Abstract
Introduction: Concerns of backside wear have made the use of the all polyethylene tibial component a viable choice in primary total knee arthroplasty. This study compares the results of two groups, one with a modular tibial component and one with an all polyethylene tibial component.
Materials: Between 1986 and 1995, 670 patients underwent total knee arthroplasty using one design with a PCL retaining prosthesis. 500 patients in this group were implanted with a modular tibial component and 170 an all polyethylene tibial tray. The groups were comparable in sex and age (74.1 years for the metal trays and 75.8 years for the all polyethylene components.). The average follow up is 83.9 months for the metal tray group and 74.8 months for the all poly tibial group. The arthroplasties were evaluated annually using the Knee Society guidelines.
Results: The postoperative Knee Society Score were 74.5 (metal) and 73.9 (all polyethylene). Joint specific scores for the all polyethylene were slightly higher at 89.9 compared to 88.5 for the metal tray group. Revision rates were 1.8% (3 cases in the polyethylene group) and .8% for the metal group (8 cases). The 3 revisions in the all polyethylene group were for late infections while 5 of the 8 in the metal group demonstrated polyethylene wear/osteolysis.
Discussion and conclusions: The clinical results of the all polyethylene group are equal the modular tibial tray group. Because of the excellent radiographic results and non-existent mechanical failure rate to date, the all polyethylene group also provides an opportunity to reduce wear debris with subsequent osteolysis.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
