To answer this question - it depends upon any restrictions such as don't bend past 90 degrees which will make a difference to this 1. if you have restrictions, then you cannot/should not try sleeping on your side until these have expired. Maybe 6, 8 or even 12 weeks - it depends upon the surgeon. 2. if you don't have restrictions, you can attempt it at about 4 weeks. However, there are problems with this. 1. when a person lays on their back, their legs tend to roll inwards (internal rotation) which increases the risk of dislocation - like this 2. getting onto and off your back, increases that risk even further, hence the urge to be cautious about this. A secondary "however"! You can pre-empt this by getting a long pillow and placing it down your back, operated side up, thereby rolling ever so slightly onto the non-operated side. But do have another ordinary pillow - not too fat - between your legs to stop the upper leg rolling inwards - similar to this However, this is only going to be for a few weeks, 6 at most, so please think twice before you start spending silly money on these special pillows. Much the same can be achieved by ordinary pillows and/or rolled up blankets or duvets.