Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Introduction:The growing incidence of spinal conditions requiring surgical intervensions prompted innovations in implants and instrumentation. However, the selection of the right implant material is critical due to the unique mechanics of the spine. Specifically, spinal implants necessitate exceptional properties such as biocompatibility, superelasticity, strength, and fatigue resistance, which can be present in NiTinol shape memory smart implants. The precise design of NiTinol implants remains challenging. 3D printing has emerged as a promising solution to customize implants according to individual medical requirements, considering appropriate material properties. 

 Purpose: Our goal is to evaluate the current use of shape memory NiTinol in orthopedic and spinal surgery and explore its future potential in clinical applications. Additionally, we aim to investigate the opportunities and challenges of 3D printing NiTinol "smart" components for biomedical implants, covering aspects such as biocompatibility, clinical applications, and insights from existing literature. This centralized information will serve as a valuable resource for surgeons and engineers.

 Methods: The review comprehensively investigates 3D printed NiTinol implants, analyzing literature from 2000 to the present (11/2023) with search terms 'NiTinol alloys for spine implants' and '3D printed NiTinol alloys for spine implants'. Utilizing tools like 'Origin Pro' we were able represent the research literature through graphical presentation.  

Results:Significant advancements have been achieved in NiTinol biomedical implants, encompassing NiTinol Staples, Interbody Fusion Cages, Rods, and Expandable Pedicle Screws. These developments ensure both biocompatibility and safety. Notably, the use of NiTinol rods has facilitated minimally invasive techniques, allowing for compact delivery and subsequent expansion upon placement. From Origin Pro analysis, the NiTinol and 3D printed NiTinol implants comprise a relatively low proporsion of medical implants accounting for just slightly above 4.5% of all the types of medical implants (Figure a&b).

Discussion:

This review illuminates the potential and challenges associated with utilizing 3D printing for NiTinol smart components in biomedical implants (figure a&b). It consolidates existing knowledge, underscoring the significance of these implants for medical practitioners and researchers. However, the need for further in vivo studies to assess the long-term systemic effects of these 'smart' implants across diverse patient groups is emphasized. The 3D printed NiTinol 'smart' biomedical implants play a crucial role in addressing gaps in various aspects of NiTinol implants, particularly in terms of biocompatibility and clinical applications. Serving as a valuable resource, this review centralizes essential information for both surgeons and engineers.

Conclusions:

The use of 3D-printed NiTinol implants in spinal surgery shows promise, with modified variations exhibiting positive outcomes. However, comprehensive in vivo studies are essential for a thorough understanding of the long-term effects across diverse patient groups. Despite these advancements, further research is needed to identify and enhance implant materials to meet evolving requirements for spinal instrumentation.

Figure : Literature survey based on the search terms shown in the figures compared various alloys, including NiTinol, Titanium, Stainless Steel, and PEEK, for (a) different alloys used as spine implants in comparison with (d) 3D printed alloys used in spine implants.