Twenties. ballet/athlete. left hip dysplasia becoming increasingly problematical. shouldn't this have been solved as a baby?

Depends: While hip dysphasia occurs as a child, the future ramifications may last and worsen into adulthood. This depends entirely on whether the hip joint maintained normal shape and thus developed properly or not. If there is residual deformity, it will likely lead to future pain and arthritis. You should have an xray evaluation to find this out.