Spinal fusion
Encyclopedia
Spinal fusion, also known as spondylodesis or spondylosyndesis, is a surgical technique
used to join two or more vertebrae. Supplementary bone tissue, either from the patient (autograft) or a donor (allograft), is used in conjunction with the body's natural bone growth (osteoblast
ic) processes to fuse the vertebrae.
Fusing of the spine is used primarily to eliminate the pain
caused by abnormal motion of the vertebrae by immobilizing the faulty vertebrae themselves, which is usually caused by degenerative conditions. However, spinal fusion is also the preferred way to treat most spinal deformities, specifically scoliosis
and kyphosis
.
region of the spine
, but it is also used to treat cervical
and thoracic
problems. The indications for lumbar spinal fusion are controversial. People rarely have problems with the thoracic spine because there is little normal motion in the thoracic spine. Spinal fusion in the thoracic region is most often associated with spinal deformities, such as scoliosis
and kyphosis
.
Patients requiring spinal fusion have either neurological deficits or severe pain which has not responded to conservative treatment.
Conditions where spinal fusion may be considered:
Posterolateral fusion places the bone graft between the transverse processes in the back of the spine. These vertebrae are then fixed in place with screws and/or wire through the pedicles
of each vertebra attaching to a metal rod on each side of the vertebrae.
Interbody fusion places the bone graft between the vertebra in the area usually occupied by the intervertebral disc
. In preparation for the spinal fusion, the disc is removed entirely, for example in ACDF
. A device may be placed between the vertebra to maintain spine alignment and disc height. The intervertebral device may be made from either plastic or titanium. The fusion then occurs between the endplates
of the vertebrae. Using both types of fusion is known as 360-degree fusion. Fusion rates are higher with interbody fusion.
Three types of interbody fusion are:
In most cases, the fusion is augmented by a process called fixation, meaning the placement of metallic screws (pedicle screws often made from titanium), rods or plates, or cages to stabilize the vertebra to facilitate bone fusion. The fusion process typically takes 6–12 months after surgery. During this time external bracing (orthotics) may be required. External factors such as smoking, osteoporosis, certain medications, and heavy activity can prolong or even prevent the fusion process. If fusion does not occur, patients may require reoperation.
Some newer technologies are being introduced which avoid fusion and preserve spinal motion. Such procedures, such as artificial disc replacement, are being offered as alternatives to fusion, but have not yet been adopted on a widespread basis in the US. Their advantage over fusion has not been well established. Minimally invasive techniques have also been introduced to reduce complications and recovery time for lumbar spinal fusion.
Orthopedic surgery
Orthopedic surgery or orthopedics is the branch of surgery concerned with conditions involving the musculoskeletal system...
used to join two or more vertebrae. Supplementary bone tissue, either from the patient (autograft) or a donor (allograft), is used in conjunction with the body's natural bone growth (osteoblast
Osteoblast
Osteoblasts are mononucleate cells that are responsible for bone formation; in essence, osteoblasts are specialized fibroblasts that in addition to fibroblastic products, express bone sialoprotein and osteocalcin.Osteoblasts produce a matrix of osteoid, which is composed mainly of Type I collagen...
ic) processes to fuse the vertebrae.
Fusing of the spine is used primarily to eliminate the pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
caused by abnormal motion of the vertebrae by immobilizing the faulty vertebrae themselves, which is usually caused by degenerative conditions. However, spinal fusion is also the preferred way to treat most spinal deformities, specifically scoliosis
Scoliosis
Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
and kyphosis
Kyphosis
Kyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
.
Reasons for spinal fusion
Spinal fusion is done most commonly in the lumbarLumbar
In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum ...
region of the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
, but it is also used to treat cervical
Cervical vertebrae
In vertebrates, cervical vertebrae are those vertebrae immediately inferior to the skull.Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also...
and thoracic
Thoracic vertebrae
In human anatomy, twelve thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. They are intermediate in size between those of the cervical and lumbar regions; they increase in size as one proceeds down the spine, the upper...
problems. The indications for lumbar spinal fusion are controversial. People rarely have problems with the thoracic spine because there is little normal motion in the thoracic spine. Spinal fusion in the thoracic region is most often associated with spinal deformities, such as scoliosis
Scoliosis
Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
and kyphosis
Kyphosis
Kyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
.
Patients requiring spinal fusion have either neurological deficits or severe pain which has not responded to conservative treatment.
Conditions where spinal fusion may be considered:
- degenerative disc diseaseDegenerative disc diseaseDegeneration of the intervertebral disc, often called "degenerative disc disease" of the spine, is a condition that can be painful and can greatly affect the quality of one's life...
- spinal disc herniation
- discogenic painPainPain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
- spinal tumorTumorA tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
- vertebral fracture
- scoliosisScoliosisScoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...
- kyphosisKyphosisKyphosis , also called roundback or Kelso's hunchback, is a condition of over-curvature of the thoracic vertebrae...
(i.e, Scheuermann's diseaseScheuermann's diseaseScheuermann’s disease is a self-limiting skeletal disorder of childhood. It is also known as Sherman's Disease, Scheuermann’s kyphosis , Calvé disease and Juvenile Osteochondrosis of the Spine. It is named after Holger Werfel Scheuermann...
) - spondylolisthesisSpondylolisthesisSpondylolisthesis describes the anterior or posterior displacement of a vertebra or the vertebral column in relation to the vertebrae below. It was first described in 1782 by Belgian obstetrician, Dr. Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a...
- spondylosisSpondylosisSpondylosis is a term referring to degenerative osteoarthritis of the joints between the centra of the spinal vertebrae and/or neural foraminae. If this condition occurs in the zygapophysial joints, it can be considered facet syndrome...
- Posterior Rami SyndromePosterior Rami SyndromePosterior Ramus Syndrome, also referred to as Thoracolumbar Junction Syndrome, Maigne Syndrome and Dorsal Ramus Syndrome is caused by the unexplained activation of the primary division of a posterior ramus of a spinal nerve . This nerve irritation causes referred pain in a well described...
- other degenerative spinal conditions
- any condition that causes instability of the spine
Types of spinal fusion
There are two main types of lumbar spinal fusion, which may be used in conjunction with each other:Posterolateral fusion places the bone graft between the transverse processes in the back of the spine. These vertebrae are then fixed in place with screws and/or wire through the pedicles
Pedicle of vertebral arch
The pedicles are two short, thick processes, which project dorsally, one on either side, from the superior part of the vertebral body at the junction of its posterior and lateral surfaces. They connect the body of the spinal vertebra to the arch...
of each vertebra attaching to a metal rod on each side of the vertebrae.
Interbody fusion places the bone graft between the vertebra in the area usually occupied by the intervertebral disc
Intervertebral disc
Intervertebral discs lie between adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.-Structure:...
. In preparation for the spinal fusion, the disc is removed entirely, for example in ACDF
Anterior cervical discectomy and fusion
Anterior cervical discectomy and fusion is a surgical procedure to treat nerve root or spinal cord compression by decompressing the spinal cord and nerve roots of the cervical spine in order to stabilize the corresponding vertebrae...
. A device may be placed between the vertebra to maintain spine alignment and disc height. The intervertebral device may be made from either plastic or titanium. The fusion then occurs between the endplates
Endplates
In anatomy, endplates are the parts of the vertebra that come in direct contact with the intervertebral disc to form an article . Each vertebra has two endplates: a superior and an inferior....
of the vertebrae. Using both types of fusion is known as 360-degree fusion. Fusion rates are higher with interbody fusion.
Three types of interbody fusion are:
- Anterior lumbar interbody fusion (ALIF)- the disc is accessed from an anterior abdominal incision
- Posterior lumbar interbody fusion (PLIF) - the disc is accessed from a posterior incision
- Transforaminal lumbar interbody fusion (TLIF) - the disc is accessed from a posterior incision on one side of the spine
In most cases, the fusion is augmented by a process called fixation, meaning the placement of metallic screws (pedicle screws often made from titanium), rods or plates, or cages to stabilize the vertebra to facilitate bone fusion. The fusion process typically takes 6–12 months after surgery. During this time external bracing (orthotics) may be required. External factors such as smoking, osteoporosis, certain medications, and heavy activity can prolong or even prevent the fusion process. If fusion does not occur, patients may require reoperation.
Some newer technologies are being introduced which avoid fusion and preserve spinal motion. Such procedures, such as artificial disc replacement, are being offered as alternatives to fusion, but have not yet been adopted on a widespread basis in the US. Their advantage over fusion has not been well established. Minimally invasive techniques have also been introduced to reduce complications and recovery time for lumbar spinal fusion.
Further reading
- Holmes, CF, Hershman, EB, McCance, SESean E. McCanceSean E. McCance, M.D., is an American orthopedic surgeon and Co-Director of Spine Surgery in the Leni and Peter W. May Department of Orthopaedics at the Mount Sinai Medical Center in New York City...
(May, 2005). "Chapter 9: Cervical Spine Injuries". In Schenck, RF; AAOSAmerican Academy of Orthopedic SurgeonsThe American Academy of Orthopaedic Surgeons is an orthopaedic organization.-Characteristics:Founded at Northwestern University in 1933, the AAOS has grown to include over 36,000 members. The group provides education and practice management services for orthopaedic surgeons and allied health...
. Athletic training in sports medicine. Jones & Bartlett Publishers. pp.197-218. ISBN 0892031727