The issue of cup slippage in the immediate postop period is a controversial one.
While bone ingrowth takes around 6 wks. – the hydroxy apatite to bone chemical reaction can occur much more quickly.

If we surgeons feel that the cup is not perfectly tight ( press fit)  during the surgery then we restrict activities for a 6 -8 wk period .This is done in the hope that no precipitating event would occur that would tilt the balance adversely till some stability occurs as we have not achieved primarily stability during surgery. I must say that most of these times we are able to ‘escape’ component loosening.

I have done this a few times in my very early cases , many years ago. Of course these days we get such spectacular fixation of the cup primarily that many of my patients are visiting the gym in 5-6 days following surgery.…