Minimally Invasive Lumbar Fusion
First, a spinal fusion is an operation where the soft tissue and disc material between two or more spinal vertebrae are removed and bone graft placed in between, to allow the body to heal these two bones together as one. The biology of the situation is similar to that which occurs in fracture healing. By getting the two spinal bones to fuse together, the pain of the unstable or dysfunctional disc can often be improved.
Page 1: Accessing the Spine
Minimally invasive techniques for accessing the spine can allow the surgeon to get to the essential areas for the surgery with less disruption of the surrounding tissues.
Minimally Invasive Technique
An open approach is pictured here on the right for comparison. While open surgery looks severe, this approach is very common. At the end of the surgery, the wound is sutured closed, however, the muscles are stretched open by the retractors, often for several hours, during the case. There are many situations where an open approach is required.
With a minimally invasive approach using the tubular retractor system, there is less pressure on the surrounding muscles. The back muscles wind up less bruised. The wound is smaller and therefore has less surface area exposed to the environment of the operating room. Less muscle is dissected off the bone, thus preserving the blood supply to the spinal bones. Due to these factors, there may be at least a theoretical decreased risk of infection with minimally invasive cases. Click here for more info on minimally invasive approach.
Here is an example case of a patient who needed a two level fusion. The normal discs are indicated with the black arrows, and the white arrows are pointing to the damaged discs. Note they lack the white center of the other discs. In this MRI imaging sequence, water shows up white, and in the damaged discs, the center (jelly in the donut) is dried out, which is one of the signs of damage.
This patient, who had primarily unremitting low back pain, also failed to improve with non-operative treatment.
In the operating room with the patient under anesthesia, we can feel the bony prominences of the spine in the midline on the back. We measure a certain distance away from the midline, and mark our entry point with a needle.
Using X-ray in the operating room (fluoroscopy), we can see where the needle is to confirm we have the right level.
Here with fluoroscopy, the level is confirmed.
A small skin incision is made.
A guidewire is placed where the needle was, and then tubes are placed over that wire to dilate the opening. Shown here is the first tube that goes over the guidewire.
Larger tubes are placed.
As the larger tubes are placed, the muscles are pushed aside and spread instead of being cauterized off the bone as with the open technique.
Working portal is placed. The opening here is about the size of a quarter.
Lateral (view from the side) X-ray is taken to verify that we are still directed to the right level.
The surgery is done with access through this tube, held in place with a special retractor.
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Decompression and Fusion
Click here to move to Page 3:
Pedicle Screw Fixation