Lumbar surgery refers to any type of surgery in the lumbar spine or lower back. Lumbar surgery is often performed to treat compressed nerves in the lumbar spine caused due to spondylosis (a type of arthritis spur caused by wear and tear of the spine), herniated or slipped disc and spinal stenosis which is a narrowing of the spaces within the spine, resulting in an increased pressure on the nerves that travel through the spine. These spine conditions usually cause pain that are often described as sharp, numbness or tingling. Pain usually radiates from the back to the buttocks and the legs. Weakness of affected leg might be also present with inability to stand or walk for a long distance. Microdecompression surgery of lumbar spine is usually performed through a small surgical incision by using microscope. The purpose is to access the affected part of spine in order to create more space within the spinal canal and remove the degenerative disc and bone spur. This procedure aims to alleviate the nerves from compressing pressure causing radiating leg pain and numbness. This procedure, however, may provide minimal benefits in patient with severe or chronic back pain due to unstable spine such as ‘spondylolisthesis’ or bone slip. In this group of patient, additional procedure of fusing the lumbar spine segment may also be needed to enhance the stability of the spine and at the same time to reduce back pain.
Evolution of Transforaminal Lumbar Interbody FusionIn the past, traditional surgery called open laminectomy was widely conducted via large surgical incision at the back to remove the lamina — the back part of a vertebra that covers the spinal canal. In order to access the affected part of the spine, the spine surgeon needs to make long incision in the back over the affected spine and dissect large part of the back muscles. The surgeon also removes the herniated portion of the disc and bony part of spine causing nerve compression. A metal screw is then inserted to stabilize the spine (Posterior pedicle screw fixation). Biomechanic studies later indicate that 70-80% of the body weight is transferred to the frontal part of the lumbar spine which consists of bony part and disc in the middle. Therefore, to achieve better outcomes with improved spinal stability, fusion in the disc space (Interbody fusion) in which the disc is removed and replaced with spacer (filled with bone graft or bone substitute) should be performed concurrently with posterior pedicle screw fixation. The most commonly used technique is called open Transforaminal Lumbar Interbody Fusion or open TLIF. During open TLIF with open incision, facet joints which are a set of joints between two adjacent vertebrae will be cut and the slipped or damaged intervertebral disc is removed. Then spinal fusion connecting two or more damaged vertebrae using spacer with bone grafts, metal rods and screws is done. Major drawback of open TLIF approach, however, is the extensive muscle dissection and retraction, leading to significant muscle injury, resulting in more postoperative back pain.
Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS TLIF)Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS TLIF) is a technique developed to make lumbar fusions less invasive compared to Transforaminal Lumbar Interbody Fusion or open TLIF, yielding more favorable results both intraoperatively and post operatively. MIS TLIF technique includes:
- Before surgery begins, an inch long incision is made on the skin at the back (paraspinal incision). The spine surgeon inserts a small noncollapsable tube through the skin until it rests on the spine. Through this small tube, a special microscope will be used to magnify the surgical site allowing for a clear visualization of the intervertebral disc and surrounding nerves. A degenerated intervertebral disc is removed and interbody fusion can be done by inserting a spacer filled with bone graft or bone substitute into the disc space. The surgeon can then perform the entire TLIF procedure using a microscope through smaller incision site.
- After fusion at disc space is done, the next step is to stabilize the spine segment via inserting a screw through small stab skin incisions (Percutaneous pedicle screw fixation). This process is done using ‘The O-arm’ which is an intraoperative 3D imaging system combined with navigator system that helps to verify the accurate locations of screws and rods to be put through small stab skin incisions. As a result, surgical outcome is more effective, result in high degree of safety and accuracy with fewer traumatic damages to surrounding tissues, muscles and nerves. MIS TLIF takes approximately 2-3 hours.