Abstract
Introdution:
Over the last years research has focused on attempts to achieve better fixation in knee prosthesis by improving cementing techniques and prosthetic designs; thus prosthetic fixation is critical while loosening at the bone-cement interface is still an important matter for the orthopaedic surgeon.
Material and Method:
In the present study, we evaluated in vivo displacement of both total and unicompartimental knee prosthesis implanted on 73 patients by collecting data from RSA associated to the conventional X-rays and clinical follow-ups; we were able to reach only 18 patients (2 males and 16 females) for the actual follow up because of death or other diseases occurred on the other patients over the years (mean age at the time of surgery 68, range 27–83).
Results:
As shown in Fig 1 there is an evident increase of MPTM during time and this is an effect of the implant wear. Comparing this trend with a early stability MPTM, after a stabilization of the implant during the first 2 years, we can define a plateau of normal working and after it a degenerative curve. Fig 2 shows the trend of the patient as KSS score. It is evident the pre- to post- operative increase of the curves. After it there is a valley during the normal activity, that is not evident as MPTM modification and then a trend of degeneration starting from 8–10 years of follow-up.
Conclusions:
Our study highlighted the trend of a prosthesis during all of is life. The RSA device guarantees a very good image quality and the implant life curves became very accurate. Further studies are going to better characterize that curves and correlation between migration and clinical scores at long term follow up.
