Water Knife Surgery

May 7, 2006 Back pain is a common complaint. The American Academy of Orthopaedic Surgeons estimates 8 out of every 10 Americans will experience back pain at some point in their lives. The incidence of back pain increases with age. Back pain is more common among those who are obese or less fit, have a family history of back pain, smokers, people who work in jobs that require heavy lifting and patients with arthritis or certain types of cancer (pain occurs when the diseases spread to the spine). Herniated Discs One cause of back pain is a herniated disc. Spinal discs are rubbery pads of tissue located between each of the vertebrae in the spinal column. The discs are like jelly-filled donuts. The outside covering (called the annulus) is made of a tough layer of tissue. Inside, there is a gel-like substance, called the nucleus. Normally, the spinal disc protects the spine and acts like a shock absorber. But sometimes the discs outer layer wears thin and/or the disc loses some of its water content. The disc becomes less flexible. And as it shrinks, the space between the vertebrae narrows. The affected disc can rupture (called a herniated disc), causing some of the inner gel to push out toward the spinal canal and the delicate spinal nerves. A herniated disc can also occur when the outer covering tears from an injury. A herniated disc can occur at any point in the spine. However, most of the time, the problem affects the lower back - in the area around the waist. Patients may experience pain, numbness or tingling that shoots down the back of one leg, or on one side of the buttocks. These symptoms are known as sciatica. According to the North American Spine Society, about 1 to 2 percent of Americans have sciatica. The condition is most common in those 30 to 50. Treating a Herniated Disc Conservative treatment is effective in relieving pain for 80 to 90 percent of patients with a herniated disc. Initially, doctors may recommend limited bed rest and over-the-counter pain relievers. Prescription medications may be needed by some patients. Physical therapy and prescribed exercises are important to strengthen the back muscles and improve flexibility and endurance. When conservative measures dont provide adequate relief, doctors may recommend surgery. There are several surgical options for a herniated disc. In a traditional discectomy, an incision is made into the back to access the spine. A small portion of the bone behind the disc may need to be removed. The herniated disc is then removed. Removal of the disc means the spine needs to be stabilized to prevent the vertebrae from compressing. A small piece of bone may be placed into the space. As the area heals, the bone grows into the spine, fusing the upper and lower vertebrae into a single segment of bone. Tiny metal rods, plates and screws may be implanted at the time of surgery to help stabilize the spine. A less invasive approach is called a microdiscectomy. The procedure is similar to a discectomy. But doctors make only a very small incision into the back and uses tiny instruments to perform the surgery. Using a Water Knife for Herniated Disc Some surgeons are using another technique for microdiscectomy, called a water knife. Instead of using a scalpel or laser to cut and remove tissue, the SpineJet® HydroDiscectomy™ System (HydroCision®) uses a high-powered stream of water. First, the patient is given a local anesthetic. Then, a fluoroscope (special type of live X-ray machine) is used to produce images of the spine, allowing doctors to precisely locate the area of treatment. Next, a tiny cut is made into the skin. A thin needle is inserted through the cut and guided (using the X-rays for visualization) into the disc. Then, a slightly larger hollow needle (called a dilator) is inserted over the guide needle into the space. The dilator gently separates the tissues and eliminates the need for a larger incision. Then, surgeons slide a cannula over the dilator. The dilator and guide needle are removed, leaving only the cannula in position. Next, the SpineJet device is inserted inside the cannula. The SpineJet delivers a high-velocity stream of water that cuts and removes a small amount of the material inside the disc (about 2 to 3 cc). At the same time, the water and tissue are suctioned back into the cannula. Removing some of the gel-like contents inside the disc shrinks the size of the disc slightly and reduces the pressure caused by the herniation. The procedure takes about 30 to 45 minutes. Water knife surgery uses such a small incision (less than half an inch) no stitches are needed to close the opening. Patients generally only require a bandage to cover the opening. Most are able to go home the same day and return to work in 2 to 3 days. Physical therapy and stretching exercises are started in about one week. Compared to traditional surgery, patients having HydroDiscectomy have less pain and a faster recovery. There is also less risk of infection and scarring. Doctors can use the water knife to treat up to three discs at one time. The procedure may be useful for patients who dont get adequate relief from other non-surgical treatments and need surgery. The treatment is not recommended for patients with spinal stenosis (narrowing of the spinal canal), those in whom discs have ruptured into the spinal canal or patients who are having bowel or bladder problems from the disc herniation. The water knife technology is also useful for a number of other surgical procedures, like debridement of burn wounds, removal of cysts in the liver, and gallbladder removal. AUDIENCE INQUIRY For information on the SpineJet® HydroDiscectomy™ System, http://www.hydrocision.com For information on back or disc pain: American Academy of Orthopaedic Surgeons, http://orthoinfo.aaos.org National Institute of Arthritis and Musculoskeletal and Skin Diseases, http://www.niams.nih.gov North American Spine Society, http://www.spine.org BIBLIOGRAPHY "Discectomy," LaGrange: North American Spine Society, downloaded from website (http://www.spine.org), March 24, 2006. German, John, M.D., and Kevin Foley, M.D., "Minimal Access Surgical Techniques in the Management of the Painful Lumbar Motion Segment," Spine, August 15, 2005, Vol. 30, No. 16, Suppl., pp. S52-S59. 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"The Spine," Rosemont: American Academy of Orthopaedic Surgeons, downloaded from website (http://orthoinfo.aaos.org), March 24, 2006. Wang, Jeremy, M.D., et al., "Current Treatment Strategies for the Painful Lumbar Motion Segment," Spine, August 15, 2005, Vol. 30, No. 16, Suppl., pp. S33-S43. Research compiled and edited by Barbara