Minimally invasive spine surgery was born from the idea that surgeons should be able to do more with less harm. Early surgeons were limited in their explorations of the human body by the lack of safe anesthesia, excessive blood loss, and infection. Gradual growth in the fields of Anesthesiology, Hematology and Microbiology led to a golden age of surgery, where surgeons could and would often boldly go where no one had dared to go before.
During the 1800s a simple telescope was invented to examine the inside of the urinary system. Further developments occurred over the following 150 years the the late 1900s where the invention of a rod-lens system (a telescope with solid lenses within the tube rather than an objective and an eyepiece) and a cold light (halogen source) and fibre optics transformed abdominal surgery to a point where laparoscopy is both standard of care and certain surgeries which were near impossible open were now both safe and feasible with the laparoscopes. The results speak for themselves. Faster recovery, reduced post operative pain and earlier return to normal life has become the norm rather than the exception.
Spine surgery was a little behind abdominal, urological and ENT surgery in the adoption of minimally invasive techniques for one major reason – the long tubular cameras needed an empty space to move around in. The muscles around the spine did not provide the required maneuverability. Ironically, it was to avoid damage to these muscles that Minimally Invasive Spine Surgery grew as a technique.
The muscles around the spine provide a dynamic support to the bony and ligamentous spinal column. The muscles cause the forward, backward, sideward and twisting movements that make our spine supple and at the same time strong enough to bear our own weight. These muscles act like the bow string of a bow when stabilizing the spine. And just like a loose bowstring makes a bow useless, the paraspinals need to be strong for a good spine support.
The paraspinals are a group of muscles that act as single functional unit all the way from the base of the skull to the sacrum. They attach closely to the vertebrae that form the spine and it is this attachment that is traditionally dissected free when doing open spine surgery.
The muscles then heal over time but MRI studies long after spine surgery show changes in these muscles which indicate that they may never really regain their original strength. Minimally invasive surgery of the spine makes dissecting these muscles off the spine unnecessary. The approach corridors are different and involve only stretching muscle rather than dissecting or cutting.
This is done either with an endoscope or by a variety of tubular retractors that allow surgeons to operate via a tunnel that keeps the muscles temporary separated. At the end of the surgery the retractor is removed and the muscles fall back to their original position. While this technique has a learning curve, in experiences hands it is safe and even quicker than traditional surgery, and has fewer risks of infection.
For example surgery for removal of a prolapsed or extruded lumbar disc is done usually via an 18-22mm incision. And usually takes under an hour. The wound is closed with absorbable sutures and the patients can walk home even the same day. The marked reduction in postoperative pain and remarkable recovery make this an excellent technique.
Even for more complex spine surgeries like placement of screws into multiple levels of the spine, minimal access approaches have both reduced blood loss and need for prolonged postoperative rest. This allows surgeons to get their patients on their feet much sooner than before and that is and has always been the primary goal of the surgery.