Radiographic assessment of anterior titanium mesh cages

Carbon fiber and titanium cage implantation for anterior column support dur ing spinal fusions is an alternative to the use of more traditional structu ral allografts and autografts. The authors report instrumentation and cage failure for patients who underwent spinal fusion with structural titanium m esh cages implanted into the anterior column a minimum of 2 years after sur gery. They wanted to determine whether plain radiographic techniques can be used to critically assess disk space and corpectomy fusions after implanta tion of these radioopaque cages. Fifty patients having undergone spinal fus ions using structural titanium mesh cages in the anterior column had 99 ant erior levels fused with at least 1 (maximum of 2) titanium mesh cage, resul ting in a total of 131 cages used. The cages were examined for evidence of settling, migration, or failure. The anterior and posterior instrumentation was assessed for evidence of failure, and the spine was examined for evide nce of successful fusion. Radiographic cage settling (>2 mm) into the verte bral body end plates was observed, but cage migration or failure were not. An average lordotic correction of 10 degrees was observed, with loss of cor rection into kyphosis from immediately after operation to final follow-up a veraging 2 degrees. As an average of all reviewers, using a strict radiogra phic fusion assessment, definite or probable anterior fusion was graded at 81% of the levels, probably not or no at 5% of the levels, and could not be assessed at 14% of the levels. Definite or probable posterior fusion as an average of all reviewers was graded at 44% of the posterior fusion levels, questionable at 4%, no at 5%, and could not be assessed at 47%. The use of anterior-only, posterior-only, or anterior and posterior instrumentation w ith structural titanium mesh cages in the anterior spine along with proper autogenous bone grafting techniques provided anterior column support with a low rate of radiographic complications. Acceptable anterior spinal fusion rates, as assessed by a consensus agreement of reviewers, were observed pri marily by evaluation of the fusion mass around the cages (extracage fusion) , because intracage fusion was difficult to assess.