Legg-Calve-Perthes disease is an orthopedic disorder characterized by aseptic necrosis of the femoral head. It generally manifests during childhood.
The typical presentation is that of a limping child not claiming any pain. Most LCP patients present with unilateral symptoms, but about 20% of affected children suffer from bilateral LCP.
Usually, affected children continue to carry out their day-to-day activities as normal. If pain is reported, it is not necessarily limited to hip and pelvic area but may radiate to groin, buttocks, thighs and knees. Those body regions are innervated by nerves that also supply the hip joint and sensations are consequently assigned to the aforementioned areas. The fact that pain is rarely located at the site of lesion tends to delay diagnosis of LCP. In most cases, no traumas are reported to have triggered claudication or pain.
Periarticular swelling has been observed.
Children suffering from LCP may have a slightly shorter stature than their peers.
Since LCP patients may initially be diagnosed with an undefined skeletal disorder and/or growth retardation, the family's history regarding incidence of orthopedic, vascular and endocrinological disorders should be obtained. In order to rule out the latter, complete hemogram and blood biochemistry should be prepared and evaluated. In LCP patients, analyses of blood samples generally don't reveal anomalies.
Diagnosis of LCP requires diagnostic imaging. Usually, plain radiographs are sufficient to confirm necrosis of the femoral head and to assess its severity. Anteroposterior and frog-leg lateral views are recommended, although the latter may be sufficient to diagnose LCP .
During the ischemic stage of the disease, plain radiographic images reveal an increased joint space. This finding is also designated Waldenström's sign which is considered to be a non-specific indicator of hip disorders associated with joint effusion. Osseous anomalies may only appear after a few months. Decreased bone density and irregular contour of the femoral head are most often detected, but changes in acetabular tissue structure have been described, too . If compression fractures occur, these may be recognized as an isolated line of increase bone density traversing the femoral head.
In stage II, X-rays may show calcified fibrous tissue replacing necrotic tissue. Also, metaphyseal cysts are a frequent finding during this stage of LCP, but large, osteolytic areas are only detected in more severe cases. Such a result is generally referred to as Gage's sign. The joint space continues to widen.
In general, bone density increases during reossification, beginning at the epiphyseal margin of the lesion and spreading towards the opposite border. In severe cases, irregularities of both articular surfaces or a flat, shrunken or even enlarged femoral head may become visible towards the end of this stage of LCP.
Sometimes, incongruencies manifest only during the remodeling stage.
If doubts remain as to the origin of femoral head anomalies, bone scintigraphy may be carried out.
Young children, i.e., those aged less than five or six years, who don't present limitations of hip motion range may be treated conservatively. In this context, non-steroidal inflammatory drugs are generally prescribed to relieve acute pain. Additionally, children who present with moderate symptoms should were abduction pants or braces. While prolonged bed rest is not required, patients should rest during periods of pain. These children benefit from physiotherapy and/or swimming. They should be instructed not to jump.
If epiphyseal involvement exceeds 50%, subluxation or femoral head extrusion occurs, and patients are older than five years, femoral or pelvic osteotomy may be required. It has been suggested that pelvic osteotomies are associated with better outcomes in younger children.
Surgery may be less beneficial in school children. Reossification and remodeling capacities are already decreased at this age and generally, non-surgical containment is initially preferred over surgical intervention . However, the latter may be indicated during later stages of the disease.
Initial confinement is of little use in children aged more than twelve years. Salvage procedures should be realized upon diagnosis to restore congruency of femoral head and acetabulum.
Hip arthroplasty is rarely indicated but may become necessary decades later if osteoarthritis develops.
Disease progress and recovery should be monitored in regular follow-ups and radiographic examination in all cases.
Most LCP patients have a good prognosis and reach normal height during their adolescence. As has been indicated above, the individual prognosis largely depends on condition and congruency of articular surfaces of the femoral head and acetabulum. Congruency is less likely to be obtained in severe cases, i.e., if avascular necrosis affects large parts of the femoral head instead of isolated portions. Reossification and remodeling capacities decrease with age. Thus, young children tend to have a better outcome than older ones. However, young age may not compensate for extensive necrosis .
In general, LCP patients are at higher risks of developing coxarthrosis than the remainder of the population and less than 50% of those children affected by LCP will not suffer from this degenerative condition . The individual risk is low if spherical congruency is achieved. Aspherical congruency is still related to a good long-term prognosis, although osteoarthritis may develop decades later. Incongruency is an unfavorable prognostic factor and is usually associated with severe coxarthrosis at young age.
Although the majority of LCP patients is male, females tend to suffer more severe LCP and have a worse long-term prognosis.
The vast majority of LCP cases occurs sporadically, but familial accumulation has been described in isolated cases. To this end, most recent findings imply type II collagenopathies to play a major role in LCP pathogenesis  . According to current knowledge, they are inherited with an autosomal dominant trait.
Type II collagen is mainly found in hyalin cartilage and the latter is the basic element of the primordial skeleton, e.g., of the cartilaginous precursor of osseous tissue at sites of endochondral ossification. Although these assumptions may serve as an explanation for growth plate damage and subsequent epiphyseal lesions, it has neither been clarified how cartilage anomalies result in ischemia nor why systemic collagenopathies only manifest at the femoral head.
Presumably, other, as of yet unidentified genetic disorders contribute to juvenile avascular necrosis of the femoral head and indeed, the idea of polygenic inheritance has been proposed a long time ago .
It has been speculated that environmental factors may either cause LCP in predisposed individuals or modulate severity. Repetitive trauma has been proposed as a possible trigger . However, additional research is required to confirm this hypothesis.
The overall incidence of LCP has been estimated to be 4 per 100,000 children.
Boys are affected approximately four times as often as girls. LCP is most frequently diagnosed in preschoolers and school-aged children. The mean age of symptom onset is 7 years.
LCP disease progress typically follows a pattern of four stages, whereby pathologic alterations are induced during the first, ischemic stage. Epiphyseal growth plates consist of hyalin cartilage and as such, are scarcely supplied with blood. Histologic analyses show vessels in metaphyseal osseous tissue, in the ossification zone and in epiphyseal parts of the bone. Osteoblasts, those cells that are responsible for bone formation, are located within the ossification zone and depend on those capillaries supplying this part of the growth plate. Significant shortages in blood supply thus result in osteoblast cell death, halted growth and necrosis of the femoral head. The capital femoral epiphysis loses bone density and becomes more susceptible to trauma. Fractures may occur. This stage of LCP lasts up to one year.
Stage II is characterized by revascularization and resorption. Restoration of blood supply allows for fibrous tissue to develop, degrade and replace necrotic cells. This may initially be associated with a further reduction of bone resilience. If the femoral head is now subjected to physiological loads, deformation may become an issue. Similar to stage I, this phase of the disease also lasts about one year.
In stage III, reossification takes place: Now, osseous tissue replaces connective tissue that filled volume defects during stage II. Metaphyseal reossification is usually directed from the epiphyseal border of the lesion towards the diaphyseal one. If all layers of the growth plate reossify, growth will come to a halt because this newly formed osseous bridge tightly attaches epiphysis and diaphysis. This stage lasts up to two years. In most cases, femoral head deformities are not recognizable after complete re-ossification.
Finally, stage IV comprises remodeling processes that aim at adjusting osseous microstructure and trabecular orientation to mechanical loads. Articular surfaces may either remain spherical and congruent, aspherical and congruent or aspherical and incongruent. The condition of both femoral head and acetabulum and their congruency to each other is related to the patient's long-term prognosis. Similarly, therapeutic measures are generally evaluated regarding to the possibility to reach congruency.
No specific measures can be recommended to prevent disease onset. In order to avoid long-term sequelae, treatment should aim at regaining hip motion range and establishing congruency of articular surfaces.
Legg-Calve-Perthes disease (LCP) is an orthopedic disease pertaining to a group of disorders designated osteochondroses . In general, the term osteochondrosis refers to disturbances in endochondral ossification, i.e., formation of osseous tissue from cartilaginous precursors. Endochondral ossification is of particular importance for longitudinal growth of long bones like those of upper and lower limbs and takes place in epiphyseal growth plates. Therefore, an impairment of this process usually affects the epiphyses of these bones and symptoms manifest during childhood or adolescence. Clinically, an osteochondrosis is characterized by epiphyseal necrosis and subsequent remodeling and repair processes. In LCP, these pathophysiological events affect the femoral head.
LCP may sometimes also be referred to as Perthes disease or juvenile avascular necrosis of the femoral head. The latter designation hints at what is assumed to cause this disease: a shortage in blood supply. Little is known about the causes of ischemia. It provokes avascular and aseptic necrosis of the femoral head and children affected by LCP typically claim pain in hip, groin, pelvis and legs. Hip motion range is often limited. Overall growth may be restricted slightly and LCP patients tend to present with shorter statures. However, the disease is self-limiting and resolves with revascularization and reossification.
Legg-Calve-Perthes disease (LCP) is an orthopedic disorder characterized by degeneration of the femoral head due to reduced blood supply. LCP is mainly diagnosed in preschoolers and school-aged children. It is a self-limiting disease that is generally not associated with severe sequelae.
Most cases occur sporadically, i.e., without events in personal or familial history providing an explanation for symptom onset. To date, the most widely accepted hypothesis regarding LCP etiology is that of several genes predisposing patients and environmental factors triggering femoral head ischemia. A variety of genes that may contribute to LCP has been identified: These genes encode for collagen type II, a connective tissue fiber mainly encountered in hyalin cartilage. The latter is present in growth plates and joints.
Restricted blood supply to the femoral head results in local cell death - necrosis - and growth retardation. Necrotic tissue is less resistant than healthy bones and the femoral head may deform under usual mechanical loads. This process may be associated with pain, but many LCP patients merely limp and don't report any pain. If pain is experienced, it may radiate from hip and pelvis to groin, buttocks, thighs and knees. Growth retardation is generally mild, but LCP patients may be shorter than their peers.
LCP is diagnosed by means of plain radiography. Anomalies regarding joint space, articular surface contours, bone density and position of femoral head and pelvis relative to each other can be assessed with the help of radiographic images.
Additional diagnostic measures, e.g., laboratory analysis of blood samples, mainly serves to rule out differential diagnoses.
Therapy depends on the age of the child, the extent of femoral head necrosis as well as radiographic findings like subluxation or femoral head extrusion. Young children tend to have better outcomes than older children and may only require conservative treatment in form of analgesics, rest during periods of exacerbation and physiotherapy. Children suffering from severe LCP as well as those who are older than five or six years may require surgery.
Any treatment aims at relieving pain, recovering hip motion range and establishing congruency between femoral head and pelvis. This is of utmost importance to reduce the long-term risk for hip arthrosis.