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Health

Orthopedic Surgeries in the Technological Vanguard

May. 10 de 2012

By: Elizabeth Vera Martínez, Unimedios

X-rays and other advanced imaging technologies provide specialists with the most accurate possible information on the part of the skeleton to be surgically treated. Now, a three-dimensional computer modeling tool and a prototype adapted to each patient will make it possible to carry out such surgeries with greater precision and in less time.

Skeletal deformations can produce pain and affect a person's physical performance. Diagnostic imaging such as x–rays, computerized axial tomography and magnetic resonance allow orthopedists to identify and locate the precise areas of these alterations, helping them to plan the needed surgical correction (osteotomy).

The osteotomy consists in cutting the bones to modify their form and orientation, as explained by specialist Carlos García Sarmiento, an orthopedist at the Universidad Nacional de Colombia (National University of Colombia), who points out that in this manner the deformation is repaired in order to relieve pain and improve the patient’s affected parts.

Skeletal imperfections can be congenital (at birth) or acquired, due to fractures, degenerative processes such as aging and excessive weight.

The Biomechanical Research Group at the Mechanical and Mechatronical Engineering Department, led by Professor Carlos Julio Cortés Rodríguez, with participation by engineers Mauricio Cuervo, Óscar Rodríguez and Indy Araque, is developing an innovative physical prototype for surgical planning, which focuses on the affected part of the patient's body through computerized three–dimensional modeling.

This technology is an important medical tool that offers greater orientation, safety and precision during a surgical intervention, according to specialist García.

Pelvic region

During the first years of life, the pelvis is made up of the Ilion bones (large and flat) and the ischium bones (round and curved, which help to support the body's weight when seated) and the pubis (which joins together the two sides of the pelvis). These are slightly separated and, as the person grows, become joined together to form what in adults is referred to as the coxa and which, along with the sacrum, make up the pelvic region.

The pelvis is therefore a ring-like structure that, if fractured in a certain place or if its segments are separated, produces a fracture or luxation in another place.

The hip is made up of two bone structures, one known as the acetabulum (a spherical cavity in the pelvis) and the other as the femoral head (a massive sphere at the end of the femur). Its joint makes possible the movement of the inferior members, the forward movement of the human body and enables the body to support its own weight. Improper fit between these two parts results in pain and limping.

Until now, using imaging technologies, physicians have been able to see the location of fractures or other deformations, but the work of the Biomechanical Group goes further.

“This tool incorporated by the engineers at the National University is innovative in our field because it enables surgeons to have a physical prototype similar to the bony structure prior to surgery. Thus, we are able to approach the area that must be cut or modified with greater precision”, says the orthopedist.

Rapid prototyping

Based on three-dimensional modeling software, a customized database is created called Dataset, into which all of the patient's data and pathology is introduced, explains Professor Cortés Rodríguez. “The idea is that this program, once the complete and precise information is received, creates a physical impression of the particular osteal system”.

At that point in the process, the specialist can use the computer to observe the condition of the bone in all its angles (three-dimensional form). With this technology, the information is exported through a special format, called STL (program), which is used to physically create the required prototype.

The model is generated through additive production by layers (rapid prototyping), similar to a “three-dimensional impression”, that creates the specific part of the human body using polymeric material with textures and colors similar to the real tissues. For orthopedist García Sarmiento, the product of this impression, in other words, the bony structure copied from the patient, facilitates manipulating and becoming familiar with the situation before the surgery.

“The additive manufacturing technique by layers is able to clearly reproduce the details, with geometries that would be impossible to imitate using conventional processes”, according to Professor Cortés Rodríguez.

Advantages

Using the physical sample of the osteal structure or of the region of interest, which contains a representation of the bony tissue from each of the patient’s scanned axial cuts, a specialist can guide his approach and see the exact morphology that he will have to deal with. He can thus shorten the duration of the operation while improving the probability of a successful surgery.

“The solid three–dimensional models make it possible for these surgeries to be constantly improved, because diagnostic imaging by itself frequently does not facilitate the characterization of a deformation”, says this specialist at the National University, who successfully tested the technique last year on a child with hip dysplasia. This congenital anomaly occurs because the acetabulum and the head of the femur are not correctly joined, thus producing pain and skeletal alteration.

“The technique has shown itself to be very valuable in complex surgeries, insofar as simple interventions such as luxations of the bones of the fingers, hands or feet are sufficiently well managed through imaging”, said Professor Carlos García.



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