- 1 in 10000, 4-8 years of age, males affected more
- Insidious onset, may cause painless limp, intermittent hip, knee, groin or thigh pain
- Loss of internal rotation and abduction is classical
- Pathophysiology : Osteonecrosis occurs secondary to disruption of blood supply to femoral head; Revascularization with subsequent resorption and later collapse
- X Ray- AP of pelvis and frog leg lateral
- Bone scan and MRI to diagnose early in suspected cases
- Catterall and Herring pillar are two commonly used classification systems
- Non operative management in < 8 years of age, lateral pillar A involvement
- Operative management in > 8 years of age, especially lateral pillar B and B/C
- Osteotomies are most effective when performed before the advanced fragmentation phase
- Femoral head deformity, Lateral hip subluxation (extrusion), Premature physeal arrest, Acetabular dysplasia, Labral injury, Degenerative arthritis are common complications
