[Bone and boundary zone changes following the implantation of double-cup arthroplasties].

21 femoral heads of 20 patients with double cup arthroplasty were examined after an implantation period of 1 to 5 years, in one case after 18 years. In 8 cases the hipe socket and in 10 cases the femoral cup became loose. Therefore an operative removal was necessary. 2 patients showed extensive periarticular ossifications. In connection with the metal cup the resected femoral heads were cut in slices of 1 cm. thickness. After taking an X-ray they were embedded without decalcification in methylmetacrylate. The sections were stained with different methods (Goldner, v. Kossa modification). In the group with fixed cup a local osteoporosis is dominating. The fibrous tissue membrane between cement and bone tissue is varying in thickness. It is thicker at the periphery of the cup. In the group with loosened cups large irreparable bone necrosis with included histiocytic granulomas, could be observed. The clinical problems are discussed in accordance to the long term prognosis on the basis of the morphological results.