A buddy of mine told of how he was completely fine, until one day, walking across a busy street, he felt a stab of pain in his hip. Two weeks later he was a permanent cripple, unable to move without a cane. He had a THR. My own right hip went slowly over 3 years or so, first stiffness, then painful 'catching' when I sat, then periodic flare ups that would radiate down into my shins, then permanent shuffling about and constant pain. Had the hip done 9 months ago (ASR) and it's great. My left hip had been going slowly over the years, stiffness but no pain. Then, about a month ago, I had the exact same experience you describe, walking, perhaps striding too far, and wham, a searing pain, as the joint, I think, reached its now reduced limit. This occurs now almost daily, particularly after exercising the other hip. So I guess for me too, it's just a matter of time.