Novel biomaterials have a great deal of appeal for usage in spinal deformity surgery. Can bioresorbable implants replace metallic implants for a variety of applications in the spine? Will a non-PMMA bone cement give the same results for vertebroplasty and/or kyphoplasty as that seen with PMMA? These two articles only begin to answer these questions.
While it appears that bioresorbable interbody spacers are effective in facilitating fusion in the presence of iliac crest autograft, it remains to be determined (except for the imaging benefits) whether or not this technology is an improvement compared with existing techniques in achieving interbody fusion. Also, the development of implants that are exposed to shear and tensile stresses (such as plates, rods and screws) has not yet had extensive preclinical, much less clinical testing. Based on animal and early clinical trials, these materials appear to be safe for use in the spine, but that is the limit of our current knowledge regarding this particular biomaterial. Nevertheless, the concept of the premeditated disappearance of an implanted foreign body is quite attractive.
The material properties of PMMA and the heat generated by polymerization process of this material are thought by some to be disadvantages to this substance as a biomaterial. PMMA, however, is inexpensive, readily available, and has a proven track record for a variety of indications. Also, some think that the exothermic reaction may play a role in pain relief after vertebroplasty and kyphoplasty. Nevertheless, the concept of greater biocompatibility and bioactivity is very attractive for the treatment of a variety of skeletal disorders, including osteoporotic fractures and spinal deformities. Osteointegration has the potential for reduction of long-term morbidity (i.e., loosening) compared with PMMA.
Overall, the use of novel biomaterials in spinal surgery is in its infancy and its future appears to be promising. Extensive basic science research, animal studies, and clinical trials will be needed. The results of these further studies will be exciting to follow.