New and Innovative Fusion Techniques

By John J. Vaughan, MD

Spinal fusion has long been used to treat a wide variety of spinal disorders. Included in this list are disorders such as fractures, deformity, and painful degenerated segments of the spine.

The first successful spinal fusions were carried out early in this century. Bone graft was harvested from one part of the body and then used to fuse the spine. At the time, there was little reliable internal fixation for the spine. Patients were therefore required to wear a cast or brace for several months to provide external immobilization while the fusion incorporated.

Over the past several decades, various forms of internal fixation devices for the spine have been developed. These include wires, rods, hooks, and screws. These implants allow corrective forces to be applied to spinal deformities while also providing immobilization so that a spinal fusion can take place.

More recently, new spinal fusion implants and techniques have been developed to hold the spine in a more reliable manner while disturbing the normal anatomy in a less invasive manner.

An example of these new techniques is minimally invasive spinal fusion techniques. In certain selected patients, anterior spinal fusions can be accomplished through minimally invasive techniques. Thoracic anterior interbody fusions can be carried out through a thoracoscope, and lumbar interbody fusions can be performed through a laparoscope. These techniques require significantly less soft tissue dissection and hence can reduce the patient's postoperative pain and lessen the recovery time.

An example of such a case is shown in Figures 1a and 1b. This patient was a 34-year-old woman with severe disabling back pain as the result of a herniated and degenerative disc at L5/S1. She underwent an anterior L5/S1 fusion laparoscopically at our institution. Through the scope, the disc was removed and two bone dowels were inserted to facilitate interbody fusion.

 

 

 

Figure 1a - Preoperative MRI scan of lumbar spine showing degenerative changes 0f L5-S1 space.

 

Figure 1b - Postoperative radiograph showing allograft bone dowels in place inserted laparoscopically

Researchers have also developed new spinal implants that facilitate spinal fusion. Lumbar fusions can not be accomplished with interbody fusion cages. These implants are hollow, threaded titanium cylinders. The cylinders contain fenestrations that allow for bone growth from one vertebra to the next. The cylinders are packed with the patient's own bone graft. Two are usually inserted at each disc level to facilitate fusion.

A case example is shown in Figures 2a and 2b. This 36-year-old man had severe chronic back pain caused by a degenerative disc at L4/L5, as demonstrated by MRI scan and discography. At our institution, the patient underwent a L4/L5 interbody fusion with interbody fusion cages.

 

 

 

Figure 2a - Anteroposterior radiograph showing threaded fusion cages in place at L4-L5.

 

Figure 2b - Lateral radiograph showing threaded fusion cages in place at L4-L5.

In summary, new and innovative spinal fusion techniques and implants are being developed. These innovations can help decrease the pain and disability associated with degenerative conditions of the spine.

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Last Updated: 10/4/03