In a mechanically stable situation (ligament transposition), the material allows capillary vessels to grow into the prosthesis, but it does neither induce the formation of a "neo-ligament" by dody-own tissue nor an interweaving of the nascent parallel collagenic fibres with one another. No direct contact between polyethylene and bone is built at the fixation points. Apparently this material is not suitable for being used as tendon substitute, and its applicability as a ligament substitute is limited because the mechanical properties which are acceptable until 500 days after the implantation are lost after this period and a good tolerance can only be achieved under certain, most restricted conditions.