OUTCOME AFTER THRUST PLATE PROSTHESES FOR OSTEOARTHRITIS IN HIP: A FOLLOW UP OF UP TO FIFTEEN YEARS

Thrust plate prosthesis (TPP) is a bone conserving prosthesis in use for over thirty years. TPP is a stemless and uncemented femoral prosthesis fixed at the lateral femoral cortex with a bolt, plate and screw. This has a metal-on-metal articulation with a 28mm Metasul head and Allofit press fit acetabular cup. Our study aimed to assess the survival of this prosthesis. At Oswestry 234 TTP9s were implanted between 1995 and 2005. All patients completed a self-assessed questionnaire of Harris Hip Score pre-operatively and post-operatively at 2 months, 1 year, and then yearly. Only those who had a follow up was within the last two years were included in the analysis. 76 patients who had failed to satisfy the criteria were excluded. Of the 158 hips in the study 75 hips were in male patients and 83 were in female patients. The median age of patients was 52 years (range 15 to 82). 75 hips were on the right side and 83 on the left. All patients were operated by the senior author or a senior trainee under his supervision (seven hips). Revision of the implant or decision to revise was taken as the end point of our study. The median time to follow up was 7 years (range 1 to 15). The median pre-operative hip score was 43 (range 3 to 77) which rose to 83 points (range 11 to 100) at the latest follow up. Median hip score in females improved from 39 to 82 points and in males from 52 to 85 points. Twelve patients (5.1%) underwent revision surgery either for infection or aseptic loosening. The Thrust Plate Prosthesis had a good outcome with an increase in hip score of 40 points and 94.9 % survival at a median of 7 years.