A newer alternative to the classic spinal fusion surgery for spinal disc problems, disc replacement surgery, takes some of the technology used for artificial hips and knees and applies it to blown discs in the back. Two spine surgeons from Orthopedic Associates of Dutchess County will be speaking to the public this month on this relatively new technique, which was only approved by the FDA ten years ago.
At some point in our lives about three-quarters of us will have low back pain, according to the American Academy of Orthopedic Surgeons. With artificial disc replacement surgery, a mechanical disc — made all of metal (such as cobalt chromium or titanium alloy) or a combination of metal and plastic (medical grade polyethylene) like with artificial knees and hips — stands in for a degenerated disc. Currently the FDA has approved two models for lumbar (lower back) disc replacement and six for the cervical, or neck region, where there are six discs, but that is a less common site for disc replacement surgery than the lumbar region.
The spinal column is made up of bones stacked vertically — sturdier ones at the bottom to support the weight of the torso (lumbar) and more delicate and flexible bones at the top (cervical) to allow for the many and varied movements of the head. The less flexible vertebrae in the middle, attached to ribs, are called thoracic, and disc problems in the region are more rare, and surgery more complicated because of the proximity to the lungs.
The vertebrae are connected with small facet joints that allow flexibility of the spine, and in between them are 23 soft, spongy, shock-absorbing discs. The sturdy exterior of each disc covers a delicate jelly-like interior supported by an outer collagen core. To do its job that inside stuff — made of fibers suspended in mucoprotein gel — has to maintain its strength and gelatinousness both. But as we get older the discs lose water, strength and flexibility and the inner core can ooze out through the outer core and rub against the spinal nerve root; this is a herniated disc. Injury can cause this as well.
Traditionally, if non-surgical treatments failed to alleviate the back pain from disc issues fusion surgery would be considered, and often still is. As the name implies, bone is fused to halt movements that cause pain at the discs, with bone graft from a synthetic source or the patient’s own, using cages or screws to support the spine as the bone fuses. Sometimes this helps and sometimes not so much, so disc replacement (ADR) has emerged as a potential alternative, although not everyone is eligible.
The patients with the best chance of success with the surgery are those who don’t have excessive weight, problems with the nerves or joints of the spine, structural defects of the spine, or a history of previous spinal surgery. Usually screening tests like X-rays, CAT scans or MRIs are performed to determine if the patient is a good candidate for the surgery.
The surgery takes about two or three hours and is performed through an abdominal incision, with internal organs moved to the side to access the spine. There is no altering of the bone structure that would require bone healing, as with fusion surgery, so after surgery the patient can return to moving the torso, standing and walking relatively quickly. The time needed to recuperate in the hospital before going home is about two to four days. The decrease in pain may be another few weeks or longer however, although walking, stretching and gentle trunk twists may be recommended to expedite that. FDA-supervised trials showed that disc replacement usually helps but doesn’t always completely remove all back discomfort, reports the AAOS.
The surgery is riskier than fusion surgery, according to Johns Hopkins, because it requires greater access to the spine. Complications could include loosening, fracture or dislodgement of the disc, infection at the site or nearby areas, or rigidity or stenosis of the spine.
The Spine Team at Orthopedic Associates of Dutchess County is making efforts to educate the public about this relatively new technology to alleviate pain and suffering in some of their patients. Their surgeons and non-surgical spine specialists are board certified and fellowship-trained and offer many treatments of spinal problems caused by trauma, deformity and degeneration, with both surgical and non-surgical approaches. In many cases when surgery is advised it is minimally invasive procedures like kyphoplasty, which stabilizes fractures, or microdiscectomy, which promotes nerve healing by removing a small portion of the bone over the nerve root and/or disc material from under it.