Abstract
Introduction Revision total knee arthroplasty is becoming a more frequent procedure throughout Europe. Painful patello-femoral problems, patellar dislocation, impingement pain as well as aseptic loosening and gross malalignment are among many causes. We investigated the routine use of CT scans in identifying alignment causes for failure as well as in the pre operative planning of the procedure.
Method Twenty poorly functioning total knee arthroplasties were analysed using the Perth CT protocol. All patients were awaiting revision total knee arthroplasty and were scanned using a GE multislice CT scanner. The measurements were performed using standard CT software.
Results The mean coronal position of the components was 3 degrees of valgus for the femoral component and 2.5 degrees of varus for the tibial component. Fourteen knees had errors of femoral component rotation, which ranged from 1 degree of external rotation to 9 degrees of internal rotation. Nine knees had errors of tibial base-plate rotation with all being internally rotated relative to the PCL/Tibial tuberosity axis from 3 to 12 degrees.
The cumulative error of implantation ranged from 6- 24 degrees in all 7 planes.
Discussion Revision total knee arthroplasty remains a difficult procedure but is increasing in frequency. The use of a CT protocol allows all coronal, sagittal and rotational errors in previous implantation to be accurately identified prior to surgery. We believe that all knee revision operations should have a CT scan as part of the pre operative planning.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
