Evolution of materials for implants in metastatic spine disease till date – Have we found an ideal material?. (October 2021)

• Record Type: Journal Article
• Authors: Kumar, Naresh; Lopez, Keith Gerard; Alathur Ramakrishnan, Sridharan; Hallinan, James Thomas Patrick Decourcy; Fuh, Jerry Ying Hsi; Pandita, Naveen; Madhu, Sirisha; Kumar, Aravind; Benneker, Lorin M.; Vellayappan, Balamurugan A.
• Is Part Of: Radiotherapy and oncology. Volume 163(2021)
• Page Start: 93
• Page End: 104
• Publication Date: 2021-10
• Subjects: Spine -- Neoplasm metastasis -- Implants -- Ti6Al4V -- Polyether ether ketone -- Carbon fiber -- Medical imaging -- Radiation oncology; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2021.08.007
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: Evolution of stainless steel and Ti6Al4V implants in spine surgery. Adaptation of Ti6Al4V implants to metastatic spine tumor surgery (MSTS) Emergence of polyether ether ketone (PEEK) for use in MSTS. Ideal implant material for MSTS should be imaging & radiotherapy compatible. We also highlight necessary ideal characteristics of implant material for MSTS. Abstract: "Metastatic Spine Disease" (MSD) often requires surgical intervention and instrumentation with spinal implants. Ti6Al4V is widely used in metastatic spine tumor surgery (MSTS) and is the current implant material of choice due to improved biocompatibility, mechanical properties, and compatibility with imaging modalities compared to stainless steel. However, it is still not the ideal implant material due to the following issues. Ti6Al4V implants cause stress-shielding as their Young's modulus (110 gigapascal [GPa]) is higher than cortical bone (17–21 GPa). Ti6Al4V also generates artifacts on CT and MRI, which interfere with the process of postoperative radiotherapy (RT), including treatment planning and delivery. Similarly, charged particle therapy is hindered in the presence of Ti6Al4V. In addition, artifacts on CT and MRI may result in delayed recognition of tumor recurrence and postoperative complications. In comparison, polyether-ether-ketone (PEEK) is a promising alternative. PEEK has a low Young's modulus (3.6 GPa), which results in optimal load-sharing and produces minimal artifacts on imaging with less hinderance on postoperative RT. However, PEEK is bioinert and unable to provide sufficient stability in the immediate postoperative period. This issue may possibly be mitigated by combining PEEK with other materials to form composites or through surface modification, although further research is required in these areas. With the increasing incidence of MSD, it is an opportune time for the development of spinal implants that possess all the ideal material properties for use in MSTS. Our review will explore whether there is a current ideal implant material, available alternatives and whether these require further investigation.