This surgery is performed when treating chronic lower back pain resulting from disc degeneration.
The intervertebral disc is a soft tissue that lays between two vertebrae (spinal bones). The intervertebral disc is made up of a soft jelly-like substance (nucleus pulposus) surrounded by layers of collagen tissue (annulus fibrosis). In a healthy disc, the nucleus pulposus is well hydrated and it works as a shock absorber. At times, the nucleus pulposus can deteriorate due to many causes (some of which are not well understood). It loses the ability to hold water and becomes stiff. The loss of the shock absorber action (like a flat tyre) places an irregular strain on the surrounding annulus fibrosis leading to damage. As a result, disc degeneration causes low back pain.
Role of lumbar disc replacement
The goal of the surgery is to remove the degenerated and painful disc, which then will reduce the back pain, and will restore the movement of the spine using an artificial disc. The three-piece prosthesis involves two cobalt-chromium-molybdenum plates spray-coated with titanium that are attached to the vertebrae by a keel. A polyethylene (plastic) core is placed between the two metal plates and allows for spinal mobility.
About the surgery
Anaesthesia: The surgery is done under general anesthesia. During the procedure, the patient will be lying on his/her back.
Procedure: A 7-10cm incision is made in the abdomen and the abdominal muscles (rectus abdominis) are retracted to the side. The abdominal contents (intestines) that lie inside a large sack (peritoneum) are moved aside to allow access to the front of the spine. The large blood vessels that continue to the legs (aorta and vena cava) lie in front of the spine and are also moved gently aside. After the blood vessels have been moved aside, the intervertebral disc is excised and the resultant space fitted with the artificial disc. The two metal plates of the artificial disc are inserted, followed by the polyethylene (plastic) core. The incision is closed with dissolvable sutures and a drain tube removes the blood that collects at the surgical site.
In the recovery room: After the surgery, you may feel some pain on the operated area when you wake up. Pain medications, antibiotics, and IV fluids will help you stay hydrated and stable. You may also receive a temporary urinary catheter to use the bathroom.
In the ward: After your surgery, you’ll be put on a liquid diet before slowly going back to a full, regular diet. You may only drink sips of fluids immediately after the surgery. You will be provided with medications to relieve your pain for 1-2 weeks. However, please remember to notify a nurse if you feel extreme pain! Additionally, the drain tube and catheter will be removed a day after the surgery. You will then be able to walk around with a support brace. Typically, you’ll stay in the hospital for 3-5 days, depending on your surgeon’s suggestions.
At home: Remember to stay active to speed up your recovery! Take short walks every day and slowly increase the distance. Please avoid heavy lifting, strenuous activity, and excessive movement of your neck. If you can, try to have someone to help you with your chores and errands for the first few weeks. The last thing you want to do is over-exert yourself!
Risks and potential complications
Keep in mind all surgical procedures come with a risk of complications. You should thoroughly talk about these risks with your surgeon before the procedure. Remember to list out any allergic reactions to anesthesia or other medicines to your surgeon and anaesthetist. Other chronic illnesses related to your heart or lungs – such as hypertension, diabetes and asthma – should also be disclosed. Provide a list of all your current and past medications. Remember, unexpected complications such as stroke, heart attack, and pneumonia are not caused by surgical treatment and are generally rare. However, these rare complications may have serious consequences.
Surgical complications can include bleeding, infection, spinal fluid leak, injury to the veins and arteries near the spine, or injury to the nerve tissue or the protective layer surrounding it. Injury to the nerves may occur during surgery, resulting in paralysis of certain muscles in the legs and loss of sensations. Loss of bowel and bladder control can also occur due to nerve injury. An injury to the dura, the outermost layers of the nerves, can result in leakage of spinal fluid and may occasionally require a repeat surgery to control the leak. The insertion of the screws can potentially cause nerve injury resulting in weakness and abnormal sensations in the legs. Great care is taken to ensure the accurate placement of the screws, which includes the use of intraoperative fluoroscopy (x-rays).
Although antibiotics are given before and after surgery, there is a 1-5% chance of wound infection. Superficial mild infections can be treated with antibiotics, while deep infections may require a wound wash-out under anaesthesia. If you have had an infection in any other area (urinary bladder, chest and skin) immediately before surgery, you may be at a higher risk of post-operative infection in the spine, so make sure to let your surgeon know.
Deep vein thrombosis (DVT – clotting of blood in your calf muscles) and pulmonary embolism (clot migrating to your lungs) are not common after an elective spine surgery, especially when you are out of bed and walking within 24 hours after surgery. We do not routinely use medications to prevent DVT; however, if you have had an episode of DVT in the past, let your surgeon know.
A major risk that is unique to the anterior disc surgery is damage to the large blood vessels that lie close to the spine and can possibly lead to excessive blood loss. Medical studies put this risk at 1% -2%.
For males, there is an unique risk that may occur while approaching the L5-S1 disc. Directly over the disc interspace, there are small nerves that control a valve that causes the ejaculate to be pushed outward during intercourse. By dissecting over the disc space the nerves can stop working, and without this coordinating innervation to the valve, the ejaculate takes the path of least resistance, which is up into the bladder – a condition known as retrograde ejaculation. The sensation of ejaculating is largely the same, but it makes conception very difficult (special harvesting techniques can be utilized). Fortunately, retrograde ejaculation is uncommon and it happens in less than 1% of cases and usually will resolve over time (a few months to a year). This complication does not result in impotence as these nerves do not control erection.
Notify your surgeon at once if you notice the following after surgery
- Extreme bleeding
- Redness or discharge from the wound
- Continuous headache
- Weakness or numbness in the arms and legs
- Difficulty urinating
Talk to your surgeon
This is a concise overview and does not include all the known facts about your condition and the surgery. If you have any questions, make sure to seek any clarifications from your surgeon and his team. It is important for you to attain a clear understanding of your condition and the risks, benefits, and limitations of the surgical procedure before taking action.