Minimally Invasive Surgery (MIS) for Spinal Problems

Article written by Mark Wolgin, MD

The term "Minimally Invasive" in most cases, when describing a surgical procedure, refers to a technique using small incisions to gain access to the particular area of the body needing treatment. By avoiding a larger incision, there can be less force from the retractors on the surrounding tissues, less tissue dissection, and usually better preservation of the surrounding blood supply to the tissues in the operated area. Ideally, these factors lead to quicker healing and a recovery with less pain, although these differences have not been proven conclusively. For an "open" procedure (non-MIS), the surgical wound is larger and more dissection is required. Retraction on the muscles, when kept in place during a long procedure, has been shown to cause damage to these muscles, with some of these effects possibly permanent.

The comparison between minimally invasive and open surgery can be made when describing a lumbar fusion. This procedure typically has the patient lying face down during the surgery, with the work done on the back side (posterior). With an open case, the incision is usually in the midline and the muscles are spread to the sides by retractors. Since the natural tendency of the muscles is to return to the midline, the force can be fairly high at the spot where the retractor is in contact with the muscles. If the surgeon tries to minimize the length of the incision with the open technique, he/she may have to use the retractors to spread harder to see the areas where the work needs to be done. These retractor-induced forces can be reduced somewhat by, paradoxically, making a longer incision. With a minimally invasive approach, usually a tubular retractor is used. After the appropriate level of the spine is identified with x-ray, first small, then sequentially larger tubes are placed, one over another, to dilate (expand) the opening. The force on the muscles is distributed more equally in a direction like spokes on a wheel, with less localized pressure and thus less potential for muscle damage.

While many patients will feel an attraction to the advantages of a minimally invasive approach, there still needs to be an understanding of all aspects of the surgical plan in order to make an informed decision. Patients need to know the rationale behind the proposed surgery, the chances of success and expected rehab course, and probably most importantly, the risks.

While minimally invasive spine surgery has many advantages, which are summarized below, anyone considering surgery on their spine should know that there are still potential risks, even with a small incision. An internet search of "minimally invasive spine surgery" will produce links to many websites stocked with shining testimonials of how much better the patients felt after the advertised procedure, but there is often little discussion of long term follow-up, rates of recurrence of symptoms, or risk of having no relief or being worse. Minimally invasive spine surgery is still spine surgery.

To summarize, the advantages and disadvantages of minimally invasive spine surgery are:

Advantages:

  • Smaller incisions, usually a few smaller scars instead of one larger scar
  • Less tissue dissection
  • Less damage to surrounding muscles
  • Potential for less blood loss, quicker healing, shorter hospital stay, and less pain
  • Quicker return to daily activities

Disadvantages:

  • Potential for prolonged operative time
  • Usually associated with increased radiation exposure
  • Not appropriate for every case
  • Less surface area of bone exposed for fusion cases
  • May be difficult to repair a spinal fluid leak if one occurs
  • Learning curve for surgeons (takes a few cases to develop competence)

For patients considering a minimally invasive approach, they should understand that each case is considered individually, and they should consult their doctor to see what might be appropriate treatment options after non-operative treatments have been exhausted.