Long, open incisions to perform surgery on the lumbar spine (low back area) are no longer needed. New surgical tools and techniques make it possible to complete decompression and fusion procedures with several smaller incisions. This new approach is referred to as minimally invasive surgery (MIS).
The main advantage of the minimally invasive approach is less trauma to the bones, muscles, tendons, and other soft tissues of the spine. There is less bleeding and a faster recovery time. But even so, this technique requires the use of retractors to pull the tissues apart in order to give the surgeon access to the spine.
Even with a smaller incision, there is still the risk of trauma (cutting or crushing) to the soft tissues when using a minimally invasive approach. There is a learning curve that may contribute to problems. Studies show that surgeons have much greater success as their level of experience with this procedure increases. Reports of complications and problems are much higher at the beginning when surgeons are just starting to use this method.
In this article, a surgeon from the Spine Institute of San Diego, California reviews and summarizes studies published to date on the minimally invasive surgical technique for lumbar spine surgery. The goal was to report on ways to prevent muscle injury when using the posterior minimally invasive approach.
Even though the minimally invasive approach creates less trauma, injury, and damage to soft tissues when compared with an open incision, there have still been problems with this technique. At first, the procedure was done using an incision along the middle of the spine. But this midline approach cut through an important spinal muscle (the multifidus). Muscle weakness resulted in loss of function of this important spine stabilizer.
As a result, surgeons started making incisions on either side of the spine in order to avoid cutting the attachment of the multifidus muscle to the spinous process. The spinous process is the bump you feel along the spine, often referred to as your “back bone”.
A second change that has come about is the use of tubular retractors used to hold the soft tissues apart after the incision is made. The retractors are attached to the table. There are two advantages to this tool: 1) a surgical assistant no longer has to hold the retractors steady for the entire length of the operation and 2) pressure on the soft tissues, nerve, and blood vessels can be minimized.
These new table-mounted retractors are a great improvement over the self-retaining retractors used before. During long periods of retraction, pressure from the table-mounted retractors can be released from time to time. This feature reduces force and load on the muscles and tendons and helps maintain good blood supply to those areas. With shorter retraction times and periodic release of pressure, there are also fewer nerve injuries contributing to muscle weakness.
In summary, minimally invasive lumbar spine procedures have reduced the effects of muscle cutting and stripping that normally takes place with an open incision approach. But problems can still develop so surgeons have found even better ways to perform the minimally invasive technique.
Change in location of the incisions and safer ways to retract the soft tissues are now advised. Anything that can be done to reduce trauma to the soft tissues will provide a better result with fewer complications and problems. The patient benefits from the minimally invasive procedure without the added loss of spinal stability as an unfortunate side effect of the technique.