567 - Assessing Laser Fabrication Technology on PEEK Implants: Medical Devic...

#567 Assessing Laser Fabrication Technology on PEEK Implants: Medical Device Wear Testing; Profilometry

Cutting Edge Innovations/Non-conventional Therapies

Poster Presented by: T.M. Ganey

Author(s):

H. Hoskin (1)
L. Ferrara (2)
L. Detter-Hoskin (3)
E. Woods (3)
F.E. Livingston (4)
T.M. Ganey (5)

(1) Weslyan School, Norcross, GA, United States
(2) OrthoKinetic Technologies, LLC, Southport, NC, United States
(3) Georgia Institute of Technology, Atlanta, GA, United States
(4) Aerospace Corporation, El Segundo, CA, United States
(5) Atlanta Medical Center, Orthopaedic Surgery, Atlanta, GA, United States

Abstract

Purpose of the Study: Orthopaedic literature abounds with descriptive assessments that value surface chemistry and its potential to achieve enhanced bone cell attachment. A recent advance in laser technology was used to define a surface mimetic that mirrors isotropic bone. In vitro cell culture analysis suggests that the surface treatment enhances the deposition of matrix and preferentially encourages the attachment of bone cells. Before submitting to in vitro analysis, this study sought to determine whether repetitive loading changes the surface topography of a laser-etched PEEK implant, and in the context of any potential changes, whether any particles exuded can be calibrated according to standard procedures for medical device wear testing.

Materials and Methods: Three implants was subjected to 3 million cycles of repetitive loading at 5 Hz. Loading forces of 600N, and 800N were applied for 3 million cycles to two of the devices and the third served as a control. Once prepared, the samples were analyzed using CCSEM (computer-controlled scanning electron microscopy) to determine the size distribution of the particles. The CCSEM analyses were performed using the backscattered electron imaging mode to allow for the detection of all desired particulate species within the population. During the analysis, particles were individually detected based on electron signal above background. Once detected, each particle was measured, and its elemental constituents were identified. Size and morphological characteristics, as well as associated elemental constituents, were recorded on a particle-by-particle basis. Profilometry was used to contrast and measure the surface topology at a sub-micron threshold.

Results: Gross examination did not reveal significant differences in the appearance of the devices after the loading cycles. Particle analysis revealed that 95% of the particles were less than 5-micron in diameter and that the yield of the implant to the wetting solution was significantly less than the allowable percentage of material shedding established as 4 mg in rabbit, and 56 mg in humans. Results from 600N - .403mg at 1M, .627 mg at 2M; 800N - .639mg at 1M; .225 mg at 2M.

Profilometry analysis demonstrated that the impact of testing did not grossly change the macro-geometric structure of the implant but did offer a new scale of relative heights contrasted after etching. With the resolution of the non-contact imaging, differences in micron depth of the channels were noted, but given the lack of particles that were counted, it was clear that the etching process produced a material that was cohesive with regard to shear shedding and at the same time compliant to some loading consistent with its material properties.

Conclusion: Based on standard particle analysis and non-contact profilometry, manufacturing with laser technology appears to offer a useful and novel means for fabrication of materials surfaces requiring controlled patterns and integrated topology.