Posterior Lumbar Fusion (PLF)

Overview and Indications

Posterior Lumbar Fusion (PLF) is the general term used to describe the technique of surgically mending two (or more) lumbar spine bones together along the sides of the bone. Bone graft is placed along side the spine bones (not in between the disc spaces, which is called an interbody fusion), and ultimately fuses together. PLF may be performed in conjunction with or without a posterior decompression (laminectomy) and/or instrumentation (use of metal screws/rods). Typically, metal screws and rods are placed so as to impart immediate stability while the bone mends and to increase the fusion rate (percentage of patients where the bone successfully mends together).

PLF is commonly performed for a variety of spinal conditions, such as spondylolisthesis, spinal fractures, tumors, infections, and scoliosis, among others.

Surgical Technique

The surgery is performed utilizing general anesthesia. A breathing tube (endotracheal tube) is placed and the patient breathes using a ventilator during the surgery. Preoperative intravenous antibiotics are given. Patients are positioned in the prone (lying on the stomach) position, generally using a special operating table/bed with special padding and supports. The surgical region (low back area) is cleansed with a special cleaning solution. Sterile drapes are placed, and the surgical team wears sterile surgical attire such as gowns and gloves to maintain a bacteria-free environment.

A 4-8 centimeter (depending on the number of levels) longitudinal incision is made in the midline of the low back, directly over the spinal levels to be fused. The fascia and muscle is gently divided in the midline, and retractors are used to allow the surgeon to visualize the posterior (back part) vertebral arches. After the retractor is in place, an x-ray is used to confirm that the appropriate spinal level(s) is identified.

The lamina, facet joints, and transverse processes are exposed on both sides of the spinous processes. At the levels to be fused, the facet joints and transverse processes are decorticated and bone graft is placed along side of the vertebrae. Two small pedicle screws or hooks are placed at each spinal level of the fusion, and connected by titanium rods.

A complete or partial laminectomy (removal of lamina portion of bone) and foraminotomy (removal of bone spurs near where the nerve comes through the hole of the spine bone) may also be performed if necessary, thus allowing the nerves to return to their normal size and shape when the compressive lesions are removed. The nerve roots and neurologic structures are protected and carefully retracted, so that the bone spurs can be visualized and removed. Small dental-type instruments and biting/grasping instruments (such as a pituitary rongeur and kerrison rongeur) are used to remove the arthritic, hypertrophic (overgrown) bone spurs and ligamentum flavum. All surrounding areas are also checked to ensure no compressive spurs or disc fragments are remaining.

The wound area is usually washed out with sterile water containing antibiotics. The deep fascial layer and subcutaneous layers are closed with a few strong sutures. The skin is closed using stitches or surgical staples. A sterile bandage is applied, and is changed daily while in the hospital.

The total surgery time is approximately 2 to 5 hours, depending on the number of spinal levels involved.

Post-Operative Care

Most patients are usually able to go home 2-5 days after surgery. Before patients go home, physical therapists and occupational therapists work with patients and instruct them on proper techniques of getting in and out of bed and walking independently. Patients are instructed to avoid bending at the waist, lifting (more than five pounds), and twisting in the early postoperative period (first 2-4 weeks) to avoid a strain injury. Patients can gradually begin to bend, twist, and lift after 4-6 weeks as the pain subsides and the back muscles get stronger.

Brace

Patients are generally not required to wear a back brace after surgery. Occasionally, patients may be issued a soft or rigid lumbar corset that can provide additional lumbar support in the early postoperative period, if necessary. Patients undergoing multilevel fusion surgery for scoliosis, kyphosis, spinal infections or tumors are typically issued a custom molded thoracolumbar brace.

Wound Care

The wound area should remain covered with a gauze bandage secured in place with tape. The area should be kept clean and dry. The bandage should generally be changed every 1-2 days, especially after showering.

Shower/Bath

Patients can shower immediately after surgery, but should keep the incision area covered with a bandage and tape, and try to avoid the water from water hitting directly over the surgical area. After the shower, patients should change the bandage, and dry off the surgical area. The dressing should otherwise be changed every 2-3 days when at home. Patients should not take a bath until the wound has completely healed, which is usually around 2 weeks after surgery.

Driving

Patients may begin driving when the pain has decreased to a mild level, which usually is between 7-14 days after surgery. Patients should not drive while taking pain medicines (narcotics). When driving for the first time after surgery, patients should make it a short drive only and have someone come with them, in case the pain flares up and they need help driving back home. After patients feel comfortable with a short drive, they can begin driving longer distances alone.

Return to Work and Sports

Patients may return to light work duties as early as 2-3 weeks after surgery, depending on when the surgical pain has subsided. Patients may return to moderate level work and light recreational sports as early as 3 months after surgery, if the surgical pain has subsided and the back strength has returned appropriately with physical therapy. Patients who have undergone fusion at only one level may return to heavy lifting and sports activities if the surgical pain has subsided and the back strength has returned appropriately with physical therapy. Patients who have undergone fusion at two or more levels are generally recommended to avoid heavy lifting, laborious work, and impact sports.

Doctor's Visits and Follow-Up

Patients will return for a follow-up visit to see the doctor approximately 12-14 days after surgery. The incision will be inspected. The incision will be inspected and the stitches or staples will be removed. Patients will usually return to see Dr. Spoonamore or Dr. Smith every 4-6 weeks thereafter, and an x-ray will be taken to confirm the fusion area is stable and healing appropriately. At 8-12 weeks after surgery, patients will be given a prescription to begin physical therapy for gentle back exercises.

Results and Outcome Studies

The results of posterior lumbar fusion (PLF) surgery in the treatment of symptomatic spondylolisthesis, spinal fractures, tumors, infections, and scoliosis are generally excellent. Numerous research studies in medical journals demonstrate greater than 85-96% good or excellent results from PLF surgery. Most patients are noted to have a significant improvement of their back pain and return to many, if not all, of their normal daily and recreational activities.

Selected Bibliography

Bjarke Christensen F, Stender Hansen E, Laursen M, Thomsen K, Bunger CE. Long-term functional outcome of pedicle screw instrumentation as a support for posterolateral spinal fusion: randomized clinical study with a 5-year follow-up. Spine. 2002;27:1269-77.

Deguchi M, Rapoff AJ, Zdeblick TA. Posterolateral fusion for isthmic spondylolisthesis in adults: analysis of fusion rate and clinical results. J Spinal Disord. 1998;11:459-64.

Fritzell P, Hagg O, Wessberg P, et al.. 2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine. 2001;26:2521-32.

Lehmann TR, Spratt KF, Tozzi J, et al.. Long-term follow-up of lumbar fusion patients. Spine. 1987;12:97-104.

Lorenz M, Zindrick M, Schwaegler P, et al.. A comparison of single-level fusions with and without hardware. Spine. 1991;16:S455-58.

Seitsalo S, Osterman K, Hyvarinen H, et al.. Severe spondylolisthesis in children and adolescents. A long-term review of fusion in situ. J Bone Joint Surg Br. 1990;72:259-65.

Thomsen K, Christensen FB, Eiskjaer SP, Hansen ES, Fruensgaard S, Bunger CE. The effect of pedicle screw instrumentation on functional outcome and fusion rates in posterolateral lumbar fusion. Spine. 1997;24:2813-22.

Zdeblick TA. A prospective, randomized study of lumbar fusion: preliminary results. Spine. 1993;18:983-91.