MSK: Perthes Disease

Question 1

What is Perthes disease?

Answer 1

An avascular necrosis of the capital femoral epiphysis of the femoral head due to interruption of the blood supply, followed by revascularisation and reossification over 18-36 months

Question 2

Does it mainly affect males or females?

Answer 2

Males 5:1

Question 3

What age group does it occur in?

Answer 3

4 and 10

Question 4

What percentage of cases are bilateral?

Answer 4

10-20%

Question 5

It has a higher incidence among…

Answer 5

Lower socioeconomic class
Urban areas
High latitude 
Low birth weight 
Second hand smoke 
Caucasian, Asian, Inuit descent

Question 6

Describe the 4 stages

Answer 6

Necrosis - blood supply to femoral head disrupted and bone cells die. The area becomes inflamed and may last months

Fragmentation - over a period of 1-2 years the body removes dead bone and replaces it with softer bone. The bone is weaker and more likely to collapse into flatter position during this stage.

Reossification - new and stronger bone develops and begins to take shape. Often the longest stage.

Healed - bone regrown complete. How close the shape is to round will depend on the extent of damage during fragmentation phase as well as child’s age at disease onset

Question 7

How long can the whole process take?

Answer 7

2-5 years

Question 8

What are good prognostic factors?

Answer 8

Younger age at presentation
Spherical femoral head - not yet collapsed
Female

Question 9

How does it typically present?

Answer 9

Insidious onset
Limp
Pain at hip or knee

Question 10

What is found on examination?

Answer 10

Restricted ROM and stiffness on hip examination
Antalgic gait
Trendelenburg gait
Limb length discrepancy- late finding

Question 11

The condition may be initially mistaken for…

Answer 11

Transient synovitis

Question 12

If suspected, what investigations should be requested?

Answer 12

X ray of both hips
AP
Lateral
Frog leg

Question 13

Other than X-ray, what other scans can be helpful, especially if normal x ray and symptoms persist?

Answer 13

Technectium bone scan

MRI

Question 14

What can an x ray show?

Answer 14

Early signs: increased density in femoral head
Joint space widening
Irregularity of femoral head, flattening
Crescent sign

Question 15

What can MRI show?

Answer 15

Early features when other investigations are negative

Question 16

Will bloods be normal?

Answer 16

Yes

Question 17

How is it managed?

Answer 17

Usually non surgically
Rest, physio, crutches
In some cases: traction and plaster casts to keep femoral head in acetabulum
Surgery

Question 18

When is surgical management indicated?

Answer 18

Children over 6 (in those less than 6 prognosis is good with no intervention)
Severe disease

Question 19

What is there the potential for in adult life?

Answer 19

Degenerative arthritis

Question 20

What complications can occur?

Answer 20

Premature fusion of growth plates

OA

Question 21

Describe the catterall staging

Answer 21

Stage 1= clinical and histological features only
Stage 2= sclerosis with/without cystic changes and preservation of articulate surface
Stage 3= loss of structural integrity of femoral head
Stage 4= loss of acetabular integrity