Core Decompression

The Core Decompression method was developed in Portugal by Dr. Nuno Lopes. It is also referred to as a trans-neck-head tunneling (TNHT). He has used it for over 20 years and has drilled over 200 hips. This technique involves making a 5mm hole with a drill, or a device called a trephine, from the femur, up the femoral neck, across the growth plate, and into the center of the dead bone within the femoral head. The function of the growth plate (physis) of the upper femur is to cause the femoral neck to grow in length, adding to the length of the femur. The growth plate acts as a barrier to blood vessel communications between the bone of the upper femur and the femoral head and neck. When there is a loss of flow from the arteries entering the femoral neck, the rest of the femur cannot provide blood flow to the femoral head because the growth plate acts as a barrier. In adults, the growth plate closes and disappears, allowing blood circulation between the two parts of the femur. By drilling a hole through the growth plate, a portal of communication is opened between the rest of the femur and the avascular femoral head. The blood vessels from the upper femur grow through the hole in the growth plate to resupply circulation to the avascular femoral head.

An example of a core decompression

 

Dr. Lopes has observed that drilling leads to more rapid reconstruction of the femoral head in early Perthes. Using MRI and ultrasound to screen patients at risk, he has identified a pre-Perthes stage of disease. He claims that core decompression at this very early stage can lead to complete resolution of the problem and avert the resorption and re-ossification phases of Perthes. His indications for this procedure are children with whole head involvement who are identified at the pre-Perthes stage (MRI changes only) or very early Perthes stage. According to Lopes, this method is almost universally successful at the pre-Perthes stage and about 50% successful at the early Perthes stage, such that no further surgical treatment is required. Dr. Paley has been using this method since 2001, with results similar to those reported by Dr. Lopes. External bracing is indicated after core decompression to protect the fragile head. The attractive aspect of core decompression is that it is minimally invasive and technically simple for any orthopedic surgeon to perform. In adults, like in children, drilling only works well in the very early stages of the disease.

Dr. Lopes's results with core decompression:

  • 123 cases between 1971-2006
    • Speeds time of remodelling by 50%
    • 17% needed additional surgery

Dr. Paley's results with core decompression:

  • 23 cases between 2000-2005
    • Speeds time of remodelling by 50%
    • 15% needed additional surgery

Since this 2005 study, more than 100 patients have received a Core Decompression surgery at the Paley Institute. We continue to perform this surgery with excellent results.

The main risks of core decompression are fracture and growth arrest of the femoral neck. However, since the hole diameter is small compared to the overall cross-section of the neck, the risk of fracture is minimal. Neither Dr. Lopes nor Dr. Paley has experienced any fractures after core decompression. Growth arrest of the proximal femoral growth plate can occur if a bony bridge develops across the drill channel, joining the femoral head and neck with the upper femur bone thus tethering further growth. If a bridge develops, it can stop the growth of the upper femur, or if it is too near the edge of the growth plate, this can also lead to a deformity since one side of the growth plate will continue to grow while the other side might be arrested. Dr. Lopes’s research has shown that as long as the drill hole is less than 10% of the area of the growth plate, then the growth plate will not stop growing. Our results are too few to comment on this, but we remain vigilant to this potential complication to an otherwise minimally invasive surgical method.

It is important to note that closure of the growth plate of the femoral neck is a recognized and common complication of Perthes disease, even when no treatment is performed. Therefore it may be difficult to separate growth arrest due to drilling versus growth arrest due to the disease itself. We believe that core decompression is a promising treatment that may have an expanded role on its own or in conjunction with other treatments.

Patient Case Study: Perthes Disease w/ Core Decompression & Distraction Treatment

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