Artificial Disc Replacement

Total disc replacement is one of the newest technologies developed to treat discogenic back pain. As well, disc replacement designs have been investigated to treat cervicogenic pain as well as cervical herniated disc disease. The reason these devices have been developed is surgeons wish for an alternative to treat patients with spine problems. The standard of care is to treat the patient with a fusion which is growing two bones together. However a number of studies have shown that patients will develop arthritis above or below a fusion. This happens in as many as 40% of patients over five to 10 years. As well, there is a significant risk of a re-operation due to this arthritis above or below a fusion. Orthopaedic surgeons rarely fuse the hip or knee for arthritis and presently knee and hip replacement is the standard of care. There are some surgeons who feel that total disc replacement might offer a viable option for patients with discogenic back pain. The potential advantages of this procedure are faster return to work and a potential decreased risk of adjacent segment disease. The only product approved, at the writing of this document, for use in the United States is the Charité artificial disc which was developed by surgeons in Germany in the ‘80s. This device has been implanted in Europe for a number of years with good reported success. The remainder of this document will discuss the indications for surgery as well as potential complications which might occur with surgery.

The indications for total disc replacement includes patients with disabling back pain which has persisted for a minimum of six months during an active treatment protocol. Not only must the patient have had the pain for six months, but they must have undergone treatment protocols which include therapy, bracing and/or medications. Chronic back pain is the primary indication for this surgery.


CONTRAINDICATIONS TO DISC REPLACEMENT INCLUDE:

Patients with poor bone quality, osteoporosis or osteopenia and/or other metabolic bone diseases

Patients who have used chronic steroids

Instability of the spine

Patients with severe disease of the facet joints or facet fusions

Either scoliosis or spondylolisthesis

Patients with extruded disc herniations, infections, cancers, metal allergies, autoimmune diseases and pregnancy

Patients with severe stenosis, tumors or scarring around the nerves

In patients who are older than 50 years of age, bone density must be determined using a DEXA scanner. If bone densitometry reveals a loss of bone quality with a T score of -1.0, then disc replacement cannot be performed. In addition, disc replacement is performed from the front of the abdomen so any patients who have severe atherosclerosis (hardening) of the vessels in the abdomen might be contraindicated for this surgery. This is because a significant amount of retraction is required to expose the spine. Patients with severe calcification in their arteries may be at risk for life-threatening blood loss. Patients who are morbidly obese [body mass index (BMI) of greater than 40] a patient who is over 100 pounds over their ideal body weight. In addition patients with severe leg pain due to foraminal stenosis, or due to loss of disc height are contraindicated for this surgery.

Patients who are candidates for disc replacement include skeletally mature patients who have arthritis at the L4-5 disc or L5-S1 disc. Patients who have had a diagnosis of discogenic back pain confirmed with a discogram. Patients who have less than 3mm of spondylolisthesis at the involved levels and who have failed six months of conservative treatment prior to surgery.

Complications which have been reported with disc replacement include a risk of persistent back pain and/or leg pain which can occur to some degree in up to 50% of the patients, nerve injury which can occur in up to 20% of patients, infections which has been reported in as many as 12% of patients, problems with the surgical approach through the abdomen which can occur in up to 10% of patients and the requirement for additional surgery related to the total disc replacement which can occur in up to 5% of patients. Of the patients who developed damaged nerves during the surgery, 10% had symptoms of numbness. However other symptoms include burning pain, weakness, nerve root injury and changes in reflexes.

Complications related to the surgical exposure include damage to the large vessels resulting in major bleeding, retrograde ejaculation/sterility in men, hernias about the incision in the abdomen, requirement for a nasogastric tube to be placed to evacuate the bowels due to an ileus (bowels filling with gas), blood clots which form in the veins, vessel damage, bleeding around the nerves in the epidural space and bleeding which can collect in parts of the abdomen. As well with any surgery in the abdomen, there is risk of scar formation.

Postoperative care after total disc replacement: After a total disc replacement, the patient may or may not wear a lumbar corset for a period of time. This is will be determined by your surgeon after review of the intraoperative events of your surgery. We will ask that you start to walk as soon as possible after surgery and you may be asked to wear thigh high thromboembolic stockings and intermittent compression devices to decrease your risk of deep venous thrombosis (blood clots) initially after surgery. During the first 2-6 weeks after surgery, you will be weaned off of narcotics and nonsteroidal anti-inflammatory medications. We will ask that you avoid hyperextension and extreme flexion exercises. As well, you will begin a physical therapy protocol at approximately 3-4 weeks. Patients will be asked to initiate a flexibility program focusing on flexibility and core strengthening to increase the strength in your abdominal muscles which will help provide improve balance and trunk stabilization. As well, there will be aerobic conditioning involved in this rehabilitation. Within the first month of surgery, you will be involved in stretching, isometric trunk exercises, isometric strengthening and back strengthening. Your follow-up visit will occur at 6-12 weeks after surgery. Radiographs will be taken [flexion, extension and lateral bending] during your follow-up visits. Between 3 and 6 months after your surgery, you will be allowed to increase your activity to include rotation, side bending and more aggressive abdominal strengthening exercises. Most patients will be able to return to sedentary work in approximately 4 weeks. However, patients who have medium to heavy work activities might not return to work for six months.

If you have any additional questions regarding total disc replacement, please contact my nurse, Lori Burke. We will assist you in making a preoperative decision regarding this new and experimental procedure.