PERTHES DISEASE
THE PHASES OF PERTHES
DIAGNOSIS
THE CAUSE
SYMPTOMS
A majority of sources agree that there are four stages or phases that occur during Perthes, these occur over various time periods and can overall take a number of years to heal:
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PHASE ONE: Necrosis
Where the blood supply to the femoral head is interrupted. During this stage the hip joint becomes inflamed, stiff and painful. Increased density of the femoral head occurs which can lead to fractures in the bone. This phase can last from several months up to one year. Due to the lack of blood, ‘portions of the bone turn into dead tissue’, this can cause the femoral head to loose its rounded shape when seen on x-rays.
PHASE TWO: Fragmentation​
After the death of the bone cells, the processes of fragment and reabsorption occur, the dead cells are ‘gradually and irregularity absorbed by the body, giving rise to fragmentation, on x-rays the head has a broken up appearance. Then the body replaces the dead bone cells with new, healthier bone cells. This phase can last from one to three years.
PHASE THREE: Re-ossification​
This is where the femoral head beings remodelling to its original rounded shape with new bone, this phase can last for one to three years.
PHASE FOUR: Remodelling
This stage can take years to complete as this is where the healing process is completed. Normal bone cells replace the new bone cells and the remodelling continues allowing the femoral head to reshape, although usually oval rather than a perfectly rounded shape.
Perthes Disease is idiopathic, meaning the cause is unknown, and no known preventative measure, although there are many contradicting theories, possible risk factors, and known negative causes.
What can be determined is that more research is needed to unlock the biological etiology of the disease.
THEORIES:
Posible theories that may be the cause of Perthes, however these theories can be contradictory:
- subtle problem with blood clotting
- secondary smoke
- traumatic injury to the femoral head
- poor diet
- poor health
- poor living conditions
- in this age group there is a chance of interrupting blood vessels due to development of the femoral head.
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POSSIBLE RISK FACTORS:
A key finding that was found in a number of sources is the view that there is increased risk for children who are:
- small for their age
- extremely active
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FACTORS THAT ARE KNOWN NOT TO BE THE CAUSE:
- Perthes is not due to infection.
- Perthes is not due to injury or general blood vessel problem (which could be classified as contradicting two theories).
- Perthes is not a genetically occurring disease, although it has occurred in more than one generation of a family and in siblings, these are exceptions due to chance.
Symptoms of Perthes range from individuals, some patients experience pain while for others it is painless. The most common symptom is a limp which becomes more apparent after physical activities. Some children also experience hip or groin pain, and even referred knee or shin pain. Overall there is a loss of the child’s range of movement of the hip.
The Diagnosis of Perthes is straightforward, if diagnosed correctly a GP will usually refer the patient to a specialist, such as an orthopaedic surgeon. The most common way of determining the disease is by having a number of x-rays over a period of several months, these x-rays will typically show a flattened femoral head. Bone scans and MRI (magnetic resonance imaging) can be done if x-rays return as negative, especially in the early stages of the disease.
GENERAL INFORMATION
Perthes disease, also known as Legg-Calve-Perthes is a form of osteonecrosis of the hip only found in children.
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Perthes was discovered around 1910 by three individual doctors, Dr Arthur Legg (An American orthopaedic surgeon), Jacques Calvé (A French orthopaedic surgeon) and Georg Perthes (A German orthopaedic surgeon).
Perthes Disease affects children, although the precise age group when it can occur is disputed among specialist, opinions ranging form 2 – 15 years.
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It is more common in boys than in girls, with roughly four times more boys diagnosed than female patients. As as expected Perthes is mostly a unilateral disease, however there is a small percentage of patients that Perthes occurs bilaterally; either at the same time or later on in the unaffected hip.
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Although it is agreed that Perthes is rare, the exact statistics are not consistent ranging from 1 in 1200 children to 1 in 20000 children.
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Races that are at greater risk of the disease are Caucasians, Asians and Eskimos. It is less common in Indigenous Australians and Americans, Polynesians and Negroid races.
