Some were left with heavy metal poisoning while others were left in constant pain.

The Federal Court has heard a UK company that manufactured a metal hip implant didn't do clinical trials before it was distributed to Australia.

Around two thousand people have joined in a class action against the UK-based company, DePuy International Ltd, which manufactured the DASR hip implants, and against the product's distributor - pharmaceutical giant Johnson & Johnson Medical Pty Limited.

In today's opening day of the hearing, which is expected to run for 16 weeks, John Sheahan QC told the Federal Court that one of their complaints is that DePuy did not conduct any clinical trials on the product.

The hearing continues.