The lamina is a piece of bone that forms the roof over the spinal canal. In patients with spinal stenosis, the spinal canal narrows, with resultant pressure on the nerves. A laminectomy can effectively decompress the nerves and resolve the neurologic symptoms. This procedure is designed to remove a small portion of the bone over the nerve root and/or disc material from under the nerve root to give the nerve root more space and a better healing environment. The surgery involves a 1-4 inch incision in the midline of the lower back, depending on the extent of decompression necessary. Most patients note an immediate improvement in the preoperative leg pain. A small laminectomy can be performed as an outpatient procedure, though usually a one or two night hospital stay is necessary, depending on the extent of decompression required.
A lumbar microdiscectomy is designed to remove herniated disc material that is compressing a nerve root, causing pain and/or weakness in the leg. In a lumbar microdiscectomy, a small incision is made in the midline of the lower back. Precision tools are used to remove a small portion of the lamina, or the bony the roof of the spinal canal. The herniated portion of the disc is removed while carefully protecting the nerve roots, under the magnification of a microscope. Most patients note an immediate improvement in the preoperative leg pain. Lumbar microdiscectomies can be performed as an outpatient procedure, with most patients going home a few hours after the surgery.
Anterior lumbar interbody fusion (ALIF)
In the ALIF approach, a three-inch to five-inch incision is made on the left side of the front of the abdomen and the abdominal muscles are retracted to the side to access the front of the spine.
Since the anterior abdominal muscle in the midline (rectus abdominis) runs vertically, it does not need to be cut and easily retracts to the side. The abdominal contents lay inside a large sack (peritoneum) that can also be retracted, thus allowing access to the front of the spine without actually entering the abdomen. A vascular surgeon usually performs the approach to the front of the spine, since large blood vessels, the aorta and vena cava, need to be protected in this approach.
The disc is removed in its entirety, and a cage with bone graft material is placed in the disc space, decompressing the nerves, and providing stability to the spine. The vertebrae fuse together over the ensuing few months.
The ALIF approach is advantageous in that, unlike the posterior approaches, both the back muscles and nerves remain undisturbed. Another advantage is that placing the bone graft in the front of the spine places it in compression, and bone in compression tends to fuse better. Lastly, a much larger implant can be inserted through an anterior approach, and this provides for better initial stability of the fusion construct.
Extreme lateral interbody fusion (XLIF)
XLIF is a minimally-invasive technique to achieve a spinal fusion. In this approach, a small incision is made on the side of the abdomen, and a specialized retractor and nerve monitoring equipment is used to safely access the spinal disc. The disc is removed, and a cage and bone graft material is placed in the disc space, decompressing the nerves and stabilizing the spine. Usually, pedicle screws are then inserted through small minimally-invasive incisions from the back of the spine for added stability. The vertebrae fuse together over the ensuing few months as the healing process progresses.
Minimally invasive surgery is advantageous because it may allow for less tissue trauma, less scarring, shorter hospital stays and less postoperative discomfort, thereby affording a decreased need for post-operative pain medication.
This technique, while very useful, is not applicable in every case where a spinal fusion is required, due to anatomic considerations. When an XLIF approach is not possible or safe, other minimally-invasive approaches could be utilized to achieve the desired outcome.
Posterior lumbar fusion; Transforaminal lumbar interbody fusion (TLIF)
Transforaminal lumbar interbody fusion (TLIF) is a procedure that fuses the anterior and posterior columns of the spine through a single posterior approach. This procedure is usually combined with a decompressive laminectomy to take pressure off the nerves, and the fusion is added to stabilize the spine when necessary, such as when a spondylolisthesis is present.
In this procedure, a 2-5 inch incision is made in the midline of the lower back. First, a laminectomy is performed, as described here. Then, the nerve roots are gently held out of the way, while the disc is removed, and a cage and bone graft are placed inside the disc space to achieve a spinal fusion. Additional bone graft material is also placed along the back of the spine, and screws are placed for enhanced stability. Most patient note immediate relief of the preoperative leg pain, and improvement in the back discomfort as the fusion heals over the ensuing months after surgery. Usually, a one to three night hospital stay is necessary after this operation.