Joint replacement is a logical step in the treatment of severe joint pathologies with irreversible lesions resisting conservative therapy. At the spinal level, arthrodesis became, very early, the gold standard of treatment for severe intervertebral disc pathologies. The next logical step was to envision functional replacement, and this step was taken as early as 1956, when the first intervertebral implant was described. However, it took many more years and a great variety of proposed implant designs before clinical applications could be attempted.

Spinal arthrodesis is a generally accepted procedure for the management of patients with a variety of spinal disor- ders. The primary goal for spinal fusion is to eliminate the instability of the spine, often caused by trauma, deformity, tumor, inflammation or infection, and common degenera- tive deterioration of the motion segments. In many clini- FRA paw', cal situations, the optimal solution in restoring the spine's integrity is through surgical intervention. There are many techniques of spinal fusion applicable to the lumbar spine. Posterior (PLIF) and anterior lumbar interbody fusion...