Abstract

Introduction: Cementless Total Hip Arthroplasty (THA) is a surgical procedure commonly used in the treatment of osteoarthritis of the hip. Implant manufacturers typically apply porous coatings (e.g. beads or plasma-sprayed titanium) to acetabular cup substrates to promote bone ingrowth but have recently begun to leverage additive manufacturing (AM) or “3D printing.” AM enables implant designers to create porous structures that were previously not possible, as the structures are “grown” from the substrate, not applied. The goal of this study is to compare design features and mechanical properties of AM and non-AM acetabular cups.

Methods: Two-point fatigue, static shear, static tensile, shear fatigue, plastic deformation, and particle debris tests were performed on AM and non-AM acetabular cups.

Results: Two-point fatigue endurance limits for AM and non-AM cups were 1300N and 1100N, respectively (p<0.001). There was no measurable difference in weight or debris loss for the AM and non-AM acetabular cups after 2.5 million cycles of two-point fatigue loading at 1500 N. The AM porous structure exceeded acceptance criteria in all testing - shear fatigue strength, static shear strength, static tensile strength, and plastic deformation.

Conclusion: The fatigue strength, minimal debris shedding, and stereological properties of the AM acetabular cup, along with design features exclusive to this manufacturing method may suggest that additive manufacturing can produce implants that are equivalent or superior to traditional methods. Further research is needed to assess whether additive manufacturing can lead to favorable implant stability and patient outcomes.

Keywords: Total hip arthroplasty; Acetabular component; Additive manufacturing