Aims

Total knee arthroplasty (TKA) is a common and safe orthopaedic procedure. Zimmer Biomet's NexGen is the second most popular brand of implant used in the UK. The primary cause of revision after the first year is aseptic loosening. We present our experience of using this implant, with significant concerns around its performance with regards early aseptic loosening of the tibial component.

Here we present the results of functional outcome of 531 patients (aged from 27.6 to 88.7, mean 62.6) who have had the Trilogy (Zimmer; Warsaw IN, USA) acetabular shell implanted for 5 years or longer. All patients operated at our unit between 20/1/1992 and 31/3/2004 were included, looking at both Primary (431) and Revision (100) hip arthroplasties. All surgery was performed by the senior surgeon using the Trilogy shell and liners. The Trilogy acetabular shell was used with either an ultra-high molecular weight polyethylene liner or ceramic liner, along with a wide variety of femoral stems, mainly: Harris Pre-coat stem (183 patients, Zimmer), Versys cemented stem (102 pts, Zimmer), CADCAM (140 pts, Stanmore), and HAC Furlong (96 pts, JRI). There were a variety of other stems, including Exeter and Pro-femur. 48 patients had revision of socket only. Functional outcome was assessed by three questionnaires: the Oxford Hip Questionnaire (12 best function-60 worst), the Harris Hip Score (100 best to 0 worst), and the WOMAC Hip Score (0 best-96 worst). Patients filled in these questionnaires at every postoperative follow-up clinic. These were compared with the pre-operative scores obtained from questionnaires which the patients completed retrospectively. Mean follow up questionnaire times were 76.5 months postoperatively for primary arthroplasties, and 70.6 months for the revision arthroplasties. For primary arthroplasty mean scores improved from 40.8 pre-operatively to 16.4 post-operatively (Oxford), 43.9 to 92.9 (Harris), and 51.8 to 9.4 (WOMAC) (all p< 0.05). For revision arthroplasty mean scores improved from 39.1, 41.7, and 49.3 pre-operatively to 19.6, 88.0, and 12.5 (all p< 0.05). No patients required re-operation for loosening, one patient dislocated at day 5. We can conclude that the Trilogy acetabular component is a versatile acetabular implant which can be used with a wide range of femoral components, both in primary and revision Total Hip Arthroplasty, with successful functional outcome scores greater than 5 years after implantation