a method for repairing a defect in cartilage , comprising the provision of apertures in the cartilage by drilling holes at the base of the cartilage defect , which holes may enter the mesenchymal depot , introducing a porous scaffold material containing a plurality of magnetic particles into the apertures , and subsequently and sequentially injecting magnetically - tagged cartilage growth promoting materials such as various growth factors or chondrocytes into the area of the defect . the magnetically tagged growth promoting material is then drawn into the apertures by magnetic attraction of the magnetic particles contained in the porous scaffold material , either by virtue of the particles being permanently magnetic , or by the imposition of an external magnetic field . the present application claims the biodegradable porous scaffold material containing the plurality of magnetic particles .