This paper describes investigations using the Particle Induced X-ray Emission method (PIXE) to evaluate the concentration of Ca together with that of other elements (S, Cl, and K) across the articular cartilage of domestic pigs in order to verify a putative influence of calcium on the structural changes in early arthrotic stage, derived from NMR microscopic imaging. The measurements were carried out with focused ion beams of a lateral resolution down to 20 μm. The main matrix components (C, N, O) were evaluated from proton backscattering spectra.