Legg-Calve-Perthes disease (LCPD) is a self-limited childhood hip disorder of unknown etiology that can produce permanent deformity of the femoral head. Legg, of the United States; Calve, of France; and Perthes, of Germany, independently described the disease in 1910.¹ The onset of LCPD is between 2 and 15 years of age, with a peak between 4 and 9 years. Sundt, in 1920, reported that boys were four times more likely to have the disease than girls and that 10% of patients developed bilateral disease.² Molloy and MacMahon, in 1966,³ and Catterall, in 1981,⁴ reported similar findings, with bilateral disease occurring in 10% to 15% of patients and a male-to-female ratio of 4-5:1. The diagnosis of LCPD requires either plain radiography or magnetic resonance imaging along with a careful history and physical examination. Symptoms and physical findings with early LCPD are nonspecific, and the diagnosis can often be one of exclusion. Other pediatric conditions that produce femoral head osteonecrosis or LCPD-like changes on radiography must be ruled out by performing a thorough history, physical examination, and radiographic assessment.

LCPD is a challenging condition to treat, with a wide age range of presentation and both variability in stage and severity of disease. Despite more than a century of research and treatment directed at LCPD, there is currently no consensus on the optimal treatment for it. However, there is agreement that the primary goal of treatment is to prevent further femoral head deformity and maintain hip sphericity. Femoral head deformity, although tolerated best in younger children, will lead to arthritis, pain, and dysfunction over time.⁵,⁶

Plain radiography remains the primary diagnostic assessment tool for LCPD. An anteroposterior (AP) and frog-lateral radiograph of the pelvis are used to determine the radiographic stage of the disease, the extent of head involvement, and serial progression of the disease. Catterall⁴,⁷ described a series of classic head-at-risk signs during the progression of the disease including lateral subluxation, Gage sign (V-shaped radiolucency in the lateral portion of the epiphysis and/or adjacent metaphysis), calcification lateral to the epiphysis, and horizontal alignment of the growth plate. These are late radiographic signs of a “head at risk” for having a poor prognosis. More recently, research effort has been focused on using earlier radiographic features to determine the prognosis and long-term outcome.

Waldenstrom⁸ described four radiographic stages of disease progression: the initial or avascular necrosis stage (stage I), fragmentation or resorptive stage (stage II), reossification or healing stage (stage III), and healed stage (stage IV). Herring et al⁹ found that the time from first radiographic evidence of disease to start of fragmentation had a mean of 6 months (range, 1 to 14 months), with the fragmentation stage lasting 8 months (range, 2 to 35 months) and the reossification stage lasting 51 months (range, 2 to 122 months).

In 2003, Joseph et al¹⁰ reported their modification of the Waldenstrom staging described in 1972 by Canale et al¹¹ The modified staging is referred to as the Elizabethtown classification. Each of the first original three stages described by Waldenstrom was further subdivided into two substages as stages Ia, Ib, IIa, IIb, IIIa, IIIb, and IV (Figure 8.1). Stage Ia is the initial stage of the disease, characterized by sclerosis of the epiphysis without any loss of epiphyseal height. In stage Ib, the epiphysis is sclerotic, and there is loss of epiphyseal height. There has not yet been fragmentation of the epiphysis, and the epiphysis remains as a single piece. In stage IIa, the epiphysis begins to fragment with bone resorption, which is seen on radiograph as radiolucent perpendicular lines relative to the epiphysis on either the AP or frog-lateral view of the hip. Stage IIb represents further fragmentation and collapse, with maximal flattening
and multiple perpendicular lucencies representing severe fragmentation. Stage IIIa represents the beginning of the healing stage, with new bone formation seen at the lateral epiphysis. This reossification occurs at the periphery of the necrotic fragment, and the new bone is not of the same radiodensity and covers less than one-third of the circumference of the epiphysis. In stage IIIb, the new bone of normal radiodensity now covers more than one-third of the circumference of the epiphysis. Finally, stage IV represents completion of healing, and there is no radiographically identifiable avascular bone. These modifications to the original classification demonstrated good inter- and intraobserver reliability. Joseph et al¹⁰ calculated the duration of the initial four stages (Ia to IIb) to be approximately 4 months for each stage and the duration of stages IIIa and IIIb twice and thrice that of the preceding stages, respectively. It appears that the greatest amount of epiphyseal extrusion and flattening occurs in late fragmentation, leading to the recommendation of attempting to “contain the hip” or prevent further deformity by placing the hip in the socket for protection prior to stage IIb.

The concept of containment was first described by Harrison and Menon in 1966 as follows¹²: “[I]f the head is contained within the acetabular cup, then like the jelly poured into a mold, the head should be the same shape as the cup when it is allowed to come out after reconstruction.” Containment is the term used to describe interventions that place the anterolateral part of the femoral epiphysis within the acetabulum, thereby protecting the epiphysis from being subjected to deforming stresses. This concept was further advanced by the work of Robert Salter, who, using a piglet model, created a Perthes-like condition by ligating the arterial supply of the femoral head.¹³,¹⁴ In his studies, he demonstrated that the outcomes were optimal in the pigs treated with abduction, regardless of weight-bearing status. Both
operative and nonoperative treatments have been popularized to take advantage of the “plasticity” associated with the early stages of LCPD and relative femoral head fragility. The main overriding principle is that for containment to work, the goal is to intervene in the early stages (stage Ia-IIb) and contain the femoral head before extrusion of the lateral epiphysis, which can typically be seen in late fragmentation and early ossification.¹⁵

In children older than 8 years at onset of disease, extrusion of the lateral aspect of the femoral head can occur quickly in the course of the disease, and hence containment should be initiated as soon as the diagnosis is made.¹⁰,¹⁶ In children younger than 8 years, the like-lihood of extrusion developing is less certain, and close monitoring with conservative therapies can be a reasonable first line of therapy, provided that close monitoring with clinical and radiographic examination occurs every 3 months. Containment can be achieved by two different methods. The first involves positioning the femur in abduction/internal rotation or abduction/flexion, which can be achieved by casting, bracing, or surgery on the femur. Alternatively, containment can be achieved by an osteotomy of the pelvis that reorients the acetabulum such that it covers the anterolateral part of the femoral epiphysis (eg, Salter or triple pelvic osteotomy) or by creating a bony shelf over the extruded part of the epiphysis. For children under 8 years at onset, the outcomes of brace treatment and surgical containment are approximately equal.¹⁷,¹⁸

It is imperative that an adequate range of motion of the hip is present when containment treatment is instituted, as a stiff hip cannot be contained. In the early stages of LCPD, the hip is irritable and associated with synovitis, which can lead to inflammation and guarding of the hip with movement. This is typically manifested with a limp that can be insidious in onset and frequently present toward the end of a particularly active day in younger children. Older children tend to present more acutely with pain, dysfunction and ambulatory difficulty. First-line therapy for the early stages of nonoperative containment include rest, physical therapy, nonsteroidal anti-inflammatory drugs (NSAIDs), and restriction of weight-bearing. Depending on the age at presentation, restriction of weight-bearing may be achieved by using a wheelchair, walker, or crutches. In addition to the use of a short course of NSAIDs, an intra-articular steroid injection may be beneficial to help reduce inflammation and decrease pain in the early symptomatic phases of the disease. In most situations, restricting weight-bearing will decrease the hip pain. Children are able to participate in school in their wheelchair or with their crutches so as to avoid missing prolonged periods of school.

The early stages of LCPD can last between 1 and 2 years, depending on when the initial diagnosis is made. In addition to avoiding high-impact activities and restricting weight-bearing, consideration of a bracing program is also critical to facilitate nonoperative containment. The most effective position to decrease intra-articular pressure is a combination of slight flexion, abduction, and external rotation.¹⁹,²⁰,²¹ Positions associated with full extension can increase hip capsular pressure and lead to more symptoms associated with LCPD. Various abduction orthoses and casting have been shown to effectively “contain” a symptomatic hip nonsurgically. Petrie and Bitenc described a weight-bearing cast in abduction that allowed the child to be more active and functional within the family home.²² The typical position described is close to 45° of abduction and 5° to 10° of internal rotation with about 10° to 15° of knee flexion held in two long leg casts with a bar holding the legs in the set position, which has come to be known as Petrie casts.

A number of more convenient weight-bearing orthoses have been subsequently described to emulate the position and function of the Petrie casts.²³,²⁴,²⁵ The initial results with abduction braces were positive; however, long-term follow-up has demonstrated inconsistent results.²⁶,²⁷ The most recent report on 25-year experience with abduction A-frame orthosis has been positive.²⁴ To be successful, the authors describe a regime of wearing the brace for 20 hours per day for 13 months on average during the early stages of the disease (Figure 8.2A-D). In their cohort, the majority of hips at maturity were spherical without evidence of arthrosis or significant femoral head deformity. Abduction bracing can be seen as tedious and labor intensive and may not be attractive to parents looking for a “quick fix” for their child’s disease. Occasionally, activity modification, physical therapy, and bracing are not enough to settle down an irritable hip, and additional measures are required to surgically “contain” the hip in the socket. These operative measures are described below.