Lumbar Fusion Animation
Spine Surgery to Treat Low Back Pain
Lumbar fusion joins two or more vertebral bodies together. It is performed using instrumentation and bone graft to stop motion and stabilize the low back.
Instrumentation provides immediate rigid fixation by implanting one or more interbody devices (eg, cages), pedicle screws, plates, or rods. There are many types of fixation devices.
Types of bone graft include:
- Autograft—the patient’s own bone (that’s what the auto- means). It may be collected during spine surgery and/or harvested from a hip bone (iliac crest).
- Allograft is donor bone from a bone bank.
- Demineralized bone matrix (DBM) is allograft cortical bone (compact bone). It is available as granules, putty, gel, and strips.
- Bone morphogenetic protein (BMP) is a man-made protein. It is mixed and soaked into a collagen (human protein) sponge the body resorbs as bone heals.
- Some types of bone graft are combined.
Minimally Invasive Lumbar Fusion vs Open Spine Surgery
Types of lumbar fusion procedures include minimally invasive and open spine surgery.
Minimally invasive surgery offers select patients smaller incisions, less blood loss, often same day surgery, less post-operative pain, and quicker recovery. Minimally invasive surgery utilizes specialized instruments and techniques to accomplish the same goal as a similar traditional open procedure—stabilizing the spine and reducing pain and/or deformity.
Traditional open spine surgery involves one or more long incisions.
Lumbar fusion and instrumentation may be performed in different ways. Some of these procedures are listed below.
- Anterior lumbar interbody fusion (ALIF) is performed from the front of the body.
- Posterior lumbar interbody fusion (PLIF) is performed from the back of the body.
- Transforaminal interbody fusion (TLIF) is performed from the side at an angle (oblique).
- Posterolateral fusion (PLIF) involves an incision made down the center (midline) of the low back.
- Pedicle Screw Fixation (PSF) is performed from the back of the spine (posterior). Special screws are implanted into the pedicles (Figure 1); the screws serve as anchors for rods. The pedicles are dense finger-like bones that extend from the back of a vertebral body.
Figure 1: Pedicle screw fixation illustration
Depending on the purpose and goals of surgery, lumbar fusion is combined with other procedures.
- Discectomy: partial or total removal of a damaged disc (eg, a herniated disc).
- Foraminotomy: decompression of a spinal nerve by access to the neuroforamen. The neuroforamen is a nerve passageway naturally created by disc height and space between two vertebral bodies. Spinal stenosis can cause narrowing of the neuroforamen and compress nerve structures.
- Laminotomy/laminectomy: partial or total removal of the lamina; a thin bone covering access to the spinal cord and nerve rootlets.
- A combination of procedures.
A Possible Cause of Lumbar Instability
There are many reasons a patient may need a lumbar spinal fusion, but here is an example.
Degenerative disc disease (DDD) is common, especially in older adults. Early changes in the spine’s structure and mechanics begin at the cellular level. One or more spinal discs dry out and shrink in size. As a disc dries out, it loses its strength, pliability, and elasticity. It becomes more susceptible to damage from physical forces such as gravity, compression, tension, and torque.
Small tears may begin to develop in the outer rim (annulus fibrosis) of the disc. The disc space between two vertebral bodies begins to narrow and compresses adjacent nerves causing inflammation and pain. Bone spurs (osteophytes) may grow and contribute to nerve impingement.
Your primary care doctor may refer you to a spine specialist, such as an orthopaedic spine surgeon or neurosurgeon for further evaluation, diagnosis, and treatment. Fortunately, most patients do not need lumbar fusion or any spine surgery, and rarely is spine surgery an emergency procedure. Rather, non-invasive or less invasive operative therapies are tried first. Medications, spinal injections, and/or passive and active physical therapy may be combined to maximize benefits.
However, if a lumbar spinal fusion is recommended, you now know from this animation what to expect.