Fusion techniques for degenerative disc disease

Degenerative disc disease is part of the natural aging process of the human spine and can cause complications stemming from the nerve root or spinal cord. Degenerative disc disease of the spine can result in significant pain, instability, disturbances with the nerve roots or spinal cord, or a combination of symptoms. The cause of these symptoms comes from compression of the nerves.

When symptoms do not respond to conservative treatment, surgical treatment is considered. The goals of surgical treatment should be to remove pressure from the nerves, restore the alignment of the vertebrae and stabilize the spine. The common surgical technique to treat cervical disc disease is removal of the damaged disc with or without fusing the two adjacent vertebral bodies. Bone grafts (harvesting bone from other sites of the body) are usually used to stimulate the fusion process.

This review of 33 small studies (2267 participants) evaluated fusion techniques used to treat degenerative disc disease. The major treatments were discectomy (removal of the damaged disc) alone, addition of a fusion procedure (bone transplanted from another part of the body, cement, or cage), and addition of a plate.

None of the evidence from this systematic review indicates that one technique is better than another for clinically significant pain relief for patients with chronic cervical degenerative disc disease or disc herniation. The choice for a specific technique cannot be made on the most important aspect, pain relief, which was the primary outcome parameter in our review. There is moderate quality evidence that there was little or no difference in Odom’s criteria (a tool that measures the success of the surgery at relieving the symptoms that were troublesome prior to the surgery) between those who received a bone transplant from the hip and a metal cage to help with fusion.

There is moderate quality evidence that the use of a bone graft (bone transplanted from another part of the body) is more effective than discectomy alone in achieving fusion. There is low quality evidence that transplanting bone from the iliac crest is more effective in achieving fusion than using a cage, while cages are more effective in preventing complications.

Further research is very likely to have an important impact on the results and our confidence in them.

Authors' conclusions: 

When the working mechanism for pain relief and functional improvement is fusion of the motion segment, there is low quality evidence that iliac crest autograft appears to be the better technique. When ignoring fusion rates and looking at complication rates, a cage has a weak evidence base over iliac crest autograft, but not over discectomy alone. Future research should compare additional instrumentation such as screws, plates, and cages against discectomy with or without autograft.

Read the full abstract...

The number of surgical techniques for decompression and solid interbody fusion as treatment for cervical spondylosis has increased rapidly, but the rationale for the choice between different techniques remains unclear.


To determine which technique of anterior interbody fusion gives the best clinical and radiological outcomes in patients with single- or double-level degenerative disc disease of the cervical spine.

Search strategy: 

We searched CENTRAL (The Cochrane Library 2009, issue 1), MEDLINE (1966 to May 2009), EMBASE (1980 to May 2009), BIOSIS (2004 to May 2009), and references of selected articles.

Selection criteria: 

Randomised comparative studies that compared anterior cervical decompression and interbody fusion techniques for participants with chronic degenerative disc disease.

Data collection and analysis: 

Two review authors independently assessed risk of bias using the Cochrane Back Review Group criteria. Data on demographics, intervention details and outcome measures were extracted onto a pre-tested data extraction form.

Main results: 

Thirty-three small studies ( 2267 patients) compared different fusion techniques. The major treatments were discectomy alone, addition of an interbody fusion procedure (autograft, allograft, cement, or cage), and addition of anterior plates. Eight studies had a low risk of bias. Few studies reported on pain, therefore, at best, there was very low quality evidence of little or no difference in pain relief between the different techniques. We found moderate quality evidence for these secondary outcomes: no statistically significant difference in Odom's criteria between iliac crest autograft and a metal cage (6 studies, RR 1.11 (95% CI 0.99 to1.24)); bone graft produced more effective fusion than discectomy alone (5 studies, RR 0.22 (95% CI 0.17 to 0.48)); no statistically significant difference in complication rates between discectomy alone and iliac crest autograft (7 studies, RR 1.56 (95% CI 0.71 to 3.43)); and low quality evidence that iliac crest autograft results in better fusion than a cage (5 studies, RR 1.87 (95% CI 1.10 to 3.17)); but more complications (7 studies, RR 0.33 (95% CI 0.12 to 0.92)).