Medtronic Sofamor Danek, the global leader in spinal instrumentation, has recently developed the CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System. This System allows spine surgeons to stabilize the posterior aspect of the spine with smaller incisions and less damage to the ligaments, fascia, and muscles of the spine than with a traditional "open" posterior spinal fusion. The CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System is the most recent addition to the Minimal Access Spinal Technologies (M.A.S.T.) family, joining the METRxTM System and the CD HORIZON® ECLIPSE™ Spinal System. With the development of each system, Medtronic Sofamor Danek has solidified its ongoing commitment to advancing minimally invasive spine surgery.

Percutaneous Pedicle Screws in Minimally Invasive Spine Surgery
The CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System was designed in order to allow surgeons to connect percutaneously inserted pedicle screws along the posterior aspect of the spine with a rigid rod in order to stabilize the intervening motion segments. This accomplishes the same goals as placing pedicle screw-based spinal instrumentation in the posterior aspect of the spine via a conventional "open" exposure. However, this System has been designed to permit this type of instrumentation without an extensive surgical exposure, which minimizes the amount of damage done to the muscles, ligaments, and fascia of the back. This may offer significant advantages in terms of improved pain relief after spine surgery and decreased scar tissue formation in the spina erecta muscles. Recovery after major spinal surgery can be very difficult, and several studies have shown that an extensive surgical exposure and prolonged periods of retraction can seriously injure the major muscles of the back. This may have long-term consequences in terms of full recovery after spine surgery and regaining the muscle endurance that is a natural part of a healthy back.

The CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System uses very small incisions, which limits the amount of trauma to the surrounding tissues, but this technique also limits what type of surgery can be performed on the spine. With a percutaneous pedicle screw technique, direct decompression of the neural elements cannot be accomplished. Some decompression of the neural elements is possible by distracting one vertebral body with respect to the other body with this system. However, the surgeon is not able to physically feel how much space is available for the spinal cord and exiting nerve roots. Therefore, a fusion must be the primary goal of a surgical procedure using the CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System, and direct decompression of the neural elements via a posterior approach must be unnecessary. There are several spinal disorders that may be amenable to this type of treatment, including certain types of spondylolisthesis, pseudoarthrosis after an anterior interbody fusion or an un-instrumented posterior spinal fusion, and also when certain types of posterior spinal instrumentation is used to augment an anterior interbody fusion.

Frequently Asked Questions
Q: What is the benefit of percutaneous pedicle screws?
A: The benefit is that there is much less trauma to the soft tissue surrounding the spine. Less trauma to the musculature means less post-op pain and a quicker recovery time. Minimally invasive fusion techniques are continuing to develop making the traditional, highly invasive posterior fusion unnecessary in many cases.

Q: How successful has this system been?
A: During the first year (2000), almost 100 cases were done. Cases are being performed at an increasing rate because of the early success. Many surgeons say their patients are much more satisfied with the minimally invasive surgery vs. the traditional methods. Blood loss, morbidity and hospital stays were decreased significantly in these patients.

Q: How is this different that traditional fixation techniques?
A: The implants are identical to screws used for open procedures. The rod insertion instrumentation is the only difference. Since the hardware is the same, there is very little difference in the fixation achieved from an open procedure. The big difference is post-op morbidity at the posterior surgical site.

Q: But don't a lot of little incisions add up to one long incision?
A: It seems as though skin incisions hurt less than the muscle stripping that is necessary for open posterior fixation. The CD HORIZON® SEXTANT™ Percutaneous Rod Insertion System utilizes muscle dilation approaches similar to the METRx™ System that do very little damage to the soft tissue below the skin. Muscle is left undisturbed at the level of the spine and is thought to account for the reduction in pain.