First Results of a New Vacuum Plasma Sprayed (VPS) Titanium-Coated Carbon/PEEK Composite Cage for Lumbar Interbody Fusion.

The aim of this study was to assess the performance of a new vacuum plasma sprayed (VPS) titanium-coated carbon/polyetheretherketone (PEEK) cage under first use clinical conditions. Forty-two patients who underwent a one or two segment transforaminal lumbar interbody fusion (TLIF) procedure with a new Ca/PEEK composite cage between 2012 and 2016 were retrospectively identified by an electronic patient chart review. Fusion rates (using X-ray), patient's satisfaction, and complications were followed up for two years. A total of 90.4% of the patients were pain-free and satisfied after a follow up (FU) period of 29.1 ± 9 (range 24-39) months. A mean increase of 3° in segmental lordosis in the early period ( = 0.002) returned to preoperative levels at final follow-ups. According to the Bridwell classification, the mean 24-month G1 fusion rate was calculated as 93.6% and the G2 as 6.4%. No radiolucency around the cage (G3) or clear pseudarthrosis could be seen (G4). In conclusion, biological properties of the inert, hydrophobic surface, which is the main disadvantage of PEEK, can be improved with VPS titanium coating, so that the carbon/PEEK composite cage, which has great advantages in respect of biomechanical properties, can be used safely in TLIF surgery. High fusion rates, good clinical outcome, and low implant-related complication rates without the need to use rhBMP or additional iliac bone graft can be achieved

Basic concepts in metal work failure after metastatic spine tumour surgery.

PURPOSE The development of spinal implants marks a watershed in the evolution of metastatic spine tumour surgery (MSTS), which has evolved from standalone decompressive laminectomy to instrumented stabilization and decompression with reconstruction when necessary. Fusion may not be feasible after MSTS due to poor quality of graft host bed along with adjunct chemotherapy and/or radiotherapy postoperatively. With an increase in the survival of patients with spinal tumours, there is a probability of an increase in the rate of implant failure. This review aims to help establish a clear understanding of implants/constructs used in MSTS and to highlight the fundamental biomechanics of implant/construct failures. METHODS Published literature on implant failure after spine surgery and MSTS has been reviewed. The evolution of spinal implants and their role in MSTS has been briefly described. The review defines implant/construct failures using radiological parameters that are practical, feasible, and derived from historical descriptions. We have discussed common modes of implant/construct failure after MSTS to allow further understanding, interception, and prevention of catastrophic failure. RESULTS Implant failure rates in MSTS are in the range of 2-8%. Variability in patterns of failure has been observed based on anatomical region and the type of constructs used. Patients with construct/implant failures may or may not be symptomatic and present either as early ( 3months). It has been noted that not all the implant failures after MSTS result in revisions. CONCLUSION Based on the observed radiological criteria and clinical presentations, we have proposed a clinico-radiological classification for implant/construct failure after MSTS