Minimally invasive spine surgery, or MIS spine surgery, is a set of techniques which allows the surgeon to use smaller incisions, minimize tissue damage and instability, minimize blood loss, reduce pain medication use, while allowing for earlier mobilization and improved outcomes. These techniques have been relatively recently developed, and are continually undergoing refinement in terms of technology of the instrumentation and improvements in technique.
Traditional, or open spine surgery involves exposing all the bone and soft tissues of the area to be operated upon, and beyond. This requires stripping the muscle off its bony attachments to give the surgeon direct vision and a panoramic view of the area of surgery. This allows the surgeons to use anatomic landmarks that he or she can see, in order to perform the procedure.
The disadvantages of creating a large exposure are several and significant:
1. Large amounts of tissue disruption and blood loss, with greater need for blood transfusion.
2. Increased postoperative pain, opiate medication use, and delayed mobilization. Thus, the patient's progression to recovery and activity are delayed.
3. Scarring and injury to the spinal muscles, which lead to stiffness and instability.
Below is an example of an open exposure for a single level posterior fusion:
Minimally invasive spine surgery involves the use of real-time X-ray, called fluoroscopy, and a GPS-type navigation, called stereotaxis, to accomplish the surgical goals. Small incisions are made, and long thin retractors are guided to the target areas. An operative microscope is used when direct vision is necessary, eliminating the need for wide exposure.
Using these techniques, the surgeon can accomplish all the necessary goals of the particular patient's spinal surgery: decompression of nerves to stop and reverse nerve damage, restoration of normal alignement using cages, and stabilization with screws.
The photo below shows a typical lumbar fusion using a minimally invasive retractor through a 1.5 inch incision and an operating microscope to perform a laminectomy and place a titanium cage into the disc space.
Stereotactic guidance is also used to help guide the precise placement of screws:
The benefits of minimally invasive spine surgery have been clearly demonstrated:
1. Less tissue disruption leads to much less blood loss.
2. Lower infection rates.
3. Less use of opiate pain medications.
4. Earlier mobilization and progression to functional activity and exercise.
Minimally invasive spine surgery techniques are not yet widely used. This is partly because these techniques are relatively new compared to traditional open surgery. From the surgeon's perspective, these techniques are very different from traditional techniques, require different skill sets, and have a steep learning curve. Over the past 2 decades or so, enough evidence has emerged to demonstrated their advantages.
X-ray images of an MIS fusion show good placement of hardware and correction of alignment:
The Future of Spine Surgery
I believe that in the intermediate future, nearly all spine surgery will be done minimally invasively. We are currently in a transition phase in which some surgeons are not adopting the techniques, while others are applying them and refining these techniques. The technology for the instrumentation and approaches have improved greatly even in the past several years, and will continue to do so.
Therefore I believe that every patient who is a candidate for spine surgery should consider if minimally invasive options are right for them. This should be part of the discussion which should take place between the patient and the surgeon.
