The Blues centre-back was involved in a collision with Jamie Mackie and stretchered from the St Andrews pitch half-an-hour into the 1-1 draw at St Andrews and rushed straight to hospital.
After the match Blues boss Alex McLeish told BRMB Radio that, as was suspected, reports from the hospital had confirmed that Ridgewell had broken a bone in his leg and a shin bone too and so will obviously miss Blues' final three games of the season.