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Show ••/ELtJWSJ V COLLEGE OF ENGINEERING UNDERGRADUATE RESEARCH A TRACT Anthony Chyr Bart Raeymaekers 1 8 IMPROVING HIP IMPLANT DURABILITY BY MEANTS OF MICRO-TEXTURED SURFACES Anthony Chyr (Bart Raeymaekers) Department of Mechanical Engineering University of Utah More than 200,000 total hip replacement (THR) surgeries are performed in the US each year. Presently, the statistical survivorship of these implants declines dramatically after 10 years of use [1 ]. This lack of durability has unacceptable effects, such as riskier revision surgery [2,3] or surgery postponement with its attendant pain and disability, which are rooted in the same cause: wear. Even short term wear can cause inflammatory reaction, tissue necrosis, osteolysis, and instability caused by wear debris [4]. This research focuses on the metal-on-polyethylene (MOP) bearing type, which is most commonly used in the US. The current engineering paradigm for femoral head design is to manufacture ever smoother surfaces. This research aims to break this paradigm and attempts to achieve hydrodynamic lubrication in M O P hips using surface microtexturing. Our results suggest that with the microtexture, hydrodynamic lubrication is established earlier in the gait cycle, at a lower sliding speed, and thus is maintained over a larger portion of the reciprocating sliding cycle. This first prototype texture design demonstrates that reducing M O P hip wear using a microtextured femoral head is indeed feasible. Femoral component Tibial insert U) mmmme<:, »- -, Surface roughness Synovial fluid \ Texture Pelvis Detail of the articulating surface o the femoral head Acetabular component Texture on femoral head Stem Femur J) "I ^ < ™ w. \ CoCr cylinder Synovial JIUKI n [1] American Academy of Orthopaedic Surgeons (http://orthoinfo.aaos.org/topic.cfm?topic=a00389) [2] S. Kurtz, F. Mowat, K. Ong, N. Chan, E. Lau, M. Halpern, "Prevalence of primary and revision total hip and knee arthroplasty in the United States from 1990 through 2002," J. Bone Joint. Surg. Am. 87:1487-1497 (2005) [3] K. Ong, E. Lau, J. Suggs, S. Kurtz, M. Manley, "Risk of subsequent revision after primary and revision total joint arthroplasty,"Clin. Orthop. Rel. Res. 468:3070-3076 (2010) [4] JJ. Jacobs, N J. Hallab, R.M. Urban, M.A. Wimmer, "Wear particles," J. Bone Joint Surg. Am. 88:99 (2006) |