As mentioned elsewhere on this site, the 2 main goals of most spine operations are to decompress pinched nerves and to fuse unstable spinal segments. The second goal (fusing unstable segments) is the topic of this discussion.
Spinal instrumentation has dramatically changed spine surgery over the last 2-3 decades. Historically, the first spinal instrumentation was used in the 1960’s, called the “Harrington rod” for scoliosis. Many advances have been made since then, and today, a wide variety of instrumentation options are available for surgeons to achieve the goal of providing stability to the spine.
The key point to remember is that the purpose of spinal instrumentation is to provide stability to the spine while the fusion is healing.
A key advantage of spine instrumentation is that it provides immediate stability to the spine, such that patients can be mobilized out of bed the day of surgery. In the past, prior to widespread use of instrumentation, patients were kept on bedrest for extended periods of time to allow the fusion to heal prior to mobilizing the patient. Also, braces and casts were used for weeks and months to provide some stability to the spine. These methods are no longer necessary, because the screws and rods that are inserted provide immediate stability to the spine so patients can be mobile while the fusion is healing.
The fusion part of the surgery involves placing bone graft between vertebrae. Once the fusion heals, the spinal instrumentation is no longer serving any function. However, the implants are not removed because they rarely cause symptoms and removing them requires another surgery which is not necessary in most cases.
Screws And Rods
Pedicle screws (pedicle is the portion of the vertebra that connects the front part of the vertebra with the back part) have become the most widely used fixation method in modern spine surgery. They have been used in all areas of spine surgery, including trauma, degenerative conditions, deformity correction and tumors, and in all regions including cervical, thoracic and lumbar spine and the sacrum.
Screws and rods can be made of different materials. Options include titanium, stainless steel and cobalt chrome. Most implants used today are made of titanium.