The ankle joint offers adverse conditions to any prosthetic replacement: high loads on small surfaces, only vague landmarks for the insertion, complex and individually very different functional anatomy. Despite these obstacles many excellent short- and some long-term results have been published, giving little way to a learning curve. This contrasts with our own experiences over at all 29 years now: 24 % failures of cemented two-component EP’s after 14,6 (6,1–21,2) years (n=67) and 8,7 % failures of uncemented tri-component EP’s after 3,7 (0,6–7,6) years (n=92). We analyze and explain special problems and typical failures by a brief historical review of ankle joint replacement: as a logical sequence of various concepts, each of them basing on the knowledge of preceding insufficiencies. The general concern of the functionally useful, but limited mobility after the implantation will be discussed, also on the basis of own early and medium-term results: ROM ranging on average from 26° for TPR-(n=35) and 29° for New Jersey LCS-(n=30) up to 35° for S. T. A. R.-prostheses (n=12). Possible solutions of problems will be considered, respecting assumed causalities. Basing on the literature and own earlier investigations, especially the long-term results will be compared critically. The incertitude of an exact implantation has been partly compensated by the actual „meniscal“ concept of tricomponent prostheses. It should be favourable for their fixation to the bone and moreover reduce polyethylene-wear. But – as before – the discrepancy of high loads on a small area threatens the durability of ankle joint prostheses. Prosthetic replacement has become indispensable in the treatment of painfully destructed ankle joints, but it demands a careful and critical indication.
We evaluated histologically samples of synovial tissue from the knees of 50 patients with rheumatoid arthritis (RA). The samples were taken during revision for aseptic loosening. The findings were compared with those in 64 knees with osteoarthritis (OA) and aseptic loosening and in 18 knees with RA without loosening. The last group had been revised because of failure of the inlay or the coupling system of a constrained prosthesis. All the patients had had a total ventral synovectomy before implantation of the primary prosthesis. In all three groups a foreign-body reaction and lymphocellular infiltration were seen in more than 80% of the tissue samples. Deposits of fibrin were observed in about one-third to one-half of the knees in all groups. Typical signs of the reactivation of RA such as rheumatoid necrosis and/or proliferation of synovial stromal cells were found in 26% of knees with RA and loosening, but not in those with OA and loosening and in those with RA without loosening. Our findings show that reactivation of rheumatoid synovitis occurs after total knee replacement and may be a cofactor in aseptic loosening in patients with RA.
