When joints become inflamed all of the suppoorting muscles in the vicinity of that joint become tense and loose their effectiveness at the full length of movement.

The groin muscles or adductors are typically shortened by an inflamed hip joint and this is not very good for rehabilitation of the joint because by shortening it working area you are actually causeing the joint to work in a smaller area of the socket and actually increasing wear on the affected area.

Doing the groin stretch will ensure that the joint is working over a greater area and also stops these muscles becoming locked and inactive.