The natural course of radionuclide bone scanning in the evaluation of total knee replacement--a 2 year prospective study.

In order to establish the natural course of radionuclide bone scanning images after total knee replacement 41 consecutive patients were scheduled for examination 3, 7, 12 and 24 months after surgery. The mean age was 69 years (range 50-80 years); the female:male ratio was 4:1. Thirty-two patients completed the entire program. A total of 143 99Tcm medronic acid complex scintigrams was performed. No significant difference between the grades of total scintigraphic uptake at any of the four examinations nor any difference between the first and the last examinations could be demonstrated (P = 0.58, Friedman test and P = 0.20, Wilcoxon test, respectively). Twelve months after surgery one fifth of the knees still demonstrated definitely increased scintigraphic uptake and 24 months after surgery 12.5% of the knees had definitely increased uptake. We believe that the increased uptake seen for a variable length of time after surgery limits the usefulness of radionuclide bone scanning in the evaluation of total knee replacement.