Study design: A literature review was conducted of basic science research and clinical experiences describing the use of interbody cage devices for the management of degenerative spinal abnormalities.
Objectives: To summarize current knowledge regarding the use of interbody fusion cages.
Summary of background data: Degenerative conditions of the lumbar and cervical spine are a major societal expense and a leading cause of disability. Fusion surgery may be used to treat patients with some of these conditions. During the past decade, interbody cages have been popularized as a useful fusion technique with high rates of clinical and radiographic success reported. Cages may be implanted using a variety of surgical approaches to the disc space and can be used alone or with supplemental posterior fixation.
Methods: A literature review of biomechanical, biologic, and clinical studies of threaded interbody cages was performed.
Results: Interbody cages have been shown to successfully promote fusion in a variety of animal models. In biomechanical studies, anteriorly placed threaded cages significantly stabilize the motion segment in all directions except extension. Posteriorly placed cages provide less stability as a result of the facetectomy required for placement of an appropriately sized device. Successful clinical and radiographic results have been reported with the use of interbody cages. Most reported cage failures are the result of technical difficulties with implantation or poor patient selection. Accurate radiographic assessment of fusion in the presence of a metal interbody cage remains challenging, and studies evaluating alternate biomaterial cages are underway.
Conclusion: Interbody cages are a useful technique for achieving spinal fusion and have been shown to have an acceptable clinical success rate in appropriately selected patients.