Kim,
It might be biofilm. However, one would expect if an infection was present in those areas biofilm would be too and vice versa.
As an classically trained osteopath I start thinking about musculoskeletal imbalances in those areas from years of faulty mechanics that lead to hip degeneration, and then the stress of putting in a replacement. If infection has been ruled out, and inflammation doesn’t appear to be obvious I would look for other causes and have these people see practitioners who can provide some body work, i.e. cranial osteopath, chiropractor, orthotics.
Dr. Woeller