Lord D opened up about the aftermath of his accident on Thursday's episode of "The Kardashians" as Khloé Kardashian took him to see a doctor for his back pain -- something he attributes to his Lamborghini rollover wreck last year near Calabasas.

The back pain isn't all Scott says he's still dealing with ... he also says the accident led to some weight gain and all of it is directly affecting his sex life.

When the doc asks Scott what he'd usually do for fun before the crash, he says sex but admits he's terrible at it now, thanks to a lack of mobility. Khloé's no doctor, but she's got some sorta bedside manner ... because she asks Scott if he'll be motivated to fix his pain so he can "get back on the wagon to f**k?"

Scott even jokingly suggests maybe once he's all healed up, he and Khloé could test out his new back in the sack! Not surprisingly ... Kourtney's sis refused to participate in that joke!

TMZ broke the story, Scott's accident was a scary one ... but thankfully, no one else was involved in the accident. Outwardly, he walked away with just a minor cut to his head, but obviously, there was more internal damage.