Approach to Legg Perthes

Note the age group: usually 4-10 year olds, predominantly males
Unproven (but possible) association with clotting abnormalities; thyroid disorders
Goes through stages: blood supply is injured, ossific nucleus stops growing, cartilage widens, then subchondral fracture, then fragmentation, then resorption and new bone formation (healing)
The goal is to keep the hip as normal and supple as possible during the course of the disorder

Consider on the differential: Meyer’s dysplasia, MED, SED, hypothyroidism, Gaucher’s, corticosteroid AVN

The key on the physical is to note their hip range of motion – can they abduct? The development of an adduction contracture is bad. Check to see what else is limited.

The number one prognostic factor is their age of onset – less than 8 tend to do well; after 8 tend to do more poorly

Herring lateral pillar classification: based on an AP pelvis x-ray – most prognostic classification
– A – lateral pillar okay; B – lateral pillar >50% intact; C – lateral pillar