Modern Spine Fusion Techniques

Fig 1: Posterolateral gutter fusion surgery (view larger)

The two primary types of medical devices used in a spinal fusion surgery include pedicle screws and anterior interbody cages or spacers. When it has been determined that a spine fusion is appropriate, the surgical technique utilized may vary.

Posterior approaches to spine fusion

The surgical techniques that have historically been used the most comprise spine fusion surgery that is approached posteriorly, or from the back (vs. anteriorly, or through the abdomen). There are three main posterior fusion techniques (all three are usually performed with pedicle screw fixation):

• Posterolateral gutter fusion surgery. This type of spinal fusion involves placing bone graft in the posterolateral portion of the spine (a region just outside the back of the spine). This type of fusion has a long history and has been the most commonly used approach (see Figure 1).
• Posterior lumbar interbody fusion (PLIF) surgery. A PLIF involves placing bone graft and/or spinal implant (e.g. cage) directly into the disc space in the front of the spine.
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• Transforaminal lumbar interbody fusion (TLIF) surgery. A TLIF is essentially like an extended PLIF, as it also involves expanding the disc space by removing one entire facet joint (whereas a PLIF usually involves gaining access to the disc space by removing a portion of the facet joints on each side of the spine).

Anterior approaches to spine fusion

An anterior approach (from the front) to spine fusion allows the surgeon to place bone directly in the space between the vertebrae where the disc had been. Because approximately 80% of the forces of the spine are borne through the disc space, it is much more likely that a solid fusion will be achieved and patients will have pain relief if the fusion includes the disc space. There are two primary techniques to accomplish this.

• Anterior/posterior lumbar fusion surgery. An anterior/posterior fusion surgery is typically performed through an incision in the abdomen, with removal of the disc and placement of bone graft where the disc material has been removed. A separate incision is made in the back to place the pedicle fixation and bone graft.

  This approach may include a large amount of trauma to the muscles, a long hospital stay, and may at times be associated with a fair amount of blood loss. However, in cases where there is a lot of instability, an anterior/posterior fusion surgery can be necessary as it provides the greatest amount of stability.

• Anterior lumbar interbody fusion (ALIF) surgery. An anterior lumbar interbody fusion is a surgery technique that involves the placement of bone graft with a plate or secored spacer or bone graft with an anterior interbody cage within the disc space. The most efficient way to place this is through the abdomen into the disc space.

  Most commonly, persons who have undergone this spine fusion surgery are able to return to their activities more rapidly. This type of approach can be used in cases where there is not a lot of associated instability and the disc space is narrow. The results of stand alone anterior fusions are not as good for multilevel constructs.

• Article written By:
• John E. Sherman, MD

September 8, 2006

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