Legg-Calvé-Perthes Disease (LCPD) is one of a group of disorders known as the Osteochondroses. The Osteochondroses typically are characterized by degeneration (avascular necrosis) and subsequent regeneration of the growing end of a bone (epiphyses). In Legg-Calvé-Perthes Disease, the growing end (epiphysis) of the upper portion (capital) of the thigh bone (femur) is affected. Researchers believe that an unexplained interruption of the blood supply (ischemia) to the capital femoral epiphysis results in degeneration (avascular necrosis) and deformity of the thigh bone in this area. Symptoms may include a limp with or without pain in the hip, knee, thigh, and/or groin; muscle spasms; delayed maturation of the femur (delayed bone age); mild short stature; and/or limited movements of the affected hip. The disease process seems to be self-limiting as new blood supplies are established (revascularization) and new healthy bone forms (reossifies) in the affected area. Most cases of Legg-Calvé-Perthes Disease occur randomly for no apparent reason (sporadically).
Legg-Calvé-Perthes Disease (LCPD) is characterized by degeneration (avascular necrosis) of the upper end of the growing portion of the thigh bone (capital femoral epiphysis) due to an unexplained interruption of the blood supply (ischemia) to this area, resulting in deformity of this part of the thigh bone. Age of onset, severity, duration, and associated complications of Legg-Calvé-Perthes Disease vary greatly from case to case.
Legg-Calvé-Perthes Disease usually affects children between the ages of eight and ten years, with some cases occurring as early as age two or as late as age 12 years. The disease typically affects one leg (unilateral); however, in approximately 10 percent of cases, the condition may subsequently develop in the other leg (bilateral).
In most children, the first symptom is a limp with or without pain. Affected children may experience pain in the hip, knee, thigh, and/or groin. In some cases, the pain may be limited (localized) to the knee or inner part of the thigh. In addition, affected children may also experience muscle spasms of the legs; loss of muscle mass (atrophy) of the front thigh muscles; limited movements of the hips; and/or inflammation of the membrane lining the hip joint (synovitis). As affected children age, they may also exhibit delayed overall maturation of the bones (delayed bone age) and mild short stature.
In all cases of Legg-Calvé-Perthes Disease, blood supply to the capital femoral epiphysis is re-established and degenerative (necrotic) bone regrows and rehardens (reossifies). This occurs without therapeutic intervention (spontaneously). In some cases, the regenerated bone may be misshapen (e.g., abnormally flattened or unusually enlarged). In almost all cases, some shortening of the leg occurs, and in more severe cases, the femoral head may be deformed. The length of time between onset of Legg-Calvé-Perthes Disease and new bone formation may be as short as 18 months or as long as four years.
When the onset of Legg-Calvé-Perthes Disease occurs during the ages of four to nine years, up to 38 percent, depending on treatment, of such affected children eventually develop osteoarthritis; when the onset occurs after the age of 10 years, the incidence rate nears 100 percent. Affected individuals who present significant deformity during reossification of the capital femoral epiphysis have an increased risk of developing osteoarthritis later in life.
In most affected individuals, Legg-Calvé-Perthes Disease appears to occur randomly for unknown reasons (sporadically). Very rarely, the disorder may be familial, suggesting autosomal dominant inheritance. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother.
In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed “dominating” the other normal gene and resulting in the appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child. The risk is the same for each pregnancy.
Some researchers suggest that Legg-Calvé-Perthes Disease may be caused by the interaction of many genes (polygenic inheritance), possibly in combination with environmental factors (multifactorial inheritance).
The symptoms of Legg-Calvé-Perthes Disease develop due to damage to the growing portion (epiphysis) of the upper end (capital) of the thigh bone (femur). This damage is thought to result from interruption of the blood supply (ischemia) to the capital femoral epiphysis. This causes damage to bone-forming cells (osteoblasts) and results in degeneration (necrosis) and softening of the bone in this area. The capitol femoral epiphysis becomes fragile as bone mass is lost. It is possible that this fragile area may “fracture” internally, causing deformity of the capital femoral epiphysis. A thin line of decreased density (Caffey sign) may be apparent on the epiphysis, which may represent such a “fracture” within the bone (subchondral). Damaged bone may fragment and cause irregularities when normal blood flow to the affected area eventually resumes (revascularization). As the bone regrows and rehardens (reossifies), it may deform, resulting in permanent malformation of the upper thigh bone (e.g., abnormally flattened or unusually enlarged epiphysis).
Legg-Calvé-Perthes Disease affects males approximately four to five times as often as females (4-5:1). According to reports in the medical literature, when the disorder occurs sporadically, males are predominantly affected. However, in families with more than one affected member (kindreds), the disorder appears to occur relatively equally among males and females. Reported cases of Legg-Calvé-Perthes Disease include several individuals within multiple, multigenerational families.
The disorder usually affects children between the ages of six and 10 years; however, associated symptoms and findings may become apparent as early as age two or as late as age 12.
In most children with Legg-Calvé-Perthes Disease, the first sign is a limp with or without pain in the hip, knee, thigh, or groin. Ordinary radiograms are almost always diagnostic. The diagnosis may be confirmed by a thorough clinical evaluation, a detailed patient history, and/or a variety of specialized tests, such as magnetic resonance imaging (MRI), arthrography, scintigraphy, and/or sonography. During MRI, a magnetic field and radio waves are used to create cross-sectional images of the upper end of the thigh bone (capital femoral epiphysis) and may demonstrate abnormal development of the epiphyses. Arthrography, in which an opaque substance is injected into a joint before X-rays are taken, is especially helpful in showing the cartilage surface of the bone. The X-rays may help to determine the shape of the end of the bone where it joins (articulates) with the hip. Bone density may be evaluated using a specialized technique known as scintigraphy. During scintigraphy, the individual ingests a radioactive substance that will accumulate in the target area (e.g., bones). A specialized camera is then used to detect the levels of radioactivity present in these structures, producing an image of the targeted structure. In sonography, reflected sound waves create an image of certain tissues and body structures and may detect characteristic changes in the hip and femur, such as Caffey sign.
The treatment of Legg-Calvé-Perthes Disease is directed toward the specific symptoms presented by each individual. Treatment varies with the severity of symptoms and may require the coordinated efforts of a team of specialists. Pediatricians usually refer patients to specialists who diagnose and treat disorders of the skeleton, joints, muscles, and related tissues (orthopedists); physical therapists; and other health care professionals may need to systematically and comprehensively plan an affected child's treatment.
Degenerative bone changes associated with Legg-Calvé-Perthes Disease usually heal on their own without intervention (spontaneously). Affected children should be closely monitored so the progression of the disease may be evaluated to ensure the bone reforms properly. Radiologic studies (e.g., MRI, arthrography, scintigraphy) may be used to assist in monitoring the progression of the disease.
In other cases, decreased physical activity, bedrest (if pain is present and prolonged), and/or stretching exercises (if stiffness occurs), particularly exercises in which the legs are rotated away from the body (abduction exercises), may be recommended to decrease pain in the hip and maintain proper mobility of the joint. In addition, as an affected child ages and regrowth of the epiphysis occurs, physicians must ensure that epiphyseal growth is contained within the cavity of the hip bone (acetabulum) where the thigh bone (femur) and hip normally meet (articulate).
Nonsurgical treatment may include a special brace or cast to keep the ball of the joint completely within the socket (acetabulum) so that it will not deform while healing. Surgical treatments may include various procedures designed to place and keep the ball within the socket.
Physicians may rely upon specific classification systems to make certain decisions concerning treatment and predict an affected individual's long-term progress. For example, the Stulberg Classification System, created in 1981, defines five outcome categories based upon the shape of the femoral head and its relationship with the hip socket (as seen upon x-ray imaging studies). The different classifications are used to predict the potential risk of developing degenerative changes of the hips (osteoarthritis). However, a recent study has demonstrated that there may be inconsistencies among the standards used by physicians when assigning these classification categories. Because the use of differing definitions may alter the validity of outcome evaluations, the study's authors suggest that physicians must be aware of possible variances among those assigning these classifications and that additional methods should be used to characterize the condition and relate it to long-term treatment outcome.
Early intervention is important to ensure that children with Legg-Calvé-Perthes Disease reach their potential. Some orthopedic surgeons describe the objective of treatment as a means of obtaining the “foundest of balls in the roundest of sockets” to reduce the chance of osteoarthritis and total hip replacement early in life. Genetic counseling may be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.
Research on genetic disorders and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic and familial disorders in the future.
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