Prosthetics of the intervertebral disc is a complicayed method of state-of-art surgical invasion that allows removing an intervertebral disc and replace it with a prosthesis.
The prosthetics surgery can be made with a half-open (endoscopic) method, or with the help of open invasion. The implant is installed once, and can serve till the end of patient’s life. Full life cycle of an artificial intervertebral disc is up to 20 years and more. When this period is over, the prosthesis is self-blocked, and it becomes an immobile cage. As a rule, it happens in mature-aged patients, when stiffness of neck develops.
The main indication for prosthetics of intervertebral disc is spinal hernia with nerve entrapment caused by degenerative changes of intervertebral disc. Prosthetic surgery is also prescribed in the following cases:
- osteochondrosis vertebralis;
- durable low back pain that is localized between the 12th pair of ribs and gluteal furrows;
- damage of structure of vertebral disc, loss of its height;
- narrowing of radicular foramen of the spinal cord (foraminal stenosis).
Prosthetics of intervertebral disc allows to:
- eliminate pain;
- save mobility of the spinal cord and improve life quality;
- take a long-term effect from treatment;
- restore work productivity and get back to normal lifestyle quickly;
- continue doing sports and exercising.
Modern prosthesis of intervertebral discs have natural physiology and can restore mobility of the spinal cord in six directions, including crunching and stretching. They imitate the anatomy of human spinal disc perfectly and have all required biochemical characteristics. Besides, their form and material features allow saving the adjacent vertebrae and fix them strictly. This is why artificial disks are not rejected by patient’s body, and rehabilitation does not require much time.
A prosthesis of intervertebral disc is produced from titanium and polymers. Today, new kinds of bioprostheses are used successfully: their features are close to organic human tissues. The implant has two movable hinges, and its exterior plates replicate the form of vertebrae to which the artificial disc will adjoin. Inside the prosthesis, a movable nucleus is placed, and it allows for movement of the new joint in all directions. All elements of the device replicate functions of the fibrous ring and nucleus pulposus of the natual intervertebral disc.
Intervertebral implants can differ depending on the material, which defines the area where the device will be used, and its advantages.
One type of prosthesis is made of cobalt-molibdenic plates covered with titanium: it ensures simple and efficient growth of prosthesis to the bone. Between the plates, a nucleus responsible for segment mobility is placed. Such devices are used for disc replacement in the neck-bone. If discs in lumbar vertebra are replaced, prostheses made of cobalt-chrome-molibdenic plates covered with titanium alloy are used. The construction of such implant is similar to the previous one.
However, this is not the only type of implants used today. Surgeons start introducing revolutionary biological prosthesis of intravertebral discs that have features maximally close to natural discs’. Such implants are made of collagen which promotes efficient growth of prosthesis into natural tissues and prevents its wearing.
Besides, modern types of intravertebral discs prostheses can be divided into three main categories:
- spherical implants – their construction reminds of a sphere placed in the hollow part of nucleus pulposus;
- mechanical implants – such prostheses consist of plates with a nucleus in the center and allow fully restoring functions of the spinal cord;
- physiological prostheses – their nucleus is made of polyurethane or hydrogel, and it restores the disc while absorbing and emitting fluid from intervertebral cavity which helps to distribute load optimally.
When this or that type of intervertebral implant is chosen, a doctor should take many factors into consideration, including the peculiarities of condition and its stage, patient’s age, physiological features, etc. For example, when intervertebral discs are replaced in men with a strong muscle frame, prostheses that save joint movement should not be used. In this case, the choice of prosthesis should be individual.
Minimally invasive operations for disc replacement on the spinal cord are performed in two stages:
- removal of the damaged disc;
- installation of prosthesis.
Before the operation, a patient goes through analyses and diagnostics with ultrasound and MRT imaging. The obtained data will help doctor to decide whether full or partial replacement of intravertebral disc is required, and find a suitable prosthesis.
It should be noted that prosthetics of intravertebral disc is a serious surgical invasion, because it affects nervous spinal cord. However, modern German medicine has rich experience of minimally invasive operations on the spinal cord, which allows reducing the risk of damage to minimum. The operation is performed under general anesthesia and lasts for about two hours.
During the procedure, a doctor makes a small cut (not more than 6 cm) and fully removes the intravertebral disc. If the operation is made in the cervical part of the spinal cord, the cut is made on the neck from the left side. If it’s made in the lumbar spine – the cut is made on the abdomen, between the hipbone and the navel. Such access to the spinal cord reduces the risk of damage of spinal nerves.
After that, a special construction that holds the lower part of foramen intervertebrale is installed, after which the surgeon removes vertebral osteophyte, small hernias that push on the spinal cord and nerve roots. At the final stage of the operation, optimal height of the intravertebral disc is adjusted, then the construction is removed for a prosthesis to be installed on its place. This manipulation is made with the help of a microscope only and with X-ray imaging.
Rehabilitation after operation of intravertebral disc prosthetics is very important. After two hours of surgical invasion, a patient is allowed (and even recommended) to move freely, even if he experiences minor post-surgery pain.
Drugs for thrombosis treatment are prescribed before the surgery and when the patient goes home. Several days after the operation, ultrasound imaging is performed to make sure that the blood flow in legs and pelvic zone is normal. If there are no complications, a patient can leave the hospital in 3-4 days.
During 1.5 months after the operation, a patient should wear a special soft bandage (all the time except for when sleeping). During this period, a patient is forbidden to drive a car, motorcycle or any other vehicle.
The control of intervertebral disc prosthesis taking and fixation is made after some certain period with the help of X-ray imaging. When rehabilitation period is over, all restrictions of movement are cancelled, and a patient can get back to usual lifestyle and routine tasks, including sports, exercises, driving of vehicles, physical work, etc.