Bioresorbable cage for interbody fusion Progress in research and clinical application / 中国组织工程研究

ABSTRACT

BACKGROUND: The use of interbody cages is rapidly increasing in filed of spinal fusion surgery. The inherent limitations of conventional cages such as cage migration or failure, radiopacity, fusion stress shielding, late-onset inflammation and osteolysis give some impetus for the development of bioresorbable cages. Compared with conventional cages, they show better rigidity and elasticity coefficient, with less interference on the imaging evaluation. OBJECTIVE: To introduce the materials classification and property, animal studies, clinical application, current drawbacks and future directions of bioresorbable fusion cages, and provide objective evidences for the research and clinical application of the cages.RETRIEVAL STRATEGY The relevant articles published between December 1990 and December 2006 were searched for in Pubmed database by the researchers of this article, with the key words "bioresorbable cages, spine, SCI" in English. A total of 550 articles were selected and reviewed preliminarily by the inclusive standards of research about materials, animal studies and clinical application of bioresorbable cages. Exclusion criteria repetitive studies.LITERATURE EVALUATION The main sources of literatures are researches about materials, animal studies and clinical application of bioresorbable cages. Among the 27 selected articles, 1 is review, while others are clinical or elementary experimental studies. DATA SYNTHESIS: ①Materials Polylactides becomes the most useful and applied base material for bioresorbable spinal interbody cages; characteristics of bioresorbable materials include crystallinity, average molecular weight, molecular weight distribution (polydispersity), and glass transition temperature. There are also several points to consider in the design of bioresorbable cages such as characters related to degradation, functional degradation rate, intensity of inflammatory response and occupation by other tissues following degradation.②Animal studies Quadruped can be a valuable model for the study of the spine, but it has its limitations; Researches in vitro are focused on these cages of their degradation characters and maintenance of the spinal elasticity; Researches in vivo consisted of the characters of biomechanics, degradation, fusion and foreign body reactions of these cages.③Clinical application Bioresorbable cages are satisfactory for the clinical application in the TLIF, PLIF of lumbar operation and the ACDF of cervical operation in short term follow up study.④Bioresorbable cages have their drawbacks, which may bring about the development of related techniques.CONCLUSION:The research and application of bioresorbable cages are at the preliminary stage, but the results that we have got are promising for their further research and clinical application.