Multi Axial Screws Help Make Instrumentation Surgery Easier

Peer Reviewed


Surgery  ORThe use of instrumentation - specially designed hooks, rods, and screws - has revolutionized spinal surgery in the last 25 years. As these instrumentation systems continue to develop and progress, millions of patients with a wide variety of serious spinal conditions are finding the help and relief they have been searching for.

If you are in need of spinal surgery that involves the use of instrumentation, surgeons now have a tool that can help make this type of surgery even easier. Medtronic Sofamor Danek's CD HORIZON® M8 Multi Axial Screws are the latest addition to a whole system of instruments designed to stabilize areas of the spine. These specially designed screws facilitate lining up the rods with the pedicle screws. Easier placement means less time spent in surgery for the patient, more successful outcomes, and less recovery time.

When Is Instrumentation Used?

Even though most spinal conditions can be treated using non-surgical methods, if the spine becomes too unstable, pain is unresolvable, or the patient experiences neurological dysfunction, surgery may be the best answer.

Instrumentation systems such as hooks, rods, and screws are used to surgically stabilize spinal trauma and deformity. Often, these implants are used together during a procedure - for example, multiaxial screws help with lining up many of the pedicle screws with the rods. Multiaxial screws cut down, to some extent, on the need for rod contouring, they make it easier to engage rods into pedicle screws and they, as stated, cut down on the stress on the bone-screw interface.

There are a variety of spinal conditions that can cause serious spinal instability. These include:

(1) Degenerative spondylolisthesis - a spinal a disorder that causes the forward motion, or slip, of one vertebral body over the one below.

(2) Spinal fracture - breaks in the bones of the spine, such as the vertebrae.

(3) Scoliosis - curvature of the spine.

(4) Kyphosis - a progressive spinal disorder also called humpback or hunchback.

(5) Spinal tumor - cancerous growths on the spine.

If these spinal conditions progress to a point that the spine becomes seriously unstable, instrumentation surgery is performed to add strength and stability, return functionality, and decrease pain.

Screws and Rods - Adding Strength to the Spine

The pedicle is part of the vertebral column that connects the front of the spine to the back of the spine. There is one pedicle on each side of each vertebra. Placing a screw into the pedicle bone of the vertebral body is done to fixate and stabilized the spine. If necessary, pedicle screws can be placed at several levels of the spine; a rod is then used to connect them together, giving the spine considerable extra strength.

How Do These Screws Work?

Many spinal surgeons use the CD HORIZON® M8 Multi Axial Screws (pictured below) because they can be angled 28° in any direction, making it easier for the surgeon to implant hooks, rods or other instrumentation. They also have break-off heads, a feature that helps the surgeon determine when the screws have been successfully secured. Available in medical grade steel and titanium, these "low-profile" screws are designed to fit most body sizes with minimal interference with other parts of the anatomy. In addition, the M8 Multi Axial Screws include a buttress thread design, a single locking mechanism (break off set screws), and top loading mechanism to facilitate rod placement and reduction.

multiaxial screw

Knowledge is a Powerful Healer

If you are in need of spinal surgery, your surgeon will discuss with you in detail how the procedure will be done. He or she will determine which instrumentation system is best for your particular condition. While it is not necessary to understand all of the technical aspects of how these instrumentation systems are designed and used, many patients find it helpful and comforting to learn a little about the system used in their procedure. Understanding as much as you can about your condition and your surgery can help you as you proceed down the road to recovery.

Updated on: 08/17/15
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The most desirable features of these screws are two-fold. First, in deformities that are complex and stiff, it may be difficult to line up many pedicle screws if the pedicle screws are all fixed angle. A clear example of this is adult scoliosis. The multiaxial design makes it easier to line up the pedicle screws with the rod and, therein, reduces the stress on the screw-bone interface.

The other nice feature is that it is a top-tightening screw. Therein, if revision is needed at a later date, it is much easier to access the implants and remove them than has been the case with other types of fixation between the screws and the rods, which has required either more exposure or is much harder to disassemble. I don't wish to sponsor or promote any particular implant or manufacturer.

Other implant manufacturers have similar designed screws. They are all good and useful products. My greatest experience with the multiaxial design has been with the Medtronic Sofamor Danek product.

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