3D-printed titanium alloy cage in anterior and lateral lumbar interbody fusion for degenerative lumbar spine disease.

Background: The most commonly used cages for intervertebral disc replacement in lumbar fusion procedures are made predominantly from polyetheretherketone (PEEK). There is sufficient data studying their subsidence and failure rates from a variety of approaches. A novel implant is now available for commercial use, 3D-printed porous titanium (3DppTi) alloy cages, which have recently become available for use in spinal procedures. They have been shown in ovine models to have superior efficacy and fusion rates compared to traditional cages. However, there is limited data on their use in clinical practice and long-term outcomes associated with them. Methods: A retrospective chart review was performed, of all patients in a single institution who underwent lumbar spine fusion surgery via an anterior or lateral approach with a 3D-printed titanium alloy cage, between January 2020 and February 2021. Clinic letters, imaging and operation reports were independently reviewed to assess for fusion, or evidence of subsidence on follow-up. Results: Fifty patients were identified as meeting inclusion criteria, with a total of 66 operative levels. Of these operative levels, 32 were via an anterior approach and 34 via a lateral approach. One patient demonstrated a Marchi grade 0 subsidence, with recurrence of radiculopathy 2 months after an anterior approach, requiring posterior decompression and stabilization. A second patient demonstrated a Marchi grade 1 subsidence after a lateral approach, but did not require further surgery as they were asymptomatic at 2 years of follow-up. This study demonstrated an overall subsidence rate of 3.03%. There was a median follow-up time of 11.3 months for all patients. Conclusions: 3D-printed titanium alloy cages demonstrate a lower subsidence rate compared to historically published rates for alternative intervertebral cages, in anterior and lateral lumbar spine fusion surgery.