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					Perthes' Disease
Perthes' disease is a condition where the top of the thigh bone (the femoral head) softens and
breaks down. It occurs in some children and causes a limp and other symptoms. The bone
gradually heals and reforms as the child grows. The aim of treatment is to ensure that the femoral
head reforms back into its normal shape so that the hip joint can work well.

What is Perthes' disease?
Perthes' disease is a condition of the hip which occurs in some children. It was first described in
1910 by three separate doctors and so it is sometimes called Calvé-Legg-Perthes disease after
each of these doctors.

What happens in Perthes' disease?
Perthes' disease occurs in a part of the hip joint called the femoral head. This is the rounded top
of the femur (the thigh bone) which sits inside the acetabulum (the hip socket). Something
happens to the small blood vessels which supply the femoral head with blood. So, parts of the
femoral head lose their blood supply. As a result, the bone cells in the affected area die, the bone
softens, and the bone can fracture or become distorted. The severity of the condition can vary.

Over several months the blood vessels regrow, and the blood supply returns to the bone tissue.
New bone tissue is laid down, and so the femoral head reforms and regrows. This is similar to
how bone reforms and regrows after any normal fracture or break to a bone. But, with Perthes'
disease, it takes longer (up to several years). The main concern with regrowth of the femoral
head is to ensure that it forms a good spherical (rounded) shape. This helps it to fit well into the
hip joint socket. If the femoral head is less rounded, hip movements may be affected and there
may be more wear and tear on the hip joint.

The exact cause of the blood vessel problem that occurs in the first place is not known. A child
with Perthes' disease is usually otherwise well.

Perthes' disease usually only affects one hip, but in about 1 in 6 cases it affects both hips (usually
at separate times).

Who gets Perthes' disease?
In the UK, about 1 in 1,000 children will get Perthes' disease. It occurs most commonly between
the ages of 4 and 8 years. About four boys are affected for every one girl.

What are the symptoms of Perthes' disease?
Symptoms tend to develop gradually and can include:

      A limp. This may gradually become worse over a few weeks.
      Pain in the hip and groin area. Sometimes pain is felt just in the knee or the thigh instead
       of in the hip - this is called referred pain.
      Stiffness and a reduced range of movement of the affected hip.
      In time, the affected leg may become slightly thinner (wasted) because the thigh muscles
       become thinner as they are not used so much as those in the other leg.
      The affected leg may look shorter than the good leg.

How is Perthes' disease diagnosed?
The diagnosis can usually be made by a doctor's examination of the hip, plus an X-ray (this is
usually an X-ray of both hips so that the two sides can be compared). Sometimes other tests may
be suggested if the diagnosis is not clear or if a more detailed picture of the hip joint is needed.
Possible tests may include: an MRI scan, a bone scan or an arthrogram (an X-ray where dye is
injected into the space within a joint). Also, blood tests, or a sample of fluid from the hip joint,
may be needed to rule out other problems such as infection.

What is the treatment for Perthes' disease?
The aim of treatment is to promote the healing process and to ensure that the femoral head
remains well seated in the hip socket as it heals and regrows. Which is the best treatment can
depend on the age of the child and the severity of the condition. Treatments may include
observation, bed rest and/or crutches, a plaster cast or special leg brace, or surgery. Your doctor
will advise on the best treatment for your child.

Observation and physiotherapy

In younger children (under 5 years old), and those with mild disease, Perthes' disease will usually
heal well without any specific treatment. These children are treated by observation, often with
physiotherapy or home exercises. The home exercises help to keep the hip joint mobile and in a
good position in the hip socket. Advice may also include to encourage swimming (to keep the
hip joint active in the full range of movements) but to avoid activities that can lead to heavy
impact on the hip joint, such as those involving trampolines and bouncy castles. However, any
advice will be tailored to your child's needs. Your child will also need regular follow-up with
their specialist to check how their femoral head is healing. Regular X-rays of their hips are
usually suggested.

Painkillers may also be useful to help relieve pain. Common painkillers suggested are ibuprofen
and paracetamol.

Bed rest and/or crutches

This may be needed by some children for a short time if their symptoms are bad.
Plaster casts or a special brace

These may be considered in some cases. The aim is to keep the femoral head well positioned in
the hip socket. The cast or brace usually helps to keep the leg slightly abducted (slightly pointing
outwards). The special braces are also called orthotic devices. With many of these, the child is
able to walk and weight bear, but the braces usually need to be worn for many months. The
success of brace treatment is not entirely clear, and many doctors are increasingly advising
surgery.

Surgery

An operation may be considered in some cases, particularly in older children or those more
severely affected. Surgery can help to keep the femoral head well positioned whilst it heals, or
can improve the shape and function of the femoral head if it has not healed well. There are
various options, depending on each child's individual situation. If surgery is being considered,
you should discuss the options fully with your child's surgeon.

What is the outcome (prognosis)?
In many cases, the femoral head regrows and remodels back to normal, or near-normal. The hip
joint then returns to normal and is able to work as usual. However, it can take two or more years
after the condition first starts.

The main concern is that the femoral head does not reform properly. Flattening of the femoral
head can occur in some cases and this can lead to a permanent change in the hip joint. This may
cause stiffness of the hip joint. It can also cause arthritis of the hip joint at an earlier age than
usual - for example, at around age 40. Sometimes, a hip replacement is needed as treatment for
arthritis.

Things which may affect outcome include:

      Age. The younger the child is when Perthes' disease develops, the better the chance of a
       good outcome. This is because there is longer time for the hip to remodel before the child
       finishes growing. Children who develop Perthes' disease after about the age of 8-9 have
       the highest risk of permanent hip joint problems, such as stiffness and arthritis; there is
       less time for the hip to remodel before they finish growing.
      Gender. For any given age when the condition develops, boys have a better chance of a
       good outcome than girls. This may be because girls tend to finish growing a bit earlier
       than boys.
      Severity. The more severe the condition (which can be judged by the X-ray pictures of
       the hip), the greater the risk of permanent problems with the hip joint.

Cause
Legg believed the cause was impairment of blood supply to the femoral epiphysis, Calve
believed Ricketts, 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. [5] 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. [6] 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 femoral circumflex artery is the principle 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. [7][citation needed]
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 proteins C and 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.

Signs and symptoms
Common symptoms include hip, knee, or groin pain, exacerbated by hip/leg movement. The pain
is moderate to severe, at times rendering the patient unable to stand. There is a reduced range of
motion at the hip joint and a painful or antalgic gait. 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[citation needed], 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 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 Bi-lateral Perthes disease is
Multiple Epiphyseal Dysplasia). [8]
Diagnosis
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. Neither bone scan nor MRI offer any
additional useful information beyond that of x-rays in an established case. 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 goal of treatment is to avoid severe degenerative arthritis. Orthopedic assessment is crucial.
Younger children have a better prognosis than older children.

Treatment has traditionally centered on removing 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. [9] 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.[10] These devices are
typically prescribed by a physician and implemented by a certified orthotist. For older children,
the distraction method has been found to be a successful treatment, 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. Many children need no intervention at all and are simply asked to refrain from contact
sports or games which impact the hip. 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.

Modern treatment focuses on removing pressure from the joint to increase blood flow, in concert
with physiotherapy. Pressure is minimized on the hip through use of crutches or a cane, and the
avoidance of running-based sports. 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 zoledronic acid has also been investigated.[11]

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[citation needed].

Incidence
Perthes is one of the most common hip disorders in young children, occurring in approximately
5.5 of 100,000 children per year (and therefore a lifetime risk of a child developing the disease is
about 1 per 1200 individuals). Male to female ratio of occurrence is 3 - 5:1. Most cases of
Perthes disease have presented themselves by age 14 years old. [6] Caucasians are affected more
frequently than other races[12] . Children of sufferers of the disease themselves have a very
slightly increased risk; 1 in 100 male children of adults with Legg–Calvé–Perthes syndrome also
exhibit the syndrome. It is most commonly seen in persons aged 3–12 years, with a median of 6
years of age.[citation needed] 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)[13]. Maternal cigarette smoking adds confounding factors beyond biological and
environmental. Maternal tobacco smoking was said at one time to be another significant risk
which carried a risk five times higher than those not exposed to smoking. This has since been put
to one side as there is no clear evidence of this. [6]

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. [14] 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. [15] 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.[7]

Legg–Calvé–Perthes disease in dogs
Osteonecrosis of the femoral head of young, small breed dogs (LCP disease) was first described
in veterinary literature by Tutt in 1935:[16] he described the disease, as did Waldenstromin (1909)
in humans,[17] Toy and small breeds, particularly Toy Poodles, Yorkshire Terriers, Pugs, Jack
Russell Terriers, and Dachshunds can be affected. LCP disease is an osteonecrosis of the femoral
head in small breed dogs, usually those weighing less than 12 kg. 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. As in 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. [18] 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. [19] Hip
pain is usually seen by the age of 6 to 8 months.[20] The disease is bilateral in 12 to 16 percent of
cases.[21] 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).[21] The prognosis is excellent with
surgery

				
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