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Spinal Fusion Glossary

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Understanding spinal fusion can be difficult and confusing. There are several different types of fusion, as well as different surgical approaches to perform the operation. Your surgeon will review the options and answer your questions in detail.

This glossary of words and abbreviations has been developed to help you better understand the different spinal fusion surgeries.

For more detailed information about spine anatomy: Spine Basics

Regions of the spine

Spinal fusion can be performed in any region of the spine.

Incision Site

Surgeons can reach the spine by making an incision (cut) in different places on your body. Incision sites are often described by location as:

  • Anterior. This term refers to the front of your body. In spinal fusion surgery, an anterior fusion in the lumbar spine is done by making an incision in the abdomen (belly).  For a  fusion in the cervical spine, the incision is made in the front of the neck.
  • Posterior. This refers to the back part of your body. If you are having a posterior fusion in the lumbar spine, you will lie on your belly during the operation and your surgeon will make the incision in your lower back. If the fusion is in your cervical spine, the surgeon will make the incision in the back of your neck.
Posterior incision site

A posterior incision site in the lower back.

  • Lateral. This refers to the side part of your body. Surgeons can reach certain parts of the lower back or upper back (thoracic spine) by making an incision in your side. A lateral approach is rarely used for the neck.
  • Anterolateral. This refers to an area in between the anterior and lateral parts of your body. An anterolateral approach is typically used when accessing the lower back.

Location of Fusion in the Spine

Two or more bones (vertebrae) in your spine must heal together into a single, solid bone for a successful fusion. The vertebrae can be joined either between the transverse processes or in the disk space.  

Intertransverse or posterolateral. This is the part of the lumbar spine between the transverse processes on the sides of the vertebra.

Surgeons most often reach this area by making an incision in the back. This type of fusion is called:

  • Posterior (from the back) posterolateral (specific spinal anatomy involved)
    Fusion. This procedure is often referred to as a PLF.

In a spinal fusion, the vertebrae can be joined either between the transverse processes (left) or in the disk space between the vertebrae (right).

Interbody. This is the part of the spine where the disk is present, between the bones (vertebrae). An interbody fusion can be performed with different approaches:

  • Anterior (from the belly) Lumbar (part of the spine being operated upon) Interbody (in the disk space) Fusion. You may see this written as an ALIF.
  • Posterior (from the back) Lumbar (part of the spine being operated upon) Interbody (in the disk space) Fusion or PLIF.
  • A different type of PLIF is called transforaminal. Although the spine is still reached through an incision in the back, the disk space is approached from the side. Transforaminal (from the back) Lumbar (part of the spine being operated upon) Interbody (in the disk space) Fusion or TLIF.
  • Lateral (from the side) Lumbar (part of the spine being operated upon) Interbody (in the disk space) Fusion (specific surgery being done). This type of surgery is often described as a Direct lateral or Extreme lateral approach (DLIF or XLIF).
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Last Reviewed

June 2018

Contributed and/or Updated by

Daniel K. Park, MD

Peer-Reviewed by

Stuart J. Fischer, MD

AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.