Legg calve perthes disease is a disorder in hip joint due to ischemia of the femoral epiphysis, resulting in avascular necrosis, followed by revascularization and re ossification over 18 – 36 months.(1)
The etiology is unknown. But infection, trauma and transient synovitis have been proposed but unsubstantiated. In stead of that factors leading to thrombophilia and a reduced tendency to lyses thrombi have been identified.
Legg calve perthes disease is more common in boys who are in 5 – 10 years of age. It mainly affect boys than girls. Male female ratio is about 5:1 and It is bilateral in 10% – 20% children.(1)
The most common presenting symptom is a limp of varying duration. Pain, if present, is usually activity related. The pain may be localized in the groin or referred to the anteromedial thigh or knee region. Thigh or knee pain in the child may be secondary to hip pathology. Onset of the disease is more acute. The condition may initially be mistaken for transient synovitis (1). Parents often report that symptoms were initiated by a traumatic events.
Subsequent degenerative arthritis in adult life, Deformity in gate
This is useful in diagnosis, management and assece prognosis. Need anterior-posterior and lateral X-ray and series of X-ray with time. Initial X-ray may be normal. Increase density in femoral head and subsequently become fragmented irregular. (1)
There are several classifications like Catterall, Salter-Thompson and Herring. But most widely used classification is Herring classification. This is a radiographic classification system which helps to determine treatment and prognosis during the active stage of the disease.
Herring classification :–
Head is divided in to 3 sections or pillars which are lateral (12% - 30%), central (50%) and medial (20% - 35%). The degree of involvement of the lateral pillar can be subdivided into three groups.
Group A - the lateral pillar is radio graphically normal.
Group B - the lateral pillar has some lucency but >50% of the lateral pillar height is maintained.
Group C – the lateral pillar is more lucent that in group B and <50% of the pillar height remains.
In most cases prognosis is good. If age is less than 6 years and involment of epiphysis less than half, prognosis is good. But if gage is more than 10 years and involment of epiphysis more than half, prognosis is bad. (1) Hips classified as Catterall groups iii and IV, Salter-Thompson group B, and lateral pillar group C are at risk of a poor prognosis.
No special treatment. The goal of treatment is to create spherical, well-covered femoral head with hip range of motion that is close to normal. Bead rest, traction may required. But in severe case, the femoral head needs to be covered by the acetabulum to act as a mould for the reossifying epiphysis. This is done by maintaining the hip in abduction with plaster or calipers of by performing femoral or pelvic osteotomy (1). Late surgery for deformity or late surgery for osteoarthritis may required.
1. Tom Lissauer, Graham Clayden. Illustrated textbook of paediatrics, 3rd edition: Bones, joints and rheumatic disorders. Tauny Southwood, Professor of pediatric rheumatology, p435