[Interbody metal implants ("cages") for lumbar fusion]

Over the last 15 years, interbody metal implants have become commonly used worldwide for lumbar interbody fusion. The so called "cages" are made of metal or absorbable materials. By using different surgical techniques, they can be implanted either regularly or via endoscopy. The published results on surgical techniques using cages for the lumbar spine show, in most cases and with or without additional instrumentation, rates of fusion of more than 90%. It seems that the use of osteoinductive substances (especially BMP) leads to even better results. Dorsoventral fusion with internal fixation and bone show the same rate of consolidation, but the advantages of cages are primarily in the maintenance of the distraction and the possibility of a single surgical procedure without additional instrumentation (including endoscopy), and in a lower donor side morbidity.