ROLE OF THE HIP ARTHRODIASTASIS IN MANAGEMENT OF THE PERTHES’ DISEASE

Abstract

Legg-Calve-Perthes’ disease (LCPD) is a form of osteonecrosis of the hip that is found in children . it is of unknown origin and self-limiting . It is known that bone death occurs in the head of femur due to an interruption in blood flow{1}. Classification of Legg-Calve-Perthes’ disease began with Catterall in 1971, who defined 4 types, the first two associated with a good prognosis and the 3rd and 4th associated with poor prognosis. The Salter-Thomson Classification simplifies the Catteral Classifications by reducing them down to two groups: group A (Catteral I, II) which shows that less than 50% of the head is involved, and group B (Catteral Ill, IV) where more than 50% of the head is involved. In Herring Classification, group (A) hips are those with no involvement of the lateral pillar of the femoral head, group (B) hips have some loss of height not exceeding 50% of the lateral pillar. group (C) hips have more than 50% loss of the lateral pillar . all classifications share the view that if less than 50% of the head is involved, the prognosis is good, while more than 50% involvement indicates a potentially poor prognosis{2}. Perthes’ disease in children above 8 years old, generally has a worst prognosis. On this age group it is common that hinge abduction appears in a descentered and uncontained hip. situation that has a difficult solution with the standard surgical procedures. On those cases arthrodiastasis as described, can be a valuable treatment option {3} . Arthrodiastasis is derived from the greek arthro {joint} dia {through} and stasis {stretch out}{3}. Arthrodiastasis is a relatively new treatment for Perthes’ disease. The term describes a regime of articulated distraction and open surgery of the hip, which has been used in Verona since 1979, in order to treat a variety of conditions such as osteoarthritis, chondrolysis and avascular necrosis . The rationale of arthrodiastasis using an external fixator in Perthes is that it permits to reduce the hip, protect it during the fragmentation stage, creating a vacuum phenomenon inside the acetabulum , “insufflate” the collapsed plastic head, permitting the reconstruction of a spherical head, creating a space between the bony surfaces, minimizing mechanical stress , applying tension along soft tissues during distraction stimulates microangiogenesis. and maintaining movement, the synovial circulation will be restored. This encourages fibrous repair of defects of articular cartilage and the preservation of an intact and congruent femoral head {4}. The Ilizarov fixator and other circular external fixators are preferred because unilateral fixators can`t maintain the correction achieved by the muscle release in patients with limited joint movement {5}.