We examined the rates of necrosis of newly formed capsula tissue (the number of newly formed capsular tissues with necrosis) after the reoperation of 95 cemented and 11 uncemented total and cup endoprostheses, consisting of different arteficial joint materials. A comparison was made to the joint capsular tissue of 492 patients with arthrosis. The necrosis rate shows a lack of statistical significance within the two year-groups over a period of 12 years and between the different types of prostheses by using PMMA-bone cement. Therefore, it is assumed that a biological equivalence of the prostheses wear products is reached. It is also argued that necrosis can possibly develop from the sudden increased accumulation of PMMA-bone cement particles from the bone bed, caused by the loosening of the prosthesis. In comparison the newly formed capsular tissue of the uncemented prostheses, of which no necrosis was shown, evidence is given that the development of necrosis is chiefly due the quantity of PMMA wear products present. Because of the difficulty to exactly identify the PMMA-bone cement wear products, the toxicity of the PMMA-bone cement--who ist good known and in agreement in recent literature--or its wear products continues to be of hypothetical value in the production of necrosis. This is inspite of the successful detection by the gaschromatograph of the highly toxic paratoliudine in PMMA-bone cement. On the basis of the high statistical significance of the rate of necrosis in comparing the arthrosis joint capsules (14.83%) to the newly formed capsules (73 : 100%) it is shown that the capsulare fibrosis and scar formation to the obliteration of the lymphatic vessels is of secondary importance.

Aged↗

PubMedDate not supplied

In vivo and in vitro cellular ingrowth into a new generation of artificial ligaments.

Artificial ligaments are a useful tool in ligament reconstruction. Although the new generation of artificial ligaments shows encouraging clinical results, in contrast to earlier generations studies on the biological properties are lacking. Biopsies were taken from a ligament advancement reinforcement system (LARS) 6 months after implantation and investigated by histochemistry. An in vitro study seeding human fibroblasts or osteoblast-like cells (up to 10(6) cells for 21 days) on ligament pieces (5 x 5 mm) was conducted and analyzed by histochemistry. The biopsies showed complete cellular and connective tissue ingrowth in the LARS ligament. In vitro fibroblasts and osteoblast-like cells encapsulated the fibers by building a cellular net around them. To our knowledge, these findings demonstrate for the first time the cellular ingrowth into the LARS ligament. This mechanism might explain the strength and the inert behavior of the ligament without the synovialitis shown in clinical studies.

Adult↗