Spondylolysis relates to instability of specific bones in the low back. It a very common cause of back pain, particularly in adolescents. Gymnasts who perform routines that bend and arch the back are often victims of spondylolysis or spondylolisthesis.
Spondylolisthesis and spondylolysis are caused by joint instability in the low back. The rear part of spinal vertebrae has facet joints that act as hinges, allowing our spines to twist and bend. Sometimes, however, the posterior element can crack. Either from heredity or wear and tear, part of the posterior element called the pars interarticularis can crack, causing the vertebrae slip forward out of its correct position. Spondylolysis occurs when the PARS hinge is cracked, but the vertebrae is still in its correct position. Spondylolisthesis occurs when the cracked PARS has allowed the vertebrae to slide forward out of its correct position. If left untreated, spondylolysis can lead to spondylolisthesis.
Interestingly, in many cases, spondylolisthesis may have no symptoms, so most people may not know they have it. Back pain is the most common symptom, particularly in the lower back. This back pain may be mistaken for a muscle strain. Muscle spasms that occur as a result of spondylolysis may cause an overall feeling of stiffness in the back and may effect posture.
Outlined below are some of the diagnostic tools that your physician may use to gain insight into your condition and determine the best treatment plan for your condition.
X-rays are usually the first step in diagnostic testing methods. X-rays show bones and the space between bones. They are of limited value, however, since they do not show muscles and ligaments.
Conservative treatments should always be considered first when treating spondylolysis. Nonsurgical treatment methods include resting and refraining from usual activities, taking anti-inflammatory medication, and incorporating a stretching and strengthening program. While ligaments and muscles can help hold the vertebrae in place, over time, surgery may be necessary to install surgical instrumentation or bone grafts that lock the vertebra in place so that it does not slide out of position and damage the spinal nerves. Surgery may involve a fusion and/or screws and rods.
Good spinal care, both in developing good musculature and in preventing overuse or injuries, is key into reducing the chance of developing spondylolisthesis. Athletes, especially, need to be knowledgeable about body mechanics and the importance of both strengthening and resting the muscles of the back.
The goals of surgery are to remove pressure on spinal nerves (decompression), and to provide stability to the lumbar spine. Decompression involves removing the damaged structures that are causing the spondylolisthesis. In most cases of spondylolisthesis, lumbar decompression is accompanied by the uniting of one spinal vertebra to the next (spinal fusion) with spinal instrumentation (implants that are used to assist the healing process). Surgery can be performed from the back of the spine (posterior) or from the front of the spine (anterior). A structural graft is inserted into the place previously occupied by the removed structure. The purpose of this graft is to hold the disc space open until the fusion is complete. The graft is often held in place by a "cage" device, such as the BAK cage.
In the laminectomy procedure, the spine is approached through a two-inch to five-inch incision in the midline of the back, and the left and right back muscles are detached from the lamina on both sides. The lamina are flat bone projections on each side of the vertebra. After this is accomplished, the lamina is removed (laminectomy), allowing the doctor to see the nerve roots. The facet joints, which are directly over the nerve roots, may then be trimmed to give the nerve roots more room. Once the nerve roots have adequate space made by the removed lamina and facet joint trimmings, pressure is eliminated, thereby alleviating pain. Bone graft chips may be placed between the vertebrae to create a solid section of bone, preventing motion that may detract from healing.
The posterolateral fusion involves placing bone graft in the posterolateral portion of the spine (behind and to one side of the spine).The surgical approach to the spine is from the back through a midline incision that is approximately three inches to six inches long. First, bone graft is obtained from the pelvis (the iliac crest). Most surgeons work through the same incision to obtain the bone graft and perform the spinal fusion.
Next, the harvested bone graft applied to the posterolateral portion of the spine. This region lies on the outside of the spine and is rich in blood to supply the nutrients for it to grow. A small extension of the vertebral body in this area (transverse process) is a bone that serves as a muscle attachment site. The large back muscles that attach to the transverse processes are elevated to create a bed to lay the bone graft on. The back muscles are then laid back over the bone graft, creating tension to hold the bone graft in place.
After surgery, the body uses a natural process to repair itself, which usually means growing bone. As the harvested bone graft grows and adheres to the transverse processes, the spinal fusion is achieved and motion at that segment is stopped. Spine surgery instrumentation (medical devices) is sometimes used as an adjunct to obtain a solid fusion.
For spine operations to be successful, solid healing of bone across the spine must be achieved. Dr. Regan's private practice makes use of metal devices, also called instrumentation (screws, rods, plates, cables, wires) that can help correct a deformed spine and will also increase the probability of obtaining a solid spinal fusion.
Spinal instrumentation can be placed in the front or in the back portion of the spine. The devices are usually made of metal, commonly stainless steel or titanium. In order to place this instrumentation into the spine, the spine is at first exposed by making a skin incision, and then gently clearing the muscles, ligaments and other soft tissues from the levels of the vertebrae to be fused. Specific tools are used to carefully prepare the bone in such a way to obtain good seating of the implants (screw, rod, wire, cable or other). When these devices are in the proper position, a rod (or plate) is positioned to link the implants together. Screws are inserted into the pedicles, which are part of the arch of the vertebra. This essentially forms a rigid scaffolding to hold the spine in the desired position. The bone graft which has been placed into the area of fusion gradually solidifies over several months. The spinal instrumentation is gradually covered by scar tissue and sometimes bone which the body lays down.
Those with a family history of spondylolysis or weak vertebrae are more susceptible to developing the condition. Also, athletes involved in activities that place a great deal of stress on the back, such as football players and weight lifters, are at greater risk for fracturing the vertebrae, encouraging slippage.
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