Perthe's disease

Perthe’s disease is defined as a self-limiting disease in children largely limited by age and sex which results from the changes in the capital femoral epiphysis secondary to the arrest of the blood supply.

The disease was first described by Waldenstrom in 1902 mistakenly ascribed it to be TB. In 1910, Legg, Calve, and Perthe’s independently described about it and in 1922 Waldenstrom correctly described the stages of the disease.

Perthe’s disease is seen from the age of 18 months to 12 years and the peak incidence seen during 4 years to 12 years. Males are most commonly affected, the male to female ratio is 4:1. Most of the cases have unilateral involvement, bilateral involvement seen in 10% to 12% of cases.

Etiology :

• Inoue’s multiple hit theory – Multiple episodes of infarction are required to produce Perthe’s disease.
• Venous drainage – Perthe’s disease is associated with increased venous pressure in the affected neck. Abnormal venous drainage pattern is seen in the initial and fragmentation stage.
•  Abnormal growth and development (The Predisposed Child) – The bone age is delayed than the chronological age by 2 or more years. Maturation is more delayed in bilateral than unilateral cases. Children, at diagnosis have a short stature as compared to their peers.
• Trauma – The blood vessels supplying the epiphysis has to pass through narrow passage due to which they are susceptible to damage due to trauma.

Stages of Perthe’s disease

1.    Initial Stage : Also called as Increased density stage. Limp and pain is variable, often mild and intermittent.

2.    Fragmentation Stage : Pain and limp worsens and patient may lose range of motion. Abduction and internal rotation are most affected. head shows fragmentation may lateralise and flatten.

3.    Re-ossification Stage: Limp and pain gradually resolves and range of motion improves. Femoral head gradually re-ossifies and flattening may improve.

4.    Residual Stage : Occasional limp, locking  or popping may be present. Osteochondroitic lesion may develop.

Natural History of Perthe’s disease 

            Disease severity varies from mild to severe with most of patients experiencing moderate symptoms for 12 to 18 months followed by complete resolution of symptoms and return to normal physical activities. Patients age is the most important factor affecting course of disease. Patients with early onset (<6 years) have mild disease than those with onset between 6 and 9 years have moderate symptoms while those with onset after 9 years have severe symptoms and worst outcome.