Posterior Spine Fusion
The goal of posterior spinal fusion is to stabilize one or more motion segments of the spine. Posterior spine fusion may be recommended to treat back pain caused by degenerative joints or discs. Spinal fusion may also be recommended for patients with spinal instability or spinal deformities. When a spine fusion is performed, bone graft is used to join two or more vertebra together. The vertebrae grow together or “mend” during the healing process, much like a broken bone healing in a cast. In some cases, spinal instrumentation (screws and rods) are utilized to increase the chances of spinal fusion. These metal implants can help to correct the deformity and hold the spine in appropriate stable location while the bone graft heals and the spine begins to fuse.
ANATOMY:
The spine is composed of individual bones called vertebra. The vertebra are stacked one on top of another and cushioned in between by the intervertebral disc. A circle of bone extends from the vertebral body back around the sac of nerves and spinal cord. This circular protective tube of bone called the spinal canal protects the spinal cord and spinal nerves. In the lumbar spine the spinal nerves exit the spinal canal between the vertebrae at each level. Two nerves exit each level, one on the left and one on the right. These nerves exit through openings called foramina [Figure 1]. A transforaminal lumbar interbody fusion is performed through a posterior incision on the back of the lumbar spine. The procedure can be performed through a traditional open incision or a minimally invasive procedure depending on the patient and the condition to be treated.
Figure 1:
POSTERIOR SPINE FUSION:
Posterior spine fusion is performed from the back of the spine. The approach can be used to perform fusion and can also be used to remove problematic disc or to relieve pressure on the nerves of the spinal canal. With the standard posterior approach, an incision is made in the middle of the back over the area of the spine to be fused. The muscles are then moved to the side so the surgeon can see the back surface of the vertebral bones. Spinal instrumentation increases the stability of the bones after surgery and the chances that a successful fusion will occur. At the end of the surgery, the muscles are then replaced to their original location at the completion of the operation. Minimally invasive techniques can allow the surgeon to perform similar procedures with less movement or disruption of the muscles and tissues supporting and surrounding the spine [Figure 2].
Figure 2:
BONE GRAFTING:
There are multiple options for bone graft material for spinal fusion. The experts at the Virginia Spine Institute do not usually harvest hip bonegraft or iliac crest bone graft for most spinal fusion procedures. Taking hip bone graft increases postoperative pain and prolongs healing. Surgeons at the Virginia Spine Institute may use a combination of your own bone from the area of the spine as well as Bone Morphogenetic Protein (BMP II), a genetically engineered substance that stimulates bone healing. For some patients additional donated and prepared bone allograft is also utilized.
POST SURGERY HOSPITAL COURSE:
Patients usually remain in the hospital one to three days after posterior lumbar fusion surgery. Postoperative pain control is achieved with the use of IV pain medication, epidural pain medication and oral pain medications. Patients are discharged home on oral pain medication. A catheter may placed in the bladder and is removed in the first one to two days after surgery. Patients begin a physical therapy walking program the day after surgery and a physical therapist teaches the patient to get out of bed and walk safely. Patients need to be comfortable with walking, climbing stairs and getting in and out of bed before going home. The final goal is to make sure the gastrointestinal and urinary systems are working appropriately. Patients must be able to eat a solid meal and urinate without difficulty prior to leaving the hospital.
SUMMARY:
Posterior lumbar fusion surgery is an approved and effective method for fusing the lumbar spine. The goal of surgery is to improve pain and correct spinal deformity and instability. Complications occur but are not common. The majority of patients are satisfied with their pain relief and the results of their surgery. All patients should review their specific condition and surgical plan with their surgeon prior to the surgical procedure. It is important that all patients having spine fusion surgery are physically and psychologically prepared for their procedure. All patients should stop smoking prior to their surgical procedure. Please review additional details with your surgeon prior to the procedure.
