Surface adhered titanium particles on 3D printed off-the-shelf acetabular cups

3D printing is a rapidly growing manufacturing method of medical implants. In orthopedics, this method enables the construction of complex porous structures with the aim of improved bone fixation. A known by-product of the 3D printing process is surface adhered particles which are often challenging to remove from the strut surfaces of the porous region. This study investigates the presence of these particles in the porous region of unused 3D printed off-the-shelf acetabular cup from five manufacturers. Scanning Electron Microscopy (SEM) and image analysis software were used to determine the frequency and diameters of particles present on these implants. Surface adhered particles were found in the porous structures of all implants with some exhibiting more particles at the subsurface level than the surface level. Implants manufactured via Selective Laser Melting (SLM) exhibited a higher number of surface adhered particles per mm² at both the surface and subsurface levels than those manufactured by Electron Beam Melting (EBM). Additionally, and consistent with previous literature, the particle diameter of the SLM cups was found to be smaller than those on the EBM cups, as well as having a visually lower level of adherence which could raise concern about the likelihood of breakage of these particles in-vivo.