Stable migration of peri-apatite-coated uncemented tibial components in a multicentre study

Aims Hydroxyapatite coatings for uncemented fixation in total knee arthroplasty can theoretically provide a long-lasting biological interface with the host bone. The objective of this study was to test this hypothesis with propriety hydroxyapatite, peri-apatite, coated tibial components using component migration measured with radiostereometric analysis over two years as an indicator of long-term fixation. Patients and Methods A total of 29 patients at two centres received uncemented PA-coated tibial components and were followed for two years with radiostereometric analysis exams to quantify the migration of the component. Results While there was significant variation in individual migration patterns, the overall migration of the tibial component in the study group demonstrated a pattern of initial migration followed by stabilisation after one year, with mean maximum total point motion (MTPM) of 0.02 mm (standard deviation (SD) 0.20) between one and two years post-operatively. The direction of greatest motion was subsidence, which stabilised at three months post-operatively (mean translation of 0.21 mm, SD 0.40). Conclusion The tibial component migration pattern of stabilisation in the second post-operative year is indicative of successful long-term fixation for this PA-coated tibial component.