Long-term results of the Blauth knee prosthesis - Current status of hinged knee prostheses

Aim: Currently there is widespread use of unconstrained knee arthroplasty even in severe deformities of the knee. In order to ascertain the value and future of constrained knee prostheses, we have assessed the results of the Blauth knee prosthesis and compared them with the results of unconstrained knee prostheses. Methods: In a retrospective analysis we examined 227 Blauth knee prosthesis implantations performed between 1985 and 1997. Using endpoints of prosthesis removal, infection and aseptic loosening, the 10-year survivorship analysis was evaluated. Results: The analysis shows a 10-year survivorship of 90.1% using aseptic loosening or infection as an endpoint and 96.2% using removal as an endpoint. Conclusion: The first designs of constrained knee prostheses were associated with a high failure rate, while more recent designs like the St. Georg knee prosthesis and the Blauth knee prosthesis show long-term results similar to condylar designs. Since there has been a large increase of knee endoprosthesies implantations in the last years, a constrained knee prosthesis with excellent long-term results remains a valuable implant in cases of revisions and difficult knee arthroplasty.