Legg-Calve-Perthes Disease

Question 1

What is the pathophysiology?

Answer 1

Osteonecrosis occurs secondary to disruption of blood supply to femoral head followed by revascularization with subsequent resorption and later collapse. creeping substitution provides pathway for remodeling after collapse

Question 2

What are the demographics?

Answer 2

M:F ratio 5:1 4-8y most common age Higher incidence in higher latitude areas and among caucasians

Question 3

What is perthes disease?

Answer 3

an idiopathic avascular necrosis of the proximal femoral epiphysis in children

Question 4

What type of femoral/pelvis osteotomies can be used?

Answer 4

Femoral varus osteotomy Salter osteotomy

Question 5

What are the indications for non-operative management?

Answer 5

Children <8y (bone age <6y) Lateral pillar A involvement

Question 6

What is the Differential diagnosis?

Answer 6

Unilateral:

1. DDH
2. Infection
3. Idiopathic AVN
4. Meyer’s dysplasia

Bilateral:

1. Skeletal dysplasias - MED, Spondyloepiphyseal dysplasia
2. Metabolic - Hypothyroidism, Hypophosphatemic ricketts, mucopolysacharidoses
3. Storage diseases - Gauchers
4. Others - steroid use, chemotherapy, radiotherapy

Question 7

What must be checked for if bilateral involvement?

Answer 7

Multiple epiphyseal dysplasia

Question 8

What is the Gage sign?

Answer 8

V-shaped radiolucency in lateral portion of the epiphysis and/or adjacent metaphysis

Question 9

What is the Catterall classification?

Answer 9

Group 1 - Anterior epiphysis only Group 2 - Anterior epiphysis with central sequestrum Group 3 - Only small part of epiphysis not involved Group 4 - Total head involvement

Question 10

What is a Salter osteotomy?

Answer 10

Single transverse cut above the acetabulum through the ilium to the sciatic notch Acetabulum hinges through the pubic symphysis Improves anterolateral coverage (can provide 20-25 degrees lateral and 10-15 degrees anterior)

Question 11

What is Meyer’s Dysplasia?

Answer 11

Question 12

What are the clinical features?

Answer 12

1 - Hip pain that can be referred to thigh or knee

2 - Limp

3 - LLD

4 - Restricted hip abduction and internal rotation

Question 13

What are early signs on radiographs?

Answer 13

Medial joint space widening - from less ossification of head Irregularity of femoral head ossification Crescent sign (subchondral fracture)

Question 14

What are variables of good prognosis?

Answer 14

Younger age <6y at presentation Sphericity of femoral head and congruency at skeletal maturity (Stulberg classification) Lateral pillar classification

Question 15

What are the indications for operative management?

Answer 15

Children >8y Lateral pillar B & B/C

Question 16

What percentage of cases are bilateral?

Answer 16

12%

Question 17

What is the Stulberg Classification?

Answer 17

Based on spherical congruency of the head: 1 - Normal 2 - Spherical congruency with loss of head shape <2mm 3 - Aspherical congruency with loss of head shape >2mm 4 - Aspherical congruency with flat head and acetabulum 5 - Aspherical incongruency

Question 18

What are poor prognostic indicators?

Answer 18

Females Decreased hip abduction Obesity Catterall ‘head at risk’ signs Stiffness with progressive loss of ROM

Question 19

Risk factors?

Answer 19

Low birth weight Positive family history Second hand smoke Asian/Central European/Inuit descent Abnormal birth presentation

Question 20

When can the Herring classification be used?

Answer 20

At the beginning of the fragmentation stage (usually 6 months after symptom onset)

Question 21

What are the Waldenstrom stages?

Answer 21

Initial Fragmentation Reossification Healing

Question 22

What are the broad treatment options?

Answer 22

<8 - observation >8 femoral and/or pelvic osteotomy

Question 23

What is the incidence?

Answer 23

1/10,000

Question 24

What is the Herring (Lateral Pillar) classification

Answer 24

Group A - pillar full height Group B - maintains >50% height B/C Border - approx 50% height (narrowed 2-3mm) Group C - >50% height maintained