Transforaminal Lumbar Interbody Fusion Surgery
Lumbar fusion surgery is performed after all conservative management options have been tried without satisfactory results. Various conditions that may be treated with fusion surgery are:-
- Degenerative disk disease may cause symptoms of back pain and radiculopathy. With advancing age, there may be a loss of disk height resulting in subsequent segment instability. The body tries to re-align by enlargement of ligaments and bony structures that may impinge upon the neural structures.
- Recurrent intervertebral disc herniations may result after traumatic events or degenerative conditions. The herniated disk may compress the exiting or traversing nerve roots causing symptoms of radiculopathy.
- Spondylolisthesis occurs as a result of misplaced vertebrae due to developmental, isthmic, or degenerative causes. The displaced vertebrae may cause back pain and symptoms of radiculopathy or neurogenic compression.
- Spinal canal stenosis occurs as a result of narrowing of the vertebral canal or the neural foramen.
- Failed back surgery involves the continuation of symptoms of back pain or radiculopathy after prior spine surgery. The failure of surgery may be due to implant failure, adjacent level degeneration, wrong diagnosis, incomplete surgery, etc.
The surgery is performed under general anesthesia, and the patient is placed on his/her abdomen. The surgeon gives a skin incision slightly towards the body’s side (about 4cm from the midline) over the involved segment. A metallic wire is passed under fluoroscopic guidance towards the facet joint complex.
Serial dilators are passed over the wire to create a muscle splitting rather than cutting exposure. The tubular retractors are then used to visualize the involved segment.
The surgeon then decompresses the segment by removing the facet joint and by performing laminectomy. The intervertebral disk material is removed from the involved side. Any other tissue compressing upon the neural tissue is removed.
The surgeon then introduces a cage between the involved vertebrae after the endplate preparation. The cage may be made of metal alloy or high-grade plastic such as PEEK (poly ether-ether ketone). The bone cage functions to maintain the disc space between the two vertebrae.
The bone cage is filled with bone graft material. The bone graft may be taken from the patient’s pelvis during the surgery or maybe utilized from a bone bank. The bone graft ensures speedy union between the vertebrae.
Mirror incisions are made on the other side to introduce pedicle screws. Rods are tightened over the pedicle screws to support the arthrodesis in the front. The screw and rod construct also decompress the vertebrae by distraction.
Throughout the surgery, care is taken to protect the nerve roots and the dural sac from inadvertent damage. The incisions are closed in layers, and the patients may go home after a day’s stay at the hospital or may go home the same day if a minimally invasive technique is used.
Although the risk of complications remains relatively low, there may be potential complications of infection, blood loss, nonunion of the fusion, implant failure, blood clots, etc. The operating surgeon will discuss all the potential risks and complications with the patient before the surgery.
The majority of the patients are advised to walk the next day of the surgery and resume their daily activities. They are advised against the lifting of heavyweights and sudden bending or twisting movements. Physical therapy is initiated to strengthen the back muscles and improve flexibility. Pain medications may be used in the initial postoperative period.
Benefits of TLIF
The transforaminal approach utilized the entry from the side of the back. The entry prevents cutting of the back muscles to reach the involved segment. The muscles and other soft tissues are instead separated with the use of tubular dilators. This has been shown to improve the postoperative recovery period.
Patients treated with the TLIF approach experience less postoperative pain and require fewer doses of pain medications. They can also participate in physical therapy earlier than the patients treated with the traditional posterior approach.
A large amount of bone graft can be placed from the side of the spine that ensures a steadier fusion. The retraction of the dural sac and the nerve roots is minimum, so the chances of nerve injury and dural tear are far less with the transforaminal approach.
The lateral trajectory used in the transforaminal approach can also be used in patients with prior spine surgery. The approach may be used in patients with far lateral disc herniations and instability.
The transforaminal approach is contraindicated in patients with metabolic bone disorders such as osteoporosis. The TLIF surgery is also not indicated in patients with disc infection, multilevel disease, extensive scarring from prior surgery. The approach is also not indicated in patients with complete disc involvement as through TLIF, the surgeon can reach only one side of the disc.