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Segmental Instrumentation Surgery
Relevant information about Segmental Instrumentation Surgery.
Segmental Instrumentation is a surgical procedure that consists on inserting different kinds of instrumentations made of metal, usually titanium, into the spinal column to support a Spinal Fusion. This is done in order to treat deformities of the spinal column, due to birth defects, fractures, scoliosis, herniation, and other injuries or spinal diseases. The instrumentations can include pedicle screws, rods, plates, intervertebral cages, hooks and rods. It is expected that after the whole procedure, the spine will fuse with these, recovering its stability and strength. Depending on the location of the problem treated, the instrumentation type will vary.
There are two main problems which can be solved by this type of operation. These are herniated disc and spinal instability. A herniated disc, also called prolapsed disc, may happen when due to a big pressure, a spinal column disc bulges out from between two vertebrae, thus compressing the spinal canal. When the herniated disc is in the lumbar or thoracic region, this will cause sharp and continuing back pain, a weakening of the muscles in the leg, and some loss of sensation in the leg and foot. In addition, it may also be difficult to raise the leg when it is held in a straight position. If the herniated disc is in the cervical region it will cause neck pain, stiffness, and numbness and weakness in the arms or hands. Spinal Instability happens when the spinal column with its ligaments and muscles lose their stability, becoming lax, and finally leading to abnormal weakness in certain areas. This instability will cause pain and injury to the spinal cord and nerves, which can also cause neurological symptoms. These problems may happen for two different types of causes. The first type is deformity in the spinal column caused by disease. The second type is injury in the spinal column caused by trauma. Both causes may generate a herniated disc or spinal instability.
The operation usually divides itself in two parts. The first part is a Spinal Fusion, which is necessary to eliminate the spinal column deformities. The second part involves the instrumentation that will be used to support the fusion. In addition, there is a previous step in which the type of instrumentation is defined, by considering variables like posterior or anterior position and the zone and type of problem treated. The Spinal Fusion begins with the patient being put in a position that is suitable for the specific type of instrumentation that has to be done. Then, an incision is made in the zone that has to be treated. The muscles and nerves are put aside, in order to allow reaching the spinal column. Once the spinal column has been reached, flaps are sliced in the vertebrae of the problem zone. Next, the bony outgrowths that allow the spinal column to twist and bend are removed. Bone grafts are then put vertically across the exposed surface of the cut vertebrae. All the bone grafts used must also touch adjoining vertebrae. After this is done, the flaps are folded back to their original position, covering the bone grafts. It is expected that the grafts will grow into the bone and fuse the vertebrae together. The instrumentation part of the procedure tends to vary, depending on the type of device used. However, the general procedure tends to be usually the same. In order to support the fusion of the vertebrae, the device, that usually has one or more steel rods, is extended from the bottom to the top of the treated area. Then it is attached by hooks that are suspended by pegs inserted into the bones. Finally, the device is jacked up and locked in order to correctly support the spinal column. After this, the muscles and nerves are put back in place and the skin is stitched together.
During the post surgery patients usually have to wear a full body cast. Also they may have to lie in bed for at least three months after the procedure. This time can be extended until six months. Additional precautions may be taken, depending on each patient’s particular case and the type of instrumentation done.
Two main complications can happen. First of all, if the fusion fails to heal, a pseudoarthrosis may be developed. This happens when a false joint develops on the treated site causing pain symptoms. The other complication is disc degeneration. This happens when the stress generated by the fusion in the lower back is too big and damages the lower spinal column discs. This can cause pain symptoms and instability. Both complications are rare.
The treatment allows a damaged Spinal column to recover stability, strength and eventually to regain mobility.
The instrumentation cannot correct the problem without fusing a part of the spinal column that will be reduced and lost. Also, the device is usually not removed from inside the patient.
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