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Legg-Calvé-Perthes Disease

- Clinical and Radiologic Manifestation -

부산대학교병원 정형외과

김 휘 택

INTRODUCTION

1. LCP disease is an idiopathic osteonecrosis of the

capital femoral epiphysis in children

2. Etiology and management represent a challenge to

orthopaedists

3. It is a significant source of disability in children

EPIDEMIOLOY

1. Common from ages 4 to 8

2. 80% or more of patients are boys (boys : girls =

4 or 5 : 1)

3. 10 to 12% of the patients have bilateral

involvement

4. More common in Asians, Central Europeans

(unusual in blacks, and native Americans)

ETIOLOGY

1. Traditional concept: trauma and inflammation

2. Most current theories concern some disruption of

vascular system

3. Recent research: disorders of clotting system

: Thrombophilia (thrombotic venous occlusion)

- Deficiencies in protein C or S, or resistance to activated

protein C

- Factor-V Leiden mutation and anticardiolipin antibodies

Etiology

4. Systemic factors

1) Delayed skeletal maturity (by about 21 months), but

recovery is possible during later growth

2) Low level of somatomedin C insulin-like growth

factor-1 (IGF1)

3) Hyperactivity or attention deficit disorder

4) Hereditary influences (genetic component)

5) Environmental influences: high occurrence in

particular urban areas (in lower socioeconomic status)

“Unifying“ hypothesis Etiology

Hyperactive child

Minor trauma

Tendency to form clots

Abnormality of

the clot-lysing system

Clotting

in the venous system Venous pressure

rises in the femoral neck

Clotting propagates into

the femoral head

Infarction occurs

1

2

3

4

5

6

7

1. Painless limping – usually first noticed by a

parent

2. Pain in the groin, anterior thigh, or knee

CLINICAL PRESENTATION

PHYSICAL EXAMINATION

1. LOM - primarily IR and ABD

(flexion/extension less affected)

2. Positive Trendelenburg test (thigh, calf,

buttock atrophy)

3. Hip flexion contracture

4. Leg length inequality:

a) adduction contracture

b) collapse of capital femoral epiphysis

• Diagnosis

• Staging

• Provide prognosis

• Follow the course of the disease

• Assess results

1. Radiography: (primary tool )

IMAGING STUDY

Modified Waldenström classification:

(radiographic staging of disease evolution)

1. Initial (AVN) stage

2. Fragmentation stage

3. Reossification (healing) stage

4. Residual stage

Image studies – x-ray

• Widening of the medial joint space (synovitis & hypertrophy of articular cartilage)

• Smaller ossific nucleus (cessation of growth of the capital epiphysis)

1. Initial stage

• Lateralization of the femoral head

• Subchondral fracture

(Waldenström’s sign)

• Metaphyseal lucencies

• Increased density of the femoral

head (accumulation of new bone

on the dead bone trabeculae in the

head

2. Fragmentation stage 3. Reossification stage

4. Residual stage

Gradual remodeling of head shape:

• until skeletal maturity

• acetabulum also remodels

Other radiographic findings

Metaphyseal cyst or lucency (during active disease)

• Poor prognostic value

→ physeal cartilage

extending into the

metaphysis

→ true cyst within the

epiphysis or physis,

metaphysis

Image studies – x-ray

• Radiodense line

overlying the

proximal femoral

metaphysis

• Anterolateral-

inferior protruded

portion of the

femoral head

Image studies – x-ray

“Sagging rope” sign (during healing stage)

• Lateral extrusion of the

capital nucleus

- mushroom head

• Premature physeal

closure with greater

trochanteric overgrowth

Changes in the physis

Image studies – x-ray

Scintigraphy

• Tc 99m bone scan

• Periodic bone scans:

useful for prognosis & to

follow the course of the

disease

Image studies

Arthrography

• Assess the congruity of the

hip in many different

positions

• Most often used in the

early diagnosis of hinge

abduction

Image studies

MRI

• Early Dx.

• Configuration of the

femoral head and

acetabulum

• Revascularization

• Hinge abduction

Image studies

Hinge abduction

Computed tomography

• Not typically used

• Demonstrate 3D images

of the shape of the

femoral head and

acetabulum

Image studies

CLASSIFICATION SYSTEMS (Based on severity of disease)

1. Catterall classification

2. Salter-Thompson classification

3. Lateral pillar classification

An accurate, reliable, and reproducible

classification system is particularly important

in a disorder as variable as LCP.

Group I Group II

Group III Group IV

No metaphyseal reaction No sequestrum No subchondral fracture line

Sequestrum present – junction clear Metaphyseal reaction – antero/lateral Subchondral fracture line – anterior half

Sequestrum – large – junction sclerotic Metaphyseal reaction – diffuse antero/lateral Subchondral fracture line – posterior half

Whole head involvement Metaphyseal reaction – central or diffuse Posterior remodelling

Catterall classification

Catterall classification • Amount of CFE involvement / during the fragmentation stage

Classification

Group I Group II Group III Group IV

CFE

involvement Ant. 25% Up to 50% Up to 75% Entire

Subchondral

Fx. line

No Ant. 1/2 Post. 1/2 Post. margin

Sequestrum No Present

Large

Whole head

Metaphyseal

reaction No Anterolateral Diffuse

anterolateral Central or

diffuse

• Disadvantage

- High degree of interobserver variability

- Not applicable as a therapeutic guide for average of

8 months after onset

Classification

Catterall classification

Salter-Thompson classification

• Based on the extent of the subchondral fracture (initial)

• Group A - less than 50% of the femoral head (good Px)

Group B - more than 50% of the femoral head (poor Px)

Classification

Salter-Thompson classification

• Advantage - good interobserver reliability &

can be applied early in the course of disease

• Disadvantage - not all patients are diagnosed early during

the phase of the subchondral fracture

Classification

Lateral pillar classification

Classification

• Based on the height of the lateral pillar

on an AP view (early fragmentation

stage)

• Intact lateral pillar acts as a weight

bearing support to protect the central

avascular segment

Pillar A

Pillar B

Pillar C

• height maintained

• narrow pillar (2-3 mm)

• little ossification

Pillar B/C border • 50% height

• no collapse of central part

• depressed relative to central pillar

• 50% height

• minimal density of lat. pillar

Herring JA, Kim HT and Browne R:

JBJS Am, 86:2103-2120, 2004.

Lateral pillar classification

Classification

No involvement of the lateral pillar (the best outcome)

Lateral pillar maintains at least 50% of its height

(intermediate outcome)

a) a very narrow pillar (2-3 mm wide) that is >50% of the

original height

b) a lateral pillar with very little ossification but with at least

50% of the original height

c) a lateral pillar with exactly 50% of the original height that

is depressed relative to the central pillar

A loss of more than 50% of the original height of the lateral

pillar (the worst outcome)

Group A

Group B

Group C

Group B/C

border

(new)

PATHOGENESIS OF DEFORMITY

1. Growth disturbance in the CFE and physis

2. Related to the disease process

3. Repair process itself

4. Iatrogenic

LCPD-Pathogenesis of deformity

1

2

3

4

5

1. Growth disturbance in the CFE and physis

Patho. - deformity

Growth plate closure

Hinge abduction • Central arrest

→ short neck (coxa breva)

with trochanteric overgrowth

• Lateral arrest

→ tilts the head externally and

into valgus with trochanteric

overgrowth

2. Related to the disease process

• Superficial layers of articular cartilage:

“overgrow” as they are nourished by the synovial fluid

• Deeper layers : devitalized by the disease process

→ collapse (epiphyseal trabecula) and deformity

Patho. - deformity

3. Repair process itself

• The applied stresses on the femoral head

• Molding action of the acetabulum on the femoral

head

• Deformed femoral head may deform the acetabulum

Patho. - deformity

4. Iatrogenic

• Caused by trying to contain

a non-containable femoral

head (either non-surgically

or surgically)

Patho. - deformity

CLINICAL COURSE (1) 1. Moderate symptoms for 12 to 18 months

2. Starting with early synovitis and/or avascularity with limp

or stiffness of the hip

3. Subchondral bone fracture initiates reactive synovitis,

limiting mobility

4. Muscle spasm (especially, adductors) and weight bearing on

the diseased femoral head cause further subchondral

collapse (femoral head deformity, flattening, and

subluxation)

CLINICAL COURSE (2) 5. Vascular regeneration (creeping substitution) reossifies

the femoral head (often results in hypertrophy)

6. Poorest results are seen in hips with the greatest degree

of involvement

7. Age: before 6 years (mild disease), from 6 to 9 (moderate),

9 or older (the most severe course and worst outcome)

8. Duration: the longer it takes for the hip to heal, the lower

the chance for a good outcome

DIFFERENTIAL DIAGNOSIS

Bilateral changes Unilateral changes

Hypothyroidism Infectious (inflammatory) Ds

Spondyloepiphyseal dysplasia Gauchers Ds

Multiple epiphyseal dysplasia Eosinophilic granuloma

Pseudoachondroplasia Lymphoma

Hemophilia

Bilateral LCP

(Lt. 1.5 years after Rt.)

PROGNOSTIC FACTORS

1) Deformity of the femoral head (hip joint incongruity –

Stulberg classification): the most important prognostic

factor

2) Age at onset of disease: second most significant factor

(whether “older” means older than 6 years, or older than

8 years is subject to debate)

1. Described in Lowell & Winter’s book

Prognostic factors

3) Extent of epiphyseal involvement (the classifications

of Catterall, Salter-Thompson, and Herring)

4) Growth disturbance secondary to premature physeal

closure

5) Protracted course of disease

6) Remodeling potential

7) Type of treatment (?)

8) Stage at initiation of treatment

1) Gage’s sign: a radiolucent V-shaped defect in the

lateral epiphysis and metaphysis

2) Calcification lateral to the epiphysis

3) Metaphyseal lesions

4) Lateral subluxation of the femoral head

5) Horizontal growth plate

2. Radiographic head-at-risk signs (Catterall):

(Causing unexpected poor results)

Prognostic factors

1

1

1. Gage sign: a V-shaped defect

• Deformed FH

• Reversible with Tx

2

2. Lateral

calcification

• Early ossification

• Deformed FH

• Reversible with Tx

2

3

2. calcification

3. metaphyseal change

3. Herald the potential

for growth disturbance

of the physeal plate

2

2

3

2. calcification

3. metaphyseal change

4

5

4. subluxation

5. horizontal

growth plate

4. Widened head

5. Head deformity → hinge abduction

1) Catterall groups III and IV

2) Salter-Thompson group B

3) Lateral pillar group C

4) Lateral pillar group B (> 8 years old)

3. Hips at risk for a poor prognosis

Prognostic factors

4. Clinical at-risk factors

1) Older child

2) Obesity

3) Female sex

4) Marked LOM

Prognostic factors

ANALYSIS OF LATE FEMORAL HEAD DEFOMITIES

functional coxa vara

“sagging rope” sign 변형된 대퇴골두의

전방-하방-외측연에 해당된다.

LCPD-Imaging study (3DCT)

groove on femoral head

Rt. femur의 외회전 Kim HT, Wenger DR: J Pediatr Orthop, 1997.

• upward direction of sourcil

• “sagging rope” sign

Femoro-Acetabular Impingement (FAI)

1. Nonspherical femoral head

2. Narrowed head-neck junction

3. Overcorrected pelvic osteotomy

(localized or generalized acetabular overcoverage)

(retroversion or coxa profunda)

4. Combined extra-articular and intra-articular

impingement

FAI causes damage to the labrum and acetabular cartilage

• FAI: cause of early OA

• Two mechanisms of impingement

1) CAM impingement – nonspherical head

2) PINCER impingement – excessive acetabular cover

CLASSIFICATION OF END RESULTS

• Mose classification

• Stulberg classification

Radiographic result

• Very limited and not cover the myriad possible outcomes

• Fitting contour of the healed

femoral head on the AP & lateral

radiographs (concentric circles)

• Good outcome – 1 mm ↓

Fair outcome – 2 mm ↓

Poor outcome – 2 mm ↑

Mose template

• On the AP film - draw

best fit circle with

center on the

perpendicular line

Circle method

Radiographic result

• On the lateral film - does the same circle fit ?

Stulberg III if not fit within 2mm of circle

>2mm

No

Radiographic result

Stulberg classification

Group I A femoral head that cannot be distinguished from normal

Group II A round femoral head that fits within 2mm of the same circle on

both the AP and the frog-leg lateral radiographs

Group III An ovoid femoral head that does not fit within 2mm of the

circle on one or both views

Group IV A femoral head with at least 1 cm of flattening of the weight-

bearing area on one or both views

Group V A femoral head with collapse, usually central, within a round

acetabulum

• Based on residual femoral head shape

Radiographic result

Stulberg I

Can’t tell which hip

Rt. head larger, round

Stulberg II

Stulberg III

Ovoid head

Flattening

Stulberg IV

Gross incongruity

Stulberg V

Stulberg classification

• Group I and II - good long-term prognosis

• Group III and IV - mild to moderate degenerative

changes in late adulthood

• Group V - painful arthritis in early adulthood

Radiographic result

(Effective in predicting subsequent arthritic changes)

RESULTS OF LONG-TERM FOLLOW-UP (48 YEARS)

1. Most patients developed degenerative joint disease in their

fifties or later

2. 40% (THR), 10% (disabling osteoarthritis)

3. Prevalence of osteoarthritis: 10 times that found in the

general population in the same age range

(48-year follow-up study by McAndrew and Weinstein)

Thank you for your attention!