RACS), Paediatric Orthopaedic Society of Australia (POSNA equivalent), and RANZCR. DDH screening follows the NHMRC selective ultrasound screening policy, with clinical hip examination at birth and 6-8 weeks, supplemented by ultrasound for at-risk infants.

SUFE management in Australia mandates urgent surgical fixation with in-situ pinning. Australian orthopaedic guidelines emphasise the importance of the Klein line assessment and the frog lateral view. Non-accidental injury reporting is mandatory in all Australian states and territories, and a skeletal survey is the standard radiographic investigation when NAI is suspected.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 12-year-old obese boy presents with a 3-week history of left knee pain. He walks with an antalgic gait. There is no history of trauma."

EXCEPTIONAL ANSWER

The most likely diagnosis is a SUFE (Slipped Upper Femoral Epiphysis). This classic presentation — an obese adolescent (10-16 years, during the growth spurt) with atraumatic hip or KNEE pain — should trigger immediate suspicion for SUFE. The CRITICAL teaching point is that SUFE commonly presents with KNEE pain due to referred pain via the obturator nerve. This is one of the most important pitfalls in paediatric orthopaedics — any child with unexplained knee pain MUST have the hip examined and imaged. The radiographic sign I would look for is the Klein line. On the AP pelvis radiograph, I would draw a line along the superior cortex of the femoral neck on both sides and extend it laterally. In a normal hip, this line intersects the lateral femoral head epiphysis. In SUFE: the epiphysis has slipped posteroinferiorly, so the line passes above or tangential to the epiphysis without intersecting it. I would compare both sides, because bilateral SUFE occurs in 20-40% of cases. I would also request a frog lateral view of both hips. This view shows the posterior slip most clearly — the 'ice cream falling off the cone' appearance. On the frog lateral, I would measure the Southwick angle to grade severity: mild (less than 30 degrees), moderate (30-50 degrees), severe (more than 50 degrees). I would classify the SUFE as stable (able to weight-bear) or unstable (unable to weight-bear) — this is the most important prognostic classification. Unstable SUFE has 47% AVN risk. Management: immediate non-weight-bearing (crutches or wheelchair), urgent orthopaedic referral for in-situ screw fixation. The contralateral hip should also be assessed for prophylactic fixation if risk factors are present (endocrine disorder, very young age, severe slip on the affected side).

KEY POINTS TO SCORE

SUFE presents with KNEE pain (referred via obturator nerve) — always image the hip

Klein line: line along superior femoral neck should intersect lateral epiphysis. Fails = SUFE

Frog lateral view shows posterior slip most clearly ('ice cream off cone')

Stable vs unstable classification: unstable = 47% AVN risk

Bilateral in 20-40% — always check BOTH sides

COMMON TRAPS

✗Not imaging the hip when a child presents with isolated knee pain

✗Not drawing the Klein line (subtle slips are easily missed)

✗Not requesting the frog lateral view (best view for SUFE)

✗Not assessing the contralateral hip

VIVA SCENARIOStandard

EXAMINER

"A 6-month-old infant is brought for DDH assessment. The paediatrician has noted asymmetric skin folds and limited left hip abduction."

EXCEPTIONAL ANSWER

At 6 months of age, the femoral head ossification centre is typically just beginning to appear. At this transitional age, BOTH ultrasound and radiograph may provide useful information, though radiograph becomes the standard modality after the femoral head ossification centre is clearly visible. I would request an AP pelvis radiograph as the primary investigation at this age. Radiographic assessment using PHAS: (1) PERKINS line — I draw a vertical line from the lateral edge of each acetabulum, perpendicular to the Hilgenreiner line. The femoral head ossification centre (or its expected position) should lie MEDIAL to this line. If the ossification centre is LATERAL to the Perkins line, this indicates lateral subluxation or dislocation. (2) HILGENREINER line — I draw a horizontal line through both triradiate cartilages. Combined with the Perkins line, this creates four quadrants. The femoral head should be in the INFEROMEDIAL quadrant. If it is in the superolateral quadrant, this represents subluxation or dislocation. (3) ACETABULAR INDEX — the angle between the Hilgenreiner line and a line from the triradiate cartilage to the lateral acetabular edge. At 6 months, normal is approximately 25-28 degrees. More than 30 degrees indicates acetabular dysplasia. I compare both sides. (4) SHENTON LINE — a smooth arc along the inferior border of the superior pubic ramus and the medial femoral neck. Disruption on the left side would confirm hip subluxation. Additional assessments: femoral head ossification centre — is it present bilaterally and symmetric? A delayed or smaller ossification centre on the affected side may indicate altered blood supply from the abnormal hip position. If DDH is confirmed: management at 6 months in Australia is typically a Pavlik harness trial (for stable reducible hips) or closed/open reduction under anaesthetic if the hip is irreducible. Follow-up imaging with serial radiographs to monitor acetabular development.

KEY POINTS TO SCORE

At 6 months, AP pelvis radiograph is the appropriate imaging modality

PHAS: Perkins (vertical), Hilgenreiner (horizontal), Acetabular index, Shenton line

Normal: femoral head in INFEROMEDIAL quadrant of Perkins/Hilgenreiner grid

Acetabular index more than 30 degrees = acetabular dysplasia

Disrupted Shenton line confirms subluxation/dislocation

COMMON TRAPS

✗Not knowing when to use USS vs radiograph (USS before 6 months, radiograph after)

✗Not drawing all four assessment lines (PHAS)

✗Not comparing both sides for symmetry

✗Not knowing the normal acetabular index values

VIVA SCENARIOChallenging

EXAMINER

"An examiner asks you to describe the Salter-Harris classification and its clinical implications."

EXCEPTIONAL ANSWER

The Salter-Harris classification describes five patterns of physeal (growth plate) fractures in children. It is clinically important because the type of fracture determines management (conservative vs surgical), prognosis for growth disturbance, and follow-up requirements. Type I (Slip — S): the fracture plane passes ENTIRELY through the physis (growth plate). There is no metaphyseal or epiphyseal fracture component. Radiographs may be NORMAL — the only finding may be widening of the physis. Diagnosis is often CLINICAL (point tenderness at the growth plate + inability to weight-bear/use the limb). Management: immobilisation. Growth disturbance risk is LOW (less than 2%). Type II (Above — A): the fracture passes through the physis and exits through the METAPHYSIS, creating a triangular metaphyseal fragment called the Thurston-Holland fragment. This is the MOST COMMON type (75% of all physeal fractures). The periosteum remains intact on the metaphyseal fragment side, acting as a hinge that aids reduction. Management: closed reduction and immobilisation. Growth disturbance risk is LOW (less than 2% if anatomically reduced). Type III (Lower — L): the fracture passes through the physis and extends into the EPIPHYSIS, creating an intra-articular fracture. This disrupts the articular surface. Management: anatomical reduction is ESSENTIAL for both articular congruity and growth plate alignment — often requires ORIF. Growth disturbance risk is MODERATE (approximately 10%). Type IV (Through — T): the fracture crosses ALL three zones — metaphysis, physis, and epiphysis. This creates the highest risk of bone bridge formation (bone growing across the damaged physis, tethering growth). Management: ORIF with anatomical reduction of both the articular surface and the growth plate. Growth disturbance risk is HIGH (approximately 25%). Type V (Rammed/Crush — R): a CRUSH injury to the growth plate without a visible fracture. This is the RAREST type and is often diagnosed RETROSPECTIVELY when growth arrest becomes apparent months later. The mechanism is characteristic of axial loading forces. Management: supportive. Prognosis: WORST for growth (crush injury destroys the germinal layer). Growth disturbance may result in angular deformity (partial growth arrest) or limb shortening (complete arrest).

KEY POINTS TO SCORE

SALTR mnemonic: Slip, Above, Lower, Through, Rammed

Type I may have NORMAL radiographs — diagnosed clinically (physis tenderness)

Type II is MOST COMMON (75%). Thurston-Holland fragment is the key finding

Types III-IV require ORIF for articular surface and growth plate alignment

Type V is diagnosed RETROSPECTIVELY — worst prognosis, crush mechanism

COMMON TRAPS

✗Not listing all five types and their distinguishing features

✗Not knowing that Type II is the most common (75%)

✗Not emphasising that Type V is often radiographically occult

✗Not knowing the growth disturbance rates for each type

Paediatric Radiological Signs — Exam Day Reference

High-Yield Exam Summary

DDH Assessment (PHAS)

•Perkins: vertical line from lateral acetabular edge
•Hilgenreiner: horizontal line through triradiate cartilages
•Together create 4 quadrants — femoral head should be INFEROMEDIAL
•Acetabular index: normal less than 30 degrees. More = dysplasia
•USS: before 6 months (Graf). Radiograph: after 6 months

SUFE Assessment (KISS)

•Klein line: along superior femoral neck — fails to intersect lateral epiphysis = SUFE
•Frog lateral: best view. Ice cream falling off cone appearance
•Southwick: mild (less than 30), mod (30-50), severe (more than 50 degrees)
•ALWAYS image hips for isolated knee pain in children
•Bilateral in 20-40%. Unstable = 47% AVN risk

Salter-Harris (SALTR)

•I (Slip): physis only — may be normal radiograph. Clinical diagnosis
•II (Above): physis + metaphysis — MOST COMMON (75%). Thurston-Holland fragment
•III (Lower): physis + epiphysis — intra-articular. ORIF for anatomical reduction
•IV (Through): all three zones — highest bone bridge risk. ORIF essential
•V (Rammed): crush — WORST prognosis. Diagnosed RETROSPECTIVELY

Perthes and NAI

•Herring lateral pillar: A (good), B (moderate), C (poor prognosis)
•Head-at-risk signs: Gage sign, lateral subluxation, lateral calcification
•NAI: metaphyseal corner fractures, posterior ribs, multiple ages
•NAI: skeletal survey MANDATORY. Mandatory reporting

Paediatric Radiological Signs Assessment

Key Paediatric Conditions and Their Radiological Signs

Condition	Key Radiological Sign(s)	Clinical Significance
DDH (infants)	USS: Graf classification (alpha/beta angles). AP pelvis (more than 6mo): Perkins + Hilgenreiner lines, acetabular index, Shenton line	Femoral head in superolateral quadrant = subluxation/dislocation. Acetabular index more than 30 degrees = dysplasia
SUFE	Klein line fails to intersect epiphysis on AP. Frog lateral: ice cream off cone. Southwick angle for severity	Any positive Klein line = SUFE. Check BOTH sides (bilateral in 20-40%). Non-weight-bearing until surgical fixation
Perthes disease	Catterall: extent of head involvement (groups I-IV). Herring: lateral pillar height (A, B, C). Head-at-risk signs: Gage sign, lateral calcification	Herring A = good prognosis. Herring C = poor. Head-at-risk signs indicate need for containment treatment
Salter-Harris fractures	SALTR: I (physis only — may be normal radiograph), II (physis + metaphysis — most common), III (physis + epiphysis), IV (all three), V (crush — retrospective)	Type I: clinical diagnosis (tenderness at physis). Type III-IV: need anatomical reduction (ORIF). Type V: worst growth outcome
Non-accidental injury	Metaphyseal corner fractures (bucket-handle), multiple fractures of different ages, posterior rib fractures, complex skull fractures	Metaphyseal corner fractures in infants are HIGHLY SPECIFIC for NAI. Skeletal survey is mandatory
Congenital limb anomalies	Proximal femoral focal deficiency (PFFD), fibular hemimelia, limb length discrepancy	Aitken classification for PFFD. Scanogram for limb length. Planning for reconstruction or amputation

DDH Radiographic and Ultrasound Assessment

Herring Lateral Pillar Classification for Perthes

Prospective Multicentre Study

Herring JA, Kim HT, Browne R • Journal of Bone and Joint Surgery (American) (2004)

Key Findings:

Herring lateral pillar classification was the best predictor of outcome in Perthes disease.
Group A (full lateral pillar height): 94% had good or fair outcomes.
Group C (less than 50% lateral pillar height): only 38% had good outcomes.
Age at onset more than 8 years worsened prognosis within each Herring group.

Clinical Implication: The Herring classification, combined with age at onset, is the most reliable prognostic indicator for Perthes disease and guides treatment decisions.

Limitation: The classification can only be applied during the fragmentation stage — it cannot be assessed during the initial or healed stages.

Source: Herring JA et al. JBJS Am 2004;86(10):2121-34

Loder Stability Classification for SUFE

Prospective Study

Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD • Journal of Bone and Joint Surgery (American) (1993)

Key Findings:

Unstable SUFE (unable to weight-bear) had an AVN rate of 47%.
Stable SUFE (able to weight-bear) had an AVN rate of less than 5%.
Stability was a far stronger predictor of AVN risk than severity of slip angle.

Limitation: Some patients cannot reliably communicate weight-bearing ability. Clinical assessment must be correlated with radiographic findings.

Source: Loder RT et al. JBJS Am 1993;75(8):1134-40

Graf Classification for DDH Ultrasound

Classification Study

Graf R • Archives of Orthopaedic and Trauma Surgery (1984)

Key Findings:

The alpha angle (bony coverage) reliably classified hip morphology: more than 60 degrees = normal (Type I).
Type IIa (physiological immaturity, alpha 50-59 degrees, under 3 months) resolved spontaneously in 95% of cases.
Types III and IV (subluxation/dislocation) required treatment to prevent long-term joint damage.

Clinical Implication: Graf USS classification provides standardised DDH assessment before the femoral head ossifies. Type I requires no treatment. Type IIb onwards requires intervention.

Limitation: Operator-dependent technique. Hips should be assessed in both coronal and transverse planes.

Source: Graf R. Arch Orthop Trauma Surg 1984;102(4):248-55

Salter-Harris Classification and Growth Disturbance

Retrospective Review

Peterson HA • Journal of Pediatric Orthopaedics (1994)

Key Findings:

Salter-Harris Type I and II had less than 2% risk of growth disturbance when anatomically reduced.
Type III had 10% growth disturbance risk, Type IV had 25%.
Type V crush injuries had the highest rate of growth arrest but were often diagnosed retrospectively.

Clinical Implication: Anatomical reduction of Type III-IV injuries minimises growth disturbance risk. Type V injuries may be radiographically occult and present later with growth arrest.

Limitation: Long-term follow-up is essential for ALL physeal injuries — growth arrest may not manifest for 6-18 months.

Source: Peterson HA. J Pediatr Orthop 1994;14(4):423-30

Metaphyseal Corner Fractures in NAI

Retrospective Study

Kleinman PK, Marks SC, Blackbourne B • Radiology (1986)

Key Findings:

Classic metaphyseal lesions (corner fractures/bucket-handle) were the most specific fracture pattern for non-accidental injury.
These fractures resulted from torsional and traction forces on the limb (shaking/yanking mechanism).
A skeletal survey was diagnostic in 79% of NAI cases, revealing additional occult fractures.

Clinical Implication: Metaphyseal corner fractures in infants are HIGHLY SPECIFIC for NAI and mandate full child protection investigation including skeletal survey.

Limitation: Not 100% specific — rare metabolic bone diseases can mimic these fractures. Requires multidisciplinary assessment.

Source: Kleinman PK et al. Radiology 1986;158(3):747-9