Over 100 years have passed now since Drs. Legg, Calvé, and Perthes first described a hip condition in children now referred to as Legg-Calvé-Perthes (LCP) disease. In those 10 decades, three things have become much clearer: what causes the problem, who is affected, and which treatment approaches work best.
In this condition, the blood supply to the growth center of the hip (the capital femoral epiphysis) is disturbed, causing the bone in this area to die. The blood supply eventually returns, and the bone heals.
How the bone heals determines what problems the condition will cause in later life. Perthes disease may affect both hips. In fact, 10 to 12 percent of the time the condition is bilateral (meaning that it affects both hips). This condition can lead to serious problems in the hip joint later in life.
Clearly the problem is one of blood loss called ischemia. The area affected most is the head of the femur (thigh bone). This has been confirmed with today’s modern imaging studies. As a result of this blood loss, the bone dies and starts to collapse. Soon the smooth, round head of the femur starts to flatten and deform.
X-rays helped in the early days of discover to rule out tuberculosis as a possible cause of the hip pain, limp, and loss of motion that accompany Legg-Calvé-Perthes (LCP) disease. It was quickly realized that faulty delivery of blood to the hip was the cause of LCP.
But even with today’s modern imaging tools, the exact vascular (blood supply) problem is unknown. Two theories are currently being investigated: arterial infarction and venous congestion. Arterial infarction refers to blockage of the blood vessels bringing oxygenated blood to the hip. Venous congestion describes a condition in which blood reaches the area but doesn’t return quickly to the heart. Instead, blood pools in the area.
X-rays have also made it possible to classify or “stage” the disease based on severity. But agreement is lacking on the best way to classify LCP. Currently, surgeons are working backwards to identify early stages of the condition and find ways to predict outcomes.
By working backwards, we mean they are looking at the medical records and results of treatment for adults who had this condition as a child. Then they take a look back over the years at X-rays, MRIs, and clinical reports. By seeing the end results, reviewing treatment given and early findings, scientists are able to make better plans for early treatment of children today with Legg-Calvé-Perthes disease.
For example, in this study, X-rays and MRIs of the femoral head deformities seen in adults were compared to the same findings reported in childhood. This type of study technique is called end-result radiographic analysis.
Using this method, they developed a more reliable classification system called the lateral pillar classification. The lateral pillar is seen on X-rays as changes on the outside edge of the femoral head. The classification scheme labels changes in four categories (A, B, B/C, and C) to represent severity from A (mild) to C (severe).
Changes along this side of the femoral head seem to be able to predict final outcomes. Comparing imaging results with treatment applied for each category allowed orthopedic surgeons to see that there was no difference in results based on the treatment applied. So for example, no changes were observed in the lateral pillar after bracing, range-of-motion exercises, or even after no treatment.
The older children (over eight years old) who had surgery to correct the problem were the most likely to have better restoration of the lateral pillar deformity as seen later in adulthood. This was true for mild-to-moderately severe femoral head deformities. Severe lateral pillar changed did not respond better to one type of surgery over another.
The authors came to several conclusions based on the results of this comparative study. First, some children can be spared the discomfort of bracing and even the risks of surgery. Who are these children? Can they be identified ahead of time? They are the patients who have mild changes of the lateral pillar diagnosed before age eight.
Second, something more must be done to successfully treat the severe lateral pillar deformities. Surgery doesn’t really seem to help, so why put these children through that step?
And finally, it is suggested that when the exact vascular problem causing Legg-Calvé-Perthes (LCP) is discovered, then perhaps a more effective treatment can be found. There is plenty of room in the future for research around this problem.