Perthes disease

Perthes disease

Perthes disease, or Legg-Calvé-Perthes disease, is a non-infectious condition characterized by the death of the femoral head bone. The predominant age of onset for Perthes disease is between 4 and 14 years old, with boys being affected 3 to 4 times more often than girls. It represents the most common type of aseptic necrosis of the femoral head in childhood.

Perthes disease progresses through five stages:

  1. Stage 1 – Aseptic necrosis
  2. Stage 2 – Secondary compressive fracture
  3. Stage 3 – Fragmentation and absorption of areas of dead cancellous bone
  4. Stage 4 – Revascularization
  5. Stage 5 – Stage of secondary changes

Causes

The development of Perthes disease requires certain predisposing (congenital) and inducing (acquired) factors. A predisposing factor for Perthes disease is the underdevelopment (hypoplasia) of the lumbar spinal cord, which innervates the hip joints. Spinal cord hypoplasia has a congenital, hereditary basis and can vary in severity. It is often associated with a range of orthopedic conditions, including Perthes disease.

The anatomical structure of the hip joint area in children with spinal cord hypoplasia is characterized by fewer and smaller blood vessels and nerves, leading to chronic decreased blood flow and nutritional deficits in the joint tissues. Additionally, spinal cord hypoplasia negatively affects vascular tone.

Perthes disease develops when blood supply to the femoral head is completely interrupted due to inducing factors such as inflammation of the hip joint or minor trauma, leading to compression of the few and underdeveloped vessels from the outside. Inflammation of the hip joint can occur due to infection, for example, from the upper respiratory tract during colds. Minor trauma may go unnoticed by both parents and children. This results in complete blockage of blood flow (or infarction) to the femoral head, leading to partial or complete necrosis, or the formation of a necrotic lesion.

Symptoms

The disease often affects one side, less commonly both sides. Initial stages may be asymptomatic. The first signs of Perthes disease include mild pain in the hip joint and limping. Sometimes the disease begins with pain in the knee joint. Parents may notice gait abnormalities such as limping or dragging one leg. Severe pain is less common, and severe limping is usually absent, making early medical consultation in the first stage of the disease (osteonecrosis stage) relatively rare.

Subsequently, the necrotic bone tissue of the femoral head loses its normal mechanical strength, leading to the gradual development of hip joint deformity under the influence of normal daily activities such as walking and jumping, or even in the absence of such activities. Later symptoms include fatigue during walking, joint pain, limping, restricted hip joint movement, and limb shortening.

By the end of Perthes disease, the degree of femoral head deformity can vary from slight and barely noticeable on X-rays to gross “mushroom-shaped” or “saddle-shaped” deformities. The degree of deformity is determined by the size and location of the necrotic lesion in the epiphysis and directly determines the outcome of the disease – whether it is favorable or unfavorable. An unfavorable outcome of the disease is considered the appearance of clinical signs of deformative coxarthrosis (progressive degenerative joint changes) in the form of pronounced pain syndrome and gait disturbances.

Diagnosis

The necessary minimum examination to confirm or exclude Perthes disease, even in its earliest stage, is radiological imaging. Magnetic resonance imaging (MRI) and ultrasound of the hip joints may also be recommended as additional diagnostic methods but are not definitive for diagnosing Perthes disease.

Treatment

The primary goal of treating children with Perthes disease is to restore the affected hip joint’s anatomy to as close to normal as possible. This approach aims to minimize gait disturbances and pain throughout the patient’s life.

Conservative measures form the basis of treatment for children with Perthes disease:

  • Ensuring containment of the femoral head (complete “submergence” into the acetabulum) using orthopedic devices such as functional braces (Mirzoyeva or Vilensky brace), plaster casts (Lang’s brace or coxal bandage), traction applied to the thigh or leg (adhesive, skeletal, or cuff traction).
  • Therapeutic exercises, massage, and physiotherapy procedures with angio-protective effects.
  • Medication therapy including osteoprotectors and chondroprotectors.
  • Surgical intervention is indicated for stages 2-3 of the disease and aims to improve blood supply to the femur and correct biomechanical abnormalities in the joint resulting from femoral head deformity.

The overall duration of treatment typically spans 3-4 years.