The Perthes disease or Legg-Calve-Perthes disease is a rare condition that manifests itself in childhood and affects the balance. It occurs when the blood supply to the head of the femur (thigh bone) is interrupted, without a known cause. Without proper blood supply, bone cells die, a process called avascular necrosis Even though the disease can affect children of any age, it most commonly occurs in boys between the ages of four and eight years (the condition is five times more common in boys than in girls) and the healing time can last 2 years or even longer.

White children are more likely to develop this condition compared to black children and in a small percentage, the condition is transmitted hereditary.

The disease affects the balance in several stages.

In the first stage, the lack of vascularization of the femoral head occurs. This causes bone cell death, a process called osteonecrosis or avascular necrosis.

In the second stage, softening and deformation of the femoral head occurs.

In the third stage, the bone tends to recover to some extent, over a period of 2 years.

During this time, children adapt their gait or find other ways to move

The hip joint is the largest and most mobile joint in the body and consists of:
➢ The spherical head of the femoral bone which represents practically about 2/3 of the joint
➢ The acetabular or glenoid cavity (part of the coxal bone) in which the femoral head is fixed Basically, the hip joint connects the femur (thigh bone) to the pelvis.
The femur, the largest bone in the body (in adults it measures 40–50 cm), has at its upper extremity the femoral head, which is connected to the body of the femur by means of the femoral gap. At the union of the femoral gap with the femoral body there are two protrusions, called the big trochanter and the small trochanter. These protrusions of the bone(trochanters) allow the muscles to attach to the bone. The big trochanter is the place where the buttock muscles meet and perform the abduction movement of the hip (bringing the lower limb to the side)
The small trochanter is the place where the iliopsoas muscle is attached to the hip joint to ensure the flexion movement of the hip (raising the lower limb in front).
The blood supply to the hip joint comes directly from the femoral artery (a major blood vessel that comes from the aorta).

If the pain is intense, a short period of bed rest accompanied by light tractions can help significantly. Traction is a constant and gentle pulling force of the lower limb.

As the hip becomes stiff, the ligaments and muscles around it may become shorter. Thus, under the supervision of a physical therapist, stretching exercises and toning exercises of the muscles around the hip will be performed, in order to keep it flexible and stable.

In certain situations, any weight or stress in the affected hip should be avoided, which is why the use of crutches when walking becomes an option.
Crutches will help protect the joint from any undue pressure.
In other situations, in order to keep the femoral head well fixed in its place (in the acetabular cavity), it may be necessary to wear an orthosis or other orthopedic device, which keeps the hips in flexion and abduction, for a period of 4-6 weeks.

It is recommended in case of severe deformity or in the case of children over the age of 7 years. Under the age of 7, children's bones are much easier to "shape" with the help of conservative (non-surgical) treatment

In the long run, the shape of the hip joint can be changed and this can lead to early arthritis many years later.

Avoid high-impact activities such as jumping or running, as they can accentuate the damage suffered by the already weakened bone.