Extreme Lateral Interbody Fusion

Extreme lateral or direct lateral interbody fusion is a surgical technique performed from the side of the body for the management of lumbar spine disease. The technique offers significant advantages over the traditional approach and is used to treat a wide range of diseases such as spondylolisthesis, disc herniation, etc.

Lumbar interbody fusion surgery is a surgical technique used to fuse the two diseased vertebrae together. The intervening intervertebral disk is removed during the surgery. The fusion of the vertebrae is achieved by using a bone graft which heals to form a solid bony bridge between the vertebrae. A cage made of polyethylene or metal alloy is inserted in between the vertebrae to maintain the disc height and decompress the neural structures. During the surgery any structures impinging upon the dural sac/spinal nerves are also removed.

Bone Model showing XLIF.

Traditionally, the surgery is performed from the back or the front of the spine. In posterior lumbar interbody fusion (PLIF) the surgeon gives an incision in the back of the spine and gains access to the intervertebral disc by carefully cutting structures. Similarly in anterior lumbar interbody fusion (ALIF), the surgeon gains access to the lumbar spine through an incision in the abdomen and by carefully retracting the abdominal organs and major blood vessels.

Extreme lateral interbody fusion (XLIF) on the other hand utilizes an incision from the side of the body. The spine surgeon uses two small incisions in the flanks and guides the instruments through the hole. Instead of cutting, the surgeon uses a tubular dilator that separates the tissues.

Upon reaching the diseased segment, the surgeon uses special instruments to remove the intervertebral disc. Any tissues impinging upon the dural sac/nerves are also removed to decompress the neural structures. The surgeon then introduces a cage to maintain the disc height and further decompress the segment. The cage is filled with bone graft material. Additional screws, rods or plates may be used to provide stability to the fusion construct.

Instruments used in XLIF and Interbody spacer.

The positions of implants and bone cage are confirmed on an intraoperative X-ray and the incisions are closed in layers. As the procedure involves less cutting and safer approach, the entire procedure takes significantly less time than the traditional approaches.

Through the lateral approach, the cutting of the sensitive back muscles is avoided as done in the posterior approach. Similarly there is no cutting and manipulation of ligaments, nerves, dural sac, etc during the lateral approach. This results in reduced post operative pain and reduced risk of inadvertent injury to the nerves and the dural sac. The patients report a faster rehabilitation as healing time is reduced secondary to less cutting of tissues.

Similarly, the lateral approach leads to less risk of injury to the abdominal organs and the major blood vessels as compared to the anterior approach. The risk of excessive bleeding is reduced and the patients rapidly return to their normal activity. There is also minimum scarring of the tissues as compared to the traditional approach.

The XLIF procedure may be performed in patients requiring interbody fusion of the lumbar spine above the L5-S1 level. The various conditions that may be treated are herniated intervertebral disc, mild spondylolisthesis, degenerative disc disease with instability, post-laminectomy instability, failure of lumbar disc replacement, etc.

The attending orthopaedic spine surgeon determined if the patient is a right candidate for extreme lateral interbody fusion. The surgeon extracts a thorough history of the events preceding the symptoms and performs a physical examination. Radiological tests are done to look for both the bony and the soft tissue structures of the spine.

Patients with lumbar disease of the L5-S1 segment and in some cases L4-L5 segments are not good candidates for XLIF. Also in patients with morbid obesity, infection, osteoporosis, and significant deformity and spondylolisthesis, XLIF is not indicated.

As with any spine surgery, there may be potential complications such as blood clots, infection, excessive bleeding, inadequate fusion, nonunion of fusion, blood vessel/nerve damage, etc. The risk and complications are less as compared to the traditional approaches and a vast majority of patients benefit from the reduced operative time and a faster recovery period.