An increasing number of patients suffer from hip joint degeneration. One possible treatment is hip replacement surgery, during which an artificial ball-and-socket joint substitutes the damaged natural one. In detail, the ball-shaped head of the femoral bone is removed and replaced by an implant. One potential problem associated with implants that are too strong is stress shielding, i.e., the reduction of stresses that act on the remaining natural bone. The reduced stresses can result in bone resorption, which, in turn, can cause implant loosening. To counteract stress shielding, implant designs that are inspired by porous bone are proposed [1]. In particular, the designs comprise lattice structures, which can additionally facilitate bone in-growth and can be produced by additive manufacturing. Numerical analysis of such implants comprising lattices can predict their performances and eventually even enable their numerical design. Both require geometric models of the implants, which, following the approach of tiling [2], can be generated by composing splines. The generated models are not only suitable for a direct isogeometric analysis, but the approach also enables local optimization of the lattice structures [3]. The presentation will apply the workflow to an exemplary scanned bone geometry. [1] P. Müller, A. Synek, T. Stauß, C. Steinnagel, T. Ehlers, P.C. Gembarski, D. Pahr, R. Lachmayer, Development of a density-based topology optimization of homogenized lattice structures for individualized hip endoprostheses and validation using micro-FE. Scientific Reports (2024) 14:5719. [2] G. Elber, Precise construction of micro-structures and porous geometry via functional composition. Mathematical Methods for Curves and Surfaces (2017) 108–125. [3] J. Zwar, G. Elber and S. Elgeti, Shape optimization for temperature regulation in extrusion dies using microstructures. Journal of Mechanical Design (2023) 145(1):012004.