The disgraced studio mogul underwent what's called bilateral laminectomy surgery Thursday at an NYC hospital. We're told the procedure lasted around 3 hours. The surgery -- better known as decompression surgery -- enlarges the spinal canal to relieve pressure on the spinal cord or nerves.

As we reported ... Weinstein could barely walk on his own when he headed to court last week. He needed help from 2 handlers. He's also needed assistance from a walker. You'll recall Weinstein's lead attorney said earlier this week HW would undergo surgery while also slamming haters who accused Weinstein of attempting to play the sympathy card.