Optimized lattice gradients for hip replacement

Graded porous acetabular cage

Bone resorption for different implants  








Current hip replacement implants are made of fully solid materials which all have stiffness considerably higher than that of bone. This mechanical mismatch can cause significant bone resorption secondary to stress shielding, which can lead to serious complications such as peri-prosthetic fracture during or after revision surgery. To solve this problem, our research introduces a high strength fully porous material with tunable mechanical properties for use in hip replacement design. Our implant micro-architecture is fine-tuned to locally mimic bone tissue properties which results in minimum bone resorption secondary to stress shielding. We also present a systematic approach for the design of a 3D printed fully porous hip implant that encompasses the whole activity spectrum of implant development, from concept generation, multiscale mechanics of porous materials, material architecture tailoring, to additive manufacturing, and performance assessment via in vitro experiments in composite femurs.  These studies demonstrate the merit and the potential of tuning material architecture to achieve a substantial reduction of bone resorption secondary to stress shielding.

Relevant publications

Moussa A, Rahman S, Xu H, Tanzer M, Pasini D, Topology optimization of 3D-printed structurally porous cage for acetabular reinforcement in total hip arthroplasty, Journal of the Mechanical Behavior of Biomedical Materials, Vol. 105, 103705, 2020.

Wang Y, Arabnejad S, Tanzer M, Pasini D, Hip implant design with three-dimensional porous architecture of optimized graded density, ASME Journal of Mechanical Design, Special Issue: Design of Engineered Materials and Structures, Vol 140(11), 111406, pp. 1-13, 2018.

Arabnejad S, Johnston B, Tanzer M, Pasini D, Fully Porous 3D Printed Titanium Femoral Stem to Reduce Stress-shielding Following Total Hip Arthroplasty, Journal of Orthopaedic Research, Vol 35 (8), 1774–1783, 2017. [featured in EurekAlert, ScienceDaily, Orthopedics This Week, Endgaget, Ubergizmo, United Press International, Futurity, Breitbart, McGill Reporter, Intern Daily, Alpha Gaileo, HealthMedicinet, News-Line, MedicalExpress, Medgaget, MDT Medical Design Technology, Science & Technology World, Today’s Medical Development, Breaking news] 

Arabnejad S, Pasini D, The Fatigue Design of a Bone Preserving Hip Implant with Functionally Graded Cellular Material, ASME Journal of Medical Devices 7(2): 020908, 2013. 

Arabnejad S, Pasini D, Multiscale Design and Multiobjective Optimization of Orthopaedic Hip Implants with Functionally Graded Cellular Material, ASME Journal of Biomechanical Engineering 134(3): 031004, 2012.