Comparison between Titanium and Polymer Interbody Cages in Spinal Fusion Surgery: A Review of Clinical Studies

In recent years, spinal fusion surgery has become one of the most common treatments for spinal cord injuries, while the interbody cages, which replace the damaged interbody discs in the surgeries, have undergone extensive changes in design and material. These changes are quite visible, ranging from plain titanium cages made using the conventional manufacturing methods to customized porous titanium cages, which are made using additive manufacturing technology, or titanium-coated polymer cages. Among all the materials used in manufacturing the interbody cages, PolyEther Ether Ketone (PEEK) and titanium are the most common ones. Each of these two has its own advantages and disadvantages. Several studies have compared these two materials, mostly based on the two characteristics of subsidence and fusion rates. The present study performed a comprehensive review of the published clinical studies comparing the titanium and PEEK cages in order to make a comprehensive evaluation of these two. According to the reviewed studies, both materials had relatively similar results in subsidence rate, with no significant difference. However, it was shown that the titanium cages had a better fusion rate and subsequently were more likely to be successful in the clinical settings than the PEEK cages.