Minimally invasive posterior lumbar surgery is based on the following key concepts:
A small one-inch incision is made on your back over the operative disc (A&B). A series of dilators (C&D) are placed at the operative level so as to spread the muscle tissue rather than cut it.
Once the largest dilator (E) has been placed, a one-inch-diameter, tube-shaped retractor is inserted over the last dilator.
The tube retractor is attached to a bed-mounted clamp to secure it in place. The surgery is then performed through this tube with the assistance of a microscope (F). A small amount of bone is trimmed from the lamina to create a space between the two vertebrae.
Since only a small amount of bone is removed, no instability results from this. A ligament between the vertebrae is removed in order to gain access to the disc. This ligament can be removed with no deleterious consequences. Utilizing a microscope, the nerve is visualized and then retracted towards the middle of the spine. I then remove any loose fragments or disc material that is pressing on the nerve.
The incision is usually about an inch in length (G).
Patients are positioned face-down on the operating table. The location of the incision is then confirmed by an intraoperative X-ray. A skin incision about One inch in length is made to one side of the middle of the back at the surgical level. Dilators are sequentially placed to split the muscle down to the lamina, the back part of the spine.
A retractor is then placed to hold the muscle tissue back and allow surgical access to the spine. Using a microscope, overlying soft tissue is removed and the bone exposed. Use of a microscope improves surgical lighting and vision, making the surgery more precise and accurate. Specially designed surgical instruments are then used to remove bone spurs and the lamina on the side of the approach. This is referred to as a lumbar laminectomy or lumbar decompression. The table is then tilted and the spinous process undercut. The anterior part of the lamina on the other side may then be removed. The ligament under the bone is opened and removed using special biting instruments. The disc can also be checked.
Both sides may be decompressed from an incision made from only one side. This preserves the midline spinous process and ligaments and reduces the chance of the spine becoming unstable. The contra-lateral facet joint is also preserved. This makes the surgery much less destabilizing than open laminectomy. With open surgery, laminectomy is usually combined with fusion as open laminectomy alone in this condition destabilizes the spine too much. With minimally invasive laminectomy, I have treated many patients with spondylolisthesis and stenosis with decompression alone. Clinical outcomes have generally been excellent. Avoiding fusion in this setting allows a much faster recovery and a reduction in complications. Not all patients are candidates for minimally invasive laminectomy.
Minimally invasive lumbar laminectomy generally involves smaller incisions, less postoperative pain, and less blood loss than open laminectomy. In addition to being less destabilizing to the spine, recovery is often faster. Many patients with spinal stenosis are elderly. However, minimally invasive lumbar laminectomy is more easily tolerated in this setting than open back surgery. I have successfully performed minimally invasive lumbar laminectomy in many patients in their 80’s. These patients have generally had a good outcome from surgery. Thus advanced age alone may not be an absolute contraindication to surgery in this setting.
Patients typically begin walking immediately after lumbar stenosis surgery. Most patients can go home the day after surgery, even if more than one level in the back requires surgery. By two weeks post-op, most patients are reducing their pain medication usage. Many already note an improved ability to walk and are standing up straighter than prior to back surgery. Full effects of surgery take up to 6 months.
In some cases, minimally invasive lumbar laminectomy may not be the best option for surgical treatment. Some patients with scar tissue from previous surgery, spinal deformities, or excess obesity may benefit from traditional open back surgery instead. Not all patients and not all conditions can be treated via a minimally invasive approach.
Fusing the spine is aimed at alleviating pain that is believed to originate from a motion segment(level) in the spine. There is some new evidence about these types of procedures, and the use of a minimally invasive approach may be considered in selected patients.
This type of procedure uses narrow surgical instruments which are inserted through small (1 to 1 ½ inches) incisions to complete the operation.
The goals of minimally invasive spine fusion surgery include:
The theory with any minimally invasive spine surgery procedure is that smaller incisions and percutaneous approach will create less tissue damage, less blood loss, shorter hospital stays and faster recovery. A minimally invasive spine fusion uses instruments which are designed to allow placement of pedicle screws (into the pedicles on each side of the vertebral bone) and rods (which connect the screws) into the spine. These minimally invasive spine surgery approach use several small incisions in the skin, which have the advantage of being able to spare muscle. The surgeon is guided by intraoperative imaging technology that projects the anatomical images onto monitors. The theoretical advantage is that the screws and rods are placed into the bone in the spine with minimal trauma to the muscle and tendons in the back.
Minimally invasive cervical laminaecotmy can be performed for certain cervical disc herniations. Just like with other MIS techniques a series of retractors is docked on the spine (select MIS Microdiscectomy section from dropdown menu). A microscope is brought into the field and all of the work is done through a 1 inch working tube.