At the time, it was just a fleeting thought, a few seconds of improvisation in a studio.

Randomly slinging a jacket over her crutches, Claire Cunningham realised "that looks just like a figure". Nothing came of it at the time. But she stored the image away in the memory bank tagged: I'll get round to that one day. Maybe.

The year was 2007. Cunningam had yet to make the solo pieces – Evolution and Mobile – that have brought her widespread acclaim, and a Bank of Scotland Herald Angel award when she performed them in a double bill, ME. Now, however, that remembered image is at the forefront of the new work, Menage a Trois that she'll perform at Tramway tonight and tomorrow.

"I always had that image burned into the back of my mind – it felt as if I should make something of it," she says. "But it was only after Mobile, when I had started working so specifically with crutches, that the concept actually began to emerge. One of the last lines in Mobile is 'they're my partner'. And that said it, really. They'd become more than a mobility aid: they were what I worked with, what had given me a new career, a new artistic interest. They were, in every sense, taking me places.

"Using them on-stage, in a dance piece – talking about them, turning them into a sculpture – really altered the relationship that I'd had with crutches since I was 14. I started using them then because I'd broken my leg." (Cunningham's early-onset osteoporosis means she has brittle bones.) "I remember thinking 'I'll just be on them for six weeks.' Then six months went by. A year. And I was still thinking 'give it time' and still assuming I'd be off them sometime soon.

"But then, on-stage in Mobile, I would say how long I'd been on crutches and year on year it would change. It went from 18 to 19, then suddenly it was 20." That was when she knew it was time to make the piece that is Menage a Trois.

As with her earlier works, the source material comes from her own experiences. But if anything, this new performance peels back more profoundly personal layers than Evolution or Mobile. Those shows dealt with the physical challenges of disability, with Cunningham spinning wryly dark humour into her accounts of a childhood beset by medical procedures that sounded like medieval torture or tales of crutches that were too big, too small, too heavy, too easily broken so that the Goldilocks moments when the crutches were 'just right' rarely came. Menage a Trois goes beyond that, to where she is now because those previous shows were so successful.

She explains: "I had to confront the fact that crutches are the only partner in my life, and why is that?" The temptation was, of course, to blame work. It's what so many of us do when we lose touch with friends, or choose to stay at home with a box-set. But Cunningham wasn't in the mood to let herself off the hook.

"I knew I was using work as an excuse, and as a distraction. Yes, I was busy but I didn't need to let the work become all-consuming or get in the way of my doing other things – like having a proper social life, or significant personal relationships. And actually, by blaming work for my not having a partner meant I wasn't addressing other issues, potentially very painful issues.

"Were the crutches, the impairment, the real reason there isn't a human partner in my life? And once you've started thinking in these terms, there's no way back."

The humour took a turn for the blacker when she decided she'd use her crutches to build a man. Video-maker Gail Sneddon started sketching out ideas for a fantasy world where Cunningham could shape intense self-examination into "more of a Tim Burton kind of narrative. Something I hope speaks to a general audience".

She adds: "The risk with autobiographical work is that it turns into therapy on-stage and that's not what I want. In any case, Gail has very much been the therapist in the room throughout this process. She's gone through it all with me, became closely involved in the choreography, the dramaturgy. I don't think it would have happened without her."

She's also quick to credit the National Theatre of Scotland, and the Unlimited commission (part of London 2012's Cultural Olympiad) for support that went beyond financing Menage a Trois. "I'm still getting used to the idea that I now have a show that doesn't fit into a couple of golf bags I can sling in the car," she says.

"And it still seems strange, and amazing, that there are all these NTS people who will go off and sort stuff out for me."

Does Menage have a happy ending? "You could say that. I think facing up to issues in your life is always a good thing. And in doing just that, I've made a new piece of work but I'm determined it won't distract me from having a life as well."

Menage a Trois will be at Glasgow's Tramway tonight and tomorrow before a tour that returns to Scotland in September.