Wear of ultra-high molecular weight polyethylene manufactured with laser powder bed fusion

dc.contributor.authorMosco, Morgan Elizabethen
dc.contributor.committeechairRaeymaekers, Barten
dc.contributor.committeememberWilliams, Christopher Bryanten
dc.contributor.committeememberNowinski, Matthew Clarkeen
dc.contributor.departmentMechanical Engineeringen
dc.date.accessioned2025-06-06T08:01:47Zen
dc.date.available2025-06-06T08:01:47Zen
dc.date.issued2025-06-05en
dc.description.abstractMore than 750,000 total knee replacement (TKR) surgeries are performed annually in the United States (US) to treat degenerative joint diseases such as osteoarthritis. A prosthetic knee implant typically comprises a cobalt chromium (CoCr) femoral component and a polyethylene tibial insert that is constrained in a tibial tray. The articulation between the femoral component and tibial insert replaces the function of the natural knee joint. Advances in design, manufacturing, and materials have increased the statistical survivorship of prosthetic knee implants. However, despite extending the longevity of prosthetic knee implants, approximately 20% to 40% of patients are unsatisfied with their TKR. The advent of image processing and additive manufacturing (AM) technologies has raised interest in personalized prosthetic (knee) implants. Such patient-specific implants could potentially improve patient outcomes and satisfaction by improving knee kinematics compared to a standard implant, which improves functionality, and by enabling an almost perfect anatomical fit and improved positioning of the implant, which reduces stress-shielding and promotes bone ingrowth, thus reducing potential complications. However, AM of the polyethylene tibial insert has not yet been achieved, yet it is crucial to implement patient-specific implants because it defines the knee kinematics. The low melting point of ultra-high molecular weight polyethylene (UHMWPE) and the entanglement of long polymer molecules prevents use of extrusion-based AM techniques such as fused filament fabrication (FFF). Hence, in this work, we use laser-powder bed fusion (L-PBF) to manufacture UHMWPE specimens. We print and post-process cylindrical pin specimens and perform pin-on-disc wear testing against stainless steel countersurfaces. We measure wear as a function of sliding distance for 3D-printed UHMWPE specimens of different density and compare the results to those of conventionally extruded and machined UHMWPE specimens. The results demonstrate that the wear rate of 3D-printed UHMWPE specimens decreases with increasing density and ultimately approaches that of extruded UHMWPE specimens. The results of this work are relevant in the context of 3D printing patient-specific knee implants to improve clinical outcomes for patients.en
dc.description.abstractgeneralEvery year, more than 750,000 people in the United States undergo knee replacement surgery to relieve pain and restore movement caused by conditions like osteoarthritis. These surgeries involve inserting a metal and plastic implant that mimics the function of a natural knee. While advances in technology have made these implants last longer, up to 40% of patients are still not fully satisfied with the results. To improve outcomes, researchers are exploring personalized knee implants that are custom-designed to better match each patient's anatomy. These personalized implants could improve joint movement and reduce complications by better fitting the patient's anatomy. However, making custom components—especially the plastic part of the implant that interacts with the metal part—has been challenging using current 3D printing methods. This study investigates a new way to 3D print a type of plastic called ultra-high molecular weight polyethylene (UHMWPE), which is commonly used in knee implants. Using a technique called laser powder bed fusion, the researchers successfully printed and tested plastic samples to measure how well they resist wear and tear. They found that as the printed material became denser, its performance improved and closely matched that of traditionally manufactured plastic. These findings bring us one step closer to being able to create fully customized knee implants using 3D printing, which could lead to better outcomes and higher satisfaction for patients in the future.en
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:43632en
dc.identifier.urihttps://hdl.handle.net/10919/135087en
dc.language.isoenen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectultra-high molecular weight polyethyleneen
dc.subjectlaser powder bed fusionen
dc.subjectwearen
dc.subjectdensityen
dc.titleWear of ultra-high molecular weight polyethylene manufactured with laser powder bed fusionen
dc.typeThesisen
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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