Operational preparation | Intervertebral disc prosthesis

Operational preparation

The most important thing in the preparation for the operation of the disc prosthesis is the correct indication. For this purpose, in addition to the physical examination, above all imaging examination procedures are necessary. On x-rays a disease of the intervertebral disc can be diagnosed.

Although the intervertebral disc itself is not visible on an x-ray, a reduced distance between two adjacent vertebral bodies indicates a reduced-height and thus diseased disc (chondrosis). Irregularities in the cover and base plates as well as bone densification of the adjacent vertebral bodies indicate the involvement of the vertebral bodies in the disease process (osteochondrosis). X-rays also provide indications of reduced bone density or instability of the vertebral bodies among themselves.

Lateral x-rays show a vertebral body offset in the latter case. Sometimes, however, functional X-rays (X-rays in maximum forward and backward flexion) are necessary to demonstrate a vertebral body offset and thus instability. As already mentioned, severe instability or osteoporosis is a contraindication for the implantation of a disc prosthesis.

Magnetic resonance imaging of the cervical or lumbar spine has become indispensable in the diagnosis of spinal diseases. In contrast to x-rays, the disc itself, but also all other important structures of the spine can be assessed. A disease of the vertebral body joints (spondylarthrosis) is detected, as well as a narrowing of the spinal canal (spinal stenosis).

Both diseases are contraindications for the implantation of a disc prosthesis. The MRI of the lumbar spine / cervical spine (magnetic resonance imaging) is therefore the best imaging method for the diagnosis of spinal diseases. What MRI (magnetic resonance imaging) cannot do, however, is to establish a relationship between the image findings (e.g. a diseased intervertebral disc) and the patient’s symptoms.

This means that a diseased intervertebral disc can be the cause of back pain, but does not have to be. On the contrary, most patients with wear-related changes in the intervertebral discs are free of complaints. A discography is a minor surgical procedure, which is only performed under local anaesthesia of the patient.

It is a diagnostic procedure that requires the cooperation of the patient. A thin needle is used to inject a contrast medium into the disc and then an X-ray image is taken. In this way, the disc tissue can be precisely imaged and damage can be made visible.

Above all, however, the injection serves to secure the diagnosis in case of suspected disc-related (discogenic) back pain. The injection of the contrast medium causes an increase in pressure in the disc space, which leads to a provocation of pain. The patient should feel exactly the pain he/she is familiar with during the injection and should tell the doctor so.

If this is the case, one speaks of a positive distension test. If no pain is provoked, the distension test is negative and the cause of the back pain remains unexplained at first. A disc prosthesis implantation will then be omitted.