Legg-Calvé-Perthes Disease- Clinical and Radiologic Manifestation -

부산대학교병원정형외과

김 휘 택

Introduction

• Legg-Calvé-Perthes disease is a syndrome.

(avascular event affects the capital femoral epiphysis)

• The etiology of the disease still is not understood.

• Efficacy of treatment remains a subject of controversy.

Etiology① Disruption of the blood supply to the proximal femur

② Coagulation abnormalities

③ Abnormal growth & development: “predisposed child”

④ Trauma

⑤ Hyperactivity or attention deficit disorder

⑥ Hereditary influences (genetic component)

⑦ Environmental influences

⑧ Synovitis

1. Disruption of the blood supply

Etiology

Μedial circumflex femoral artery

Lateral ascendingcervical artery

• Narrow passage betweenthe trochanter and capsule(<8 years old): prone to injury

• Double (and perhaps more)infarction

2. Coagulation abnormalities

• Thrombophilia→ abnormal thrombotic venous occlusion

• Deficiencies in protein C and S, hypofibrinolysis, and resistance to activated protein C

• Mutation in the factor V gene(factor V Leiden)

Etiology

3. Abnormal growth and development: the “predisposed child”

• Low birth weight, delayed skeletal maturation, shorter than normal → followed by a “catch-up” phase

• Abnormalities of thyroid hormone and insulin-like growth factors

Etiology

4. Environmental influences

• High occurrence in particular urban area and the lower socioeconomic groups

Etiology

“Unifying“ hypothesis

Hyperactivechild

Minor traumaTendency to form clots

Abnormality of the clot-lysing system

Clotting in the venous systemVenous pressure

rises in the femoral neck

Clotting propagates intothe femoral head

Infarction occurs

Etiology

Epidemiology

• Onset: common in 4-8 years (2-12 years) • Boys : girls = 4 or 5 : 1• Bilateral involvement: 10%-12% of patients• More common in whites, Asians, and Central

Europeans(unusual in blacks and native Americans)

Symptoms

①Painless limping - the most common (usually first noticed by a parent)

②Pain - 2nd most frequent symptoms (groin, anterior thigh, or knee)

Clinical manifestation

SignsAntalgic orTrendelenburg gait

LOM: primarily IR and abduction

Clinical manifestation

• Atrophy of the gluteus, quadriceps & hamstring m.• Apparent lower extremity length inequality ① Adduction contracture② True shortening on the involved side

because of CFE collapse

Signs

Clinical manifestation

① Older child② Obesity③ Female sex④ Marked restriction of motion

Clinical at-risk factors

Clinical manifestation

Natural history

• No definite natural history studies exist of persons who were completely untreated.

①Disease severity②Patient’s age at onset of disease③Duration of disease

1. Disease severity

• Considerably variable• Moderate symptoms for 12 to 18 months• The poorest results: the greatest degree of involvement• A number of classification systems: to estimate

severity of disease.

Natural history

2. Patient’s age at onset of disease

• The most consistent factor affecting course of disease

• < 6 years - mild disease6-9 years - moderate symptoms> 9 years or later - the most severe course and

worst outcome

Natural history

3. Duration of disease

• Outcome is also affected by duration of disease• The shorter the duration, the better the final results

Natural history

Imaging studies

① Diagnose ② Stage ③ Provide prognosis ④ Follow the course of the disease ⑤ Assess results

1. Radiography: (primary tool )

Modified Waldenström classification:(radiographic staging of disease evolution)

① Initial stage② Fragmentation stage③ Reossification (healing) stage④ Residual stage

Image studies – x-ray

• Subchondral fracture(Waldenström’s sign)

1. Initial stage

• Lateralization of the femoral head

• Widening of the medialjoint space (synovitis &hypertrophy of articularcartilage)

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

• 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:①until skeletal maturity②acetabulum also remodels

Other radiographic findings

Metaphyseal cyst or lucency • Poor prognostic value→ physeal cartilage

extending into themetaphysis

→ true cyst within theepiphysis or physis,metaphysis

Image studies – x-ray

“Sagging rope” sign• Radiodense line

overlying the proximal femoral metaphysis

• Anterolateral-inferior protruded portion of the femoral head

Image studies – x-ray

• Lateral extrusion of the capital nucleus- mushroom head

• Premature physealclosure with greater trochanteric overgrowth

Changes in the physis

Image studies – x-ray

MRI• Early Dx.• Configuration of the

femoral head and acetabulum

• Revascularization

• Hinge abduction• Its use as a prognostic

tool is not proven.

Image studies

Hinge abduction

Scintigraphy• Tc 99m bone scan• Transient photopenia:

false diagnosis • 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

Ultrasonography

• Not widely used

• Demonstrate effusion (synovitis) in early stages

• Assess the shape of the femoral head in later stage

Image studies

Computed tomography• Not typically used

• Demonstrate 3D images of the shape of the femoral head and acetabulum

Image studies

Pathogenesis of deformity

①Growth disturbance in the CFE and physis②Related to the disease process③Repair process itself④ Iatrogenic

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 trochantericovergrowth

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

Classification systems(Based on severity of disease)

①Catterall classification

②Salter-Thompson classification

③Lateral pillar classification

Group I Group II

Group III Group IV

No metaphysela reactionNo sequestrumNo subchondral fracture line

Sequestrum present – junction clearMetaphyseal reaction – antero/lateralSubchondral fracture line – anterior half

Sequestrum – large – junction scleroticMetaphyseal reaction – diffuse antero/lateralSubchondral fracture line – posterior half

Whole head involvementMetaphyseal reaction – central or diffusePosterior remodelling

Catterall classification

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

Classification

Central or diffuse

Diffuse anterolateral

AnterolateralNoMetaphysealreaction

Post. marginPost. 1/2Ant. 1/2NoSubchondralFx. Line

Whole headLargePresentNoSequestrum

EntireUp to 75%Up to 50%Ant. 25%CFE involvement

Group IVGroup IIIGroup IIGroup I

• 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 reliabilitycan be applied early in the course of disease

• Disadvantage - not all patients are diagnosed early duringthe phase of the subchondral fracture

Classification

Lateral pillar classification

Classification

• Based on the height of the lateral pillaron 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 maintainednarrow pillar little ossification

Pillar B/C border50% heightno collapse of central part

50% heightminimal density of lat. pillar

Lateral pillar classification

Classification

A loss of more than 50% of the original height of the lateral pillar (the worst 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 least50% of the original height

c) a lateral pillar with exactly 50% of the original height thatis depressed relative to the central pillar

Lateral pillar maintains at least 50% of its height (intermediate outcome)

No involvement of the lateral pillar (the best outcome)Group A

Group B

Group C

Group B/Cborder (new)

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 to a template of concentric circles.

• Good outcome – 1mm ↓Fair outcome – 2mm ↓Poor outcome – 2mm ↑

Mose classification

• Draw best fit circle with center on the center perpendicular line

Circle method

Radiographic result

• The lateral film-does the same circle fit?Stulberg III : greater than 2mm from circle fit

>2mm

No

Radiographic result

Stulberg classification

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

A femoral head with at least 1 cm of flattening of the weight-bearing area on one or both viewsGroup IV

An ovoid femoral head that dose not fit within 2mm of the circle on one or both viewsGroup III

A round femoral head that fits within 2mm of the same circle on both the AP and the forg-leg lateral radiographsGroup II

A femoral head that cannot be distinguished from normalGroup I

• Based on residual femoral head shape

Radiographic result

Stulberg I

Can’t tell which hip

R. 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 prognosisGroup III and IV - mild to moderate degenerative

changes in late adulthoodGroup V - painful arthritis in early adulthood

Radiographic result

Effective in predicting subsequent arthritic changes

Prognostic risk factors

1) Gage’s sign: a radiolucent V-shaped defect in thelateral epiphysis and metaphysis

2) Calcification lateral to the epiphysis3) Diffuse metaphyseal reaction4) Lateral subluxation of the femoral head5) Horizontal physis

1. Radiographic head-at-risk signs (Catterall)

1

1

1. Gage sign

2

2. calcification

2

3

2. calcification3. metaphyseal change

2

2

3

2. calcification3. metaphyseal change

4

5

4. subluxation5. horizontal

growth plate

- Catterall groups III and IV- Salter-Thompson group B- Lateral pillar group C- Lateral pillar group B (> 8 years old)

2. Hips at risk for a poor prognosis

Long-term prognosis① Age at onset: (young/old) ② Degree of involvement: (small/large)③ Duration of disease: (short/long)④ Congruency of the hip joint:

i) the most important predictorii) Careful containment of the head is important

Differential diagnosis

HemophiliaMultiple epiphyseal dysplasia

Eosinophilic granulomaLymphoma

Spondyloepiphyseal dysplasia

Infectious (inflammatory) DsGauchers disease

HypothyroidismUnilateral changesBilateral changes

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