Legg–Calvé–Perthes disease

Legg–Calvé–Perthes syndrome
X ray of Legg–Calvé–Perthes disease of the left hip
Classification and external resources
Pronunciation	/ˈlɛɡ.kælˈveɪ.ˈpɜːrtiz/, /ˈlɛɡ.kɑːlˈveɪ.ˈpɜːrtᵻz/
Specialty	Orthopedics
ICD-10	M91.1
ICD-9-CM	732.1
OMIM	150600
DiseasesDB	9891
MedlinePlus	001264
eMedicine	radio/387
MeSH	D007873

Legg–Calvé–Perthes disease (LCPD) is a childhood hip disorder initiated by a disruption of blood flow to the ball of the femur called the femoral head. Due to the lack of blood flow, the bone dies (osteonecrosis or avascular necrosis) and stops growing. Over time, healing occurs by new blood vessels infiltrating the dead bone and removing the necrotic bone which leads to a loss of bone mass and a weakening of the femoral head.^[1] The bone loss leads to some degree of collapse and deformity of the femoral head and sometimes secondary changes to the shape of the hip socket. It is also referred to as idiopathic avascular osteonecrosis of the capital femoral epiphysis of the femoral head since the cause of the interruption of the blood supply of the head of the femur in the hip joint is unknown.

The disease is most commonly found in children between the ages of 4 to 8 but it can occur in children between the ages of 2 to 15. The main long-term problem with this condition is that it can produce a permanent deformity of the femoral head which increases the risk of developing osteoarthritis in adults. It is also commonly known as Perthes disease, or Legg–Perthes disease. Because Perthes' disease is associated with certain clinical features more common in boys such as hyperactivity, small stature for age, delayed bone age, and some minor congenital anomalies, some call this Legg–Calvé–Perthes Syndrome to emphasize that the disease process may not be isolated to the hip joint only.

The name originated from the following people: Arthur Legg (1874-1939), an American orthopedic surgeon, Jacques Calvé (1875-1954), French orthopedic surgeon, and Georg Perthes, German orthopedic surgeon.^[2][3][4][5] The disease name was first described by Karel Maydl.

Signs and symptoms

Common symptoms include hip, knee (hip pathology can refer pain to a normal knee), or groin pain, exacerbated by hip/leg movement, especially internal hip rotation (twisting the leg toward the center of the body). There is reduced range of motion, particularly in abduction and internal rotation, and the patient presents with a limp. Pain is usually mild. There may be atrophy of thigh muscles from disuse and an inequality of leg length. In some cases, some activity can cause severe irritation or inflammation of the damaged area including standing, walking, running, kneeling, or stooping repeatedly for an extended period of time. In cases exhibiting severe femoral osteonecrosis, pain is usually a chronic, throbbing sensation exacerbated by activity.

The first signs are complaints of soreness from the child, which are often dismissed as growing pains, and limping or other guarding of the joint, particularly when tired. The pain is usually in the hip, but can also be felt in the knee ('referred pain'). In some cases, pain is felt in the unaffected hip and leg, due to the child favoring the injured side and placing the majority of their weight on the "good" leg. It is predominantly a disease of boys (4:1 ratio). Perthes is generally diagnosed between 5 and 12 years of age, although it has been diagnosed as early as 18 months. Typically the disease is only seen in one hip, but bilateral Perthes is seen in about 10% of children diagnosed. (The differential diagnosis for bilateral Perthes disease is Multiple Epiphyseal Dysplasia).^[6]

Cause

Legg believed the cause was impairment of blood supply to the femoral epiphysis, Calve believed rickets, and Perthes deduced an infection possibly causing degenerative arthritis leads to LCP disease. Currently, a number of factors have been implicated including heredity, trauma, endocrine, inflammatory, nutritional, and altered circulatory hemodynamics.^[7] Risk factors are not limited to impaired and disproportionate growth, low birth weight, delayed skeletal maturity, short stature, systemic hormonal changes and low economic index.^[8] Although no-one has identified the cause of Perthes Disease, it is known that there is a reduction in blood flow to the joint.

The disease is theorized to include the artery of ligmentum teres femoris being constricted or even blocked too early, not allowing for time when the medial circumflex femoral artery takes over. The medial circumflex femoral artery is the principal source of blood supply to the femoral head. LCP disease is a vascular restrictive condition of idiopathic nature. Symptoms like femoral head disfigurement, flattening and collapse occurs typically between ages four to ten, mostly male children of Caucasian descent. Children affected by LCP disease often display uneven gait, limited range of motion and they experience mild to severe pain in the groin area.^[9] For example, a child may be six years old chronologically but may have grown only four years old in terms of bone maturity. The child may then engage in activities appropriate for six years old child but lacking the bone strength of an older child, these activities may lead to flattening or fracture of the hip joint. Genetics do not appear to be a determining factor, but it has been suggested that a deficiency of blood factors with anticoagulant property used to disperse blood clots may lead to blockages in the vessels supplying the joint, but these have not been proven. It has also been suggested that there is a deficiency of protein C and protein S which also act as blood anticoagulants; if that were the case it is possible that their deficiency could cause clot formation in ligamentum teres femoris artery and hinder blood supply to the femoral head. However, there is no evidence of this; over the years many theories have been published but none have stood up to professional research.

Diagnosis

Radiograph of a person with LCP disease

X-rays of the hip may suggest and/or verify the diagnosis. X-rays usually demonstrate a flattened, and later fragmented, femoral head. A bone scan or MRI may be useful in making the diagnosis in those cases where x-rays are inconclusive. Usually, plain radiographic changes are delayed 6 weeks or more from clinical onset. So bone scintography and MRI are done for early diagnosis. MRI results are more accurate i.e. 97 to 99% against 88 to 93% in plain radiography. If MRI or bone scans are necessary, a positive diagnosis relies upon patchy areas of vascularity to the capital femoral epiphysis (the developing femoral head).

Treatment

The goals of treatment are to decrease pain, reduce the loss of hip motion, and prevent or minimize permanent femoral head deformity so that the risk of developing a severe degenerative arthritis as adult can be reduced.^[10] Assessment by a pediatric orthopaedic surgeon is recommended to evaluate risks and treatment options. Younger children have a better prognosis than older children.^[11]

Treatment has historically centered on removing mechanical pressure from the joint until the disease has run its course. Options include traction (to separate the femur from the pelvis and reduce wear), braces (often for several months, with an average of 18 months) to restore range of motion, physiotherapy, and surgical intervention when necessary because of permanent joint damage. To maintain activities of daily living, custom orthotics may be used. Over night traction may be used in lieu of walking devices or in combination.^[12] These devices internally rotate the femoral head and abduct the leg(s) at 45 degrees. Orthoses can start as proximal as the lumbar spine (LSO), and extend the length of the limbs to the floor. Most functional bracing is achieved using a waist belt and thigh cuffs derived from the Scottish-Rite Orthosis.^[13] These devices are typically prescribed by a physician and implemented by a orthotist. Clinical results of the Scottish Rite Orthosis have not been good according to some studies and the use of Scottish Rite Orthosis has gone out of favor. Many children, especially those with the onset of the disease before age 6, need no intervention at all and are simply asked to refrain from contact sports or games which impact the hip. For older children (onset of Perthes after age 6), the best treatment option remains unclear. Current treatment options for older children over age 8 include prolonged non-weight bearing, osteotomy (femoral, pelvic, or shelf), and the hip distraction method using an external fixator which relieves the hip from carrying the body's weight. This allows room for the top of the femur to regrow. The Perthes Association has a "library" of equipment which can be borrowed to assist with keeping life as normal as possible, newsletters, a helpline, and events for the families to help children and parents to feel less isolated.

While running and high impact sports are not recommended during treatment for Perthes disease, children can remain active through a variety of other activities that limit mechanical stress on the hip joint. Swimming is highly recommended, as it allows exercise of the hip muscles with full range of motion while reducing the stress to a minimum. Cycling is another good option as it also keeps stress to a minimum. Physiotherapy generally involves a series of daily exercises, with weekly meetings with a physiotherapist to monitor progress. These exercises focus on improving and maintaining a full range of motion of the femur within the hip socket. Performing these exercises during the healing process is essential to ensure that the femur and hip socket have a perfectly smooth interface. This will minimize the long-term effects of the disease. Use of bisphosphonate such as zoledronate or ibandronate is currently being investigated but definite recommendations are not yet available.^[14][15]

Perthes disease is self-limiting, but if the head of femur is left deformed there can be a long-term problem. Treatment is aimed at minimizing damage while the disease runs its course, not at 'curing' the disease. It is recommended not to use steroids or alcohol as these reduce oxygen in the blood which is needed in the joint. As sufferers age, problems in the knee and back can arise secondary to abnormal posture and stride adopted to protect the affected joint. The condition is also linked to arthritis of the hip, though this appears not to be an inevitable consequence. Hip replacements are relatively common as the already damaged hip suffers routine wear; this varies by individual, but generally is required any time after age 50.

Prognosis

Children younger than 6 have the best prognosis since they have time for the dead bone to revascularize and remodel, with a good chance that the femoral head will recover and remain spherical after resolution of the disease.^[16] Children who have been diagnosed with Perthes' Disease after the age of 10 are at a very high risk of developing osteoarthritis and Coxa Magna. When an LCP disease diagnosis occurs after age eight, a better outcome results with surgery rather than non-operative treatments.^[17] Shape of femoral head at the time when Legg-Calve Perthes Disease heals is the most important determinant of risk for degenerative arthritis; hence, the shape of femoral head and congruence of hip are most useful outcome measures.^[9]

Epidemiology

Perthes' disease is one of the most common hip disorders in young children, occurring in approximately 5.5 of 100,000 children per year. The lifetime risk of a child developing the disease is about 1 per 1,200 individuals. Boys are affected about 3-5 times more often than girls. New cases of Perthes' disease rarely occur after age 14 years (if diagnosed after 14 years of age, then it is usually old disease from early in childhood or avascular necrosis from an alternative cause).^[8] White northern Europeans appear to be affected more frequently than other races, though there is a paucity of reliable epidemiology in the southern hemisphere.^[18] Children of sufferers of the disease themselves may have a very slightly increased risk; though it is unclear if this is because of a genetic predisposition, or a shared environmental factor. It is most commonly seen in persons aged 3–12 years, with a median of 6 years of age. The UK incidence rates show an intriguing pattern with low incidence rates in London, and a progressive increase in disease in more northerly areas (maximal in Scotland).^[19] There is evidence to suggest that, at least in developed countries, more socioeconomically deprived communities have a greater risk of disease (a similar trend to diseases such as adult heart disease), though the reason for this remains unknown.^{[19][20][21][22][23][24]} One possible explanation that has been considered is tobacco smoke exposure, though this is significantly confounded by the strong socioeconomic gradient common to both smoking and Perthes' disease.^[8][25] Dietary factors of the child, and of the mother during pregnancy, are of interest to the research groups.

Other animals

LCP disease is an avascular necrosis of the femoral head in small breed dogs, usually those weighing less than 12 kg. LCP disease was first described in veterinary literature by Tutt in 1935.^[26] Tutt described the disease almost exactly what Waldenstromin (1909) described in humans.^[27] Small breeds, particularly Toy Poodles, Yorkshire Terriers, Pugs, Jack Russell Terriers, Westies and Dachshunds can be affected. There seems to be no sex predilection in the dog as contrasted to humans, in whom an 80% male incidence of the disease is evident. Similar to children, however, the condition is usually unilateral, with only about 10% to 15% incidence of bilateral disease. The age of onset varies between 4 months and 12 months, with a peak incidence at about 7 months.^[28] The pathology of avascular necrosis followed by revascularization and bony remodeling of the femoral head in the dog certainly suggests a vascular etiology even though the cause of the condition is not completely understood.^[29] Hip pain is usually seen by the age of 6 to 8 months.^[30] The disease is bilateral in 12 to 16 percent of cases.^[31] X-rays are necessary to make the diagnosis and show increased opacity and focal lysis in the head of the femur, and later in the disease, collapse and fracture of the neck of the femur. The recommended treatment is surgical removal of the head of the femur, but conservative treatment (rest, exercise restriction, and pain medication) may be effective in a limited number of cases (less than 25 percent, according to some studies).^[31] In dogs, the prognosis is excellent with surgery. Prednisolone tablets may also be helpful.

References

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External links

• Perthes Association (UK)- information about therapies, treatments and a comprehensive medical glossary in plain english
• International Perthes Study Group - a group of pediatric orthopaedic surgeons and researchers dedicated to the care of children with Perthes disease.
• Legg-Calvé-Perthes Disease The National Osteonecrosis Foundation
• Legg-Calvé-Perthes Radiology