Here is my two cents... and it comes after lengthy conversations with my surgeon (Dr. Pritchett), another doctor with 35 years experience in PT, and research on my own.
I experience the same sensation from very similar movements. And yes, calling it "clunking" may be the most appropriate description. But I am certain that in my case, and likely a large number of others, it has nothing to do with the prosthetic itself.
Dr. Pritchett and the PT I spoke of, believe that sensation is often generated by the sacrotuberous ligaments, slipping and snapping over the ischial tuberosity. It might help to look at an anatomy chart after reading this. The torque and twisting on the leg during surgery applies a great amount of force to the sacrotuberous ligaments. That stretches them out. In a normal person, their tension keeps them pinned to one side of the ischial tuberosity. But in people who've undergone hip trauma (note I *didn't* say "surgery") many of them describe a snapping, clicking or popping sensation.
In fact, according to the PT, he has seen it in people who've suffered a rare hip dislocation *and* in woman who had difficult births. The common culprits he believes are loose sacrotuberous ligaments snapping over the ischial tuberosity.
This is not to say clunking of BHR components does not exist. But I'd bet what many people think is just that... isn't.
In my case I know it isn't. As a test, my PT performed a series of controlled movements of my leg (on my back, non weight bearing) to replicate positions that would move the sacrotuberous ligaments into a position likely to cause snapping movement over the ischial tuberosity. Guess what??? I snapped or "clunked" every time!
BUT.... when he used his fingers (in a very awkward manner I might add) to pin the sacrotuberous ligaments to their proper position.... NO CLUNKING!
My own theory connected to all this, has to do with the repositioning of the femur after BHR surgery. In my case, the prosthetic moved the plane of my femur to a slightly more proximal position. That in turn, puts the sacrotuberous ligaments in position more likely to transverse the ischial tuberosity.
According to Dr. Pritchett, this kind of movement by those ligaments is not problematic and unlikely to cause pain. It's weird yes. But I'm hoping in time as those ligaments continue to shrink to pre-op position... the "clunking" will shrink too.