gms | German Medical Science

Objective: The material of the intervertebral cages and especially their characteristics concerning biocompatibility, imaging artifacts in xray, CT and MRI and bony integration is an ongoing matter of discussion. This study evaluates new sintered titanium cages that seem to combine the most beneficial properties of available cages and materials.

Method: 20 consecutive patients who underwent MIS TLIF due to instability or degenerative disease between 01/2013 and 01/2014 were included. 27 cages made of trabecular sintered titanium (T-Maxx / Sharxx, Maxxspine) were implanted and combined with transpedicular screw/rod fixation in all cases. All underwent xray intraoperatively, direct and 6 weeks post surgery as well as xray and CT after one year. 5 patients had postoperative MRI. Artifacts in postoperative imaging, subsidence and bony integration with fusion were evaluated during a follow-up of at least 12 months.

Results: The visibility of the cages showed to be optimal in xray, as the contour of the cages was clearly delineable in all patients without obscuring the surrounding bony structures. In the CT scans the surrounding bone especially the fusion mass was easy detectable. Fusion could be clearly visualized in 25 of the 27 implanted levels (92%) after 1 year. In the 5 patients which had undergone postoperative MRI, no relevant artifact could be detected as long as spin echo sequences were performed. A susceptibility artifact of less than 2 mm could be measured around the cages. All relevant information concerning the spinal canal, the nerve roots in the foramen and the vertebral body could be obtained from the images.

Conclusions: In contrast to peek cages, which are thought to cause defined lytic zones in the surrounding bone, the new sintered titanium cages combine the advantageous biocompatibility of titanium implants resulting in a high fusion rate with optimized imaging properties including a clear direct visibility in xray images. In contrast to solid titanium and tantalum cages CT images did not show the typical blurring artifacts but allowed a detailed evaluation of the surrounding structures including the fusion mass in and around the cages. In MRI, only minor susceptibility artifacts occurred allowing a good assessment of the spinal canal, the nerve roots in the foramen and the vertebral body. It could be shown that cages made of sintered titanium combine the most beneficial properties regarding material and imaging and thus can be used for the benefit of patients.