What is a fusion operation?
Fusion simply means joining two bones together in a solid manner, thus preventing future movement between the bones.
Lumbar spine fusions can be performed from the front of the spine, (anterior approach) or from the back of the spine, (posterior approach). On occasions they may need a combined approach from the front and the back.
Bone or bone substitutes are used to fuse the bones together. Within the spine the bone graft may be placed posteriorly,between adjacent transverse processes (Posterolateral Fusion), or anteriorly, between the vertebral bodies (Interbody fusion). Certain techniques allow both fusions to be performed, resulting in a circumferencial fusion or 360 degree fusion. The bone may be stabilized with instrumentation, while the bone graft knits together. With a posterior fusion this involves the insertion of screws into the bone, through the pedicles
Do I need a fusion operation?
Fusions are performed within the lumbar spine for a variety of reasons.
Back pain, may be caused by a degenerate lumbar disc. Under these circumstances a lumbar fusion aims to prevent movement between the adjacent vertebrae and so reduce this pain.
Instability of the spine may result in a spondylolisthesis, movement of one vertebra relative to the adjacent vertebra, which may lead to back pain or pressure on the nerves, which may cause leg pain. The spondylolisthesis may be reduced and fused, or under certain circumstances, fused in its slipped position.
Lumbar decompression surgery is used to relieve pressure on the nerves within the spine. If the spine is unstable or the process of the decompression results in the spine becoming unstable, then the decompression may be combined with a spinal fusion.
What other treatment options are there?
Injections into the spine
These procedures are used when pain relief is required, yet surgery is not immediately indicated. Leg pain may be relieved by an epidural or a nerve root block and back pain may be improved with facet joint injections. (See spinal injections)
Non fusion surgery
The spine may be stabilized without fusing the spine. Techniques include Dyneses where by pedicle screws are placed into adjacent vertebrae and then connected together by a non-rigid structure. This has the advantage of maintaining movement within the spine, but may not be suitable for every condition. Suitability for the Dyneses procedure depends on the type of problem within the spine and the severity of the condition.
Types of lumbar Fusion
Posterior lumbar fusion
Bone is placed between the transverse processes (T.P.) of adjacent vertebrae. (There are two T.P.s, one on each side of the vertebra, which project outwards). The bone placed between the two adjacent vertebrae heals to produce a solid fusion between adjacent vertebral bodies within the spine.
Frequently the spine is stabilised with spinal instrumentation while the bone heals. This can be performed in a variety of ways depending upon the precise indications for the surgery.
