Epidemiology, natural evolution, pathogenesis, clinical spectrum, and management of Legg-Calvé-Perthes

Abstract

Background: Legg-Calvé-Perthes disease is a self-limiting disorder that develops in children following interruption of the blood supply to the capital femoral epiphysis. This review outlines the current knowledge on the epidemiology, natural evolution, clinical spectrum, and management of the disease.

Methods: The literature pertaining to these aspects of the disease were studied and summarized in this review.

Results: Epidemiological studies suggest that environmental factors contribute to the causation of the disease. Incidence rates monitored over time indicate that the incidence of Legg-Calvé-Perthes disease is declining. The natural evolution followed on sequential plain radiographs enables division of the disease into Stages Ia, Ib, IIa, IIb, IIIa, IIIb, and IV. Reversible deformation of the capital occurs in Stages Ia-IIa simply on standing while irreversible deformation may occur in Stages IIb and IIIa. Treatment of Legg-Calvé-Perthes disease in Stages Ia-IIa aims to prevent the femoral head from getting deformed by containment and avoidance of weight-bearing. In Stages IIb and IIIa, treatment aims to remedy the effects of early irreversible deformation of the femoral head. In Stage IIIb and IV, treatment is directed to correcting the altered shape of the femoral head. The impression that these treatment methods are helpful is based on poor quality evidence.

Conclusion: There is an urgent need to undertake Level I studies to establish the efficacy of currently treatment.

Level of evidence: level V.

Keywords: Legg–Calvé–Perthes disease; containment; declining incidence; social deprivation; weight-relief.

Figure 1.

Diagrammatic representation of the vascular supply to the capital femoral epiphysis in children between the ages of 4 and 7 years (a). Interruption of the medial circumflex artery (b) or the lateral epiphyseal vessels (c) can produce avascular necrosis of part or the entire epiphysis.

Figure 2.

Perfusion MRI scan of the hips of a child with LCPD of the right hip. Four sequential cuts through the LCPD hip are shown (a–d) and corresponding cuts through the normal hip are shown on the right. The avascular region appears black (*) and occupies over 95% of the epiphysis.

Figure 3.

Very soon after the vascular insult, there is an attempt to restore the epiphyseal blood supply by recanalization of the occluded vessels (a). These recanalized blood vessels, however, can get obliterated if the epiphysis collapses (b).

Figure 4.

Stages of evolution of LCPD. The original Waldenström classification had four stages; stage of avascular necrosis (I), stage of fragmentation (II), stage of reconstitution (III), and healed stage (IV). In the modified classification, Stages I, II, and III are subdivided into early (a) and late (b) parts of the respective stages. Fragmentation commences with a vertical fissure, perpendicular to the articular surface (vertical white arrow—Stage IIa). In Stage II, metaphyseal cysts (black arrows) may be seen. Appearance of “wooly” new bone at the periphery of the epiphysis signals the beginning of Stage IIIa (horizontal white arrow).

Figure 5.

Radiographs of the hips of a child with LCPD of the right hip that was not treated. In Stage III of the disease (a), the femoral epiphysis is severely flattened. The details of changes in the proximal femur are shown in the tracing (b); the femoral epiphysis, consisting of new bone that has formed (red) on either side of the necrotic part of the epiphysis (black), has “mushroomed” well beyond the margins of the metaphysis (green). In response to mushrooming of the epiphysis, there have been repeated attempts to increase the width of the metaphysis by remodeling of the neck (purple lines). The disease healed and at skeletal maturity, there is coxa magna, a short neck, and an aspherical femoral head (c).

Figure 6.

Appearance of the right hip at onset of the disease (a) and at healing (b). Uniform loss of epiphyseal height which persists till the disease heals.

Figure 7.

Arthrogram of the hip of a child with LCPD demonstrating localized collapse of the femoral epiphysis under the acetabular margin.

Figure 8.

Diagrammatic representation of the unloaded hip (a) and on bearing weight (b) demonstrating reversible deformation of the femoral epiphysis on weight-bearing in the stage of avascular necrosis of LCPD. Increased width of the epiphysis results in extrusion of its lateral part (purple lines). Reduction of epiphyseal height also occurs.

Figure 9.

The femoral epiphysis may get deformed between Stages Ia and IIIa of LCPD.

Figure 10.

Diagrammatic representation of factors contributing to femoral head deformation during different stages of the evolution of LCPD (a–c) and the effect of femoral head deformation on revascularization of the epiphysis (d).

Figure 11.

Diagrammatic representation of methods of treating femoral head extrusion in LCPD. The extruded femoral epiphysis (a) can be contained by abduction the hip in a broomstick cast or an abduction brace (b) or by a proximal femoral varus osteotomy (c). Containment can also be achieved by reorienting the acetabulum by a Salter innominate osteotomy (d) or a triple pelvic osteotomy (e). A shelf acetabuloplasty (f) and a Chiari osteotomy (g) provide a cover for the extruded part of the femoral epiphysis without attempting to reverse extrusion itself.

Figure 12.

Diagram depicting hinge abduction. By Stage IIb or IIIa the femoral head may be deformed (a) and on attempting to abduct the hip (red arrow) the deformed femoral head may impinge on the acetabular margin and hinge on it such that the joint opens medially (b), creating a crescentic joint space. If the hinge abduction is reducible (c) a shelf acetabuloplasty is a recommended option (d). If the hinge abduction is irreducible (e), the hip is adducted (green arrow) and the position of maximum congruence is identified (f) and a proximal femoral valgus osteotomy is performed (g).