Abstract
Introduction: The Sheehan total knee endoprosthesis has been widely used since 1971. It incorporates a semi-constrained hinge with intramedullary stems cemented into the femur and tibia for fixation. This gives a stable polycentric knee mechanism that allows axial rotation as well as simulating other knee movements. This design has certain disadvantages including the large amount of bone resected for implantation and its constrained nature which predisposes to loosening. Revision rate of up to 30% have been reported. We discuss the difficulties encountered during revision and the techniques that need to be used to overcome these.
Patients and methods: We reviewed the records of 21 patients who required revision of Sheehan TKRs between 1987 and 2001. Reason for revision was recorded and all patients were scored using the Knee Society Index of Severity Instrument (Saleh et al CORR 2001). The operative details were examined and technical difficulties at the time of surgery recorded. Per-operative and early post-operative complications related to the revision procedure were also noted.
Results: The average age of patients requiring revision was 65 years old (range 39–79). The average time from primary surgery to revision was 16.2 years (range 8–20 years). The reasons for primary surgery were rheumatoid arthritis in 9 and osteoarthritis in 12. Revision surgery was required for pain associated with tibial subsidence and painful bone on bone contact in 14.Two patients had dislocation of their tibial on femoral component. One patient had a one-stage revision for infection and one had revision for a fractures tibial intramedullary stem. Three patients had revision to anterior flanged femoral components to facilitate patellar resurfacing for patello-femoral pain. The overall complication rate approached 80%!
Discussion: While the Sheehan TKR was of great benefit to a large number of patients it is not without its problems. These results show that prostheses coming to revision did not necessarily fail early and so with time we can expect more to present for revision. The high complication rate and the need for complex reconstructive techniques attest to the difficulty of revising these prostheses. Some of these problems are the legacy of the prosthetic design and should be borne in mind when taking on these cases.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
