If anyone had told me a year ago that I'd be a blogger I would have laughed. I am a cautious Facebook user – by turns amused and horrified at the very public way that friends (and friends of friends of friends) conduct their lives. It feels like happening upon a hidden diary and taking the wrong decision to have a quick read.

In April, I was diagnosed with a malignant giant cell tumour in my leg, and amputation was the proposed "cure". A few days before my admission to hospital, I was trying to explain to a friend how well-wishers' remarks about Heather Mills's fancy footwork on the ice rink were actually little consolation. "You should blog about it," she said. I was sceptical, not least because I didn't know what a blog was. My friend – a poet – showed me hers, and I loved the clean lines, the elegant prose, the haunting photographs. It seemed a million miles from the shouty randomness of Facebook and the cryptic soundbites of Twitter.

I thought I'd give it a go. In the days before my surgery, I wrote about my first purchase of a pair of tracksuit bottoms: "I've yet to try them on, fearing that the lure of the sofa, Jeremy Kyle and a tube of Pringles will be impossible to resist and that, if I put them on, I might never take them off."

I wrote about how it felt spending my last weekend with two legs. I didn't think I would blog from hospital but then, when my surgery was suddenly postponed, I took off my surgical gown, walked to the internet cafe and posted a blog from there. A couple of hours after I came round from the anaesthetic, I handwrote an entry which my husband delivered to my publisher to post on the site.

After that, the writing of a daily blog post became as important to my recovery as my antibiotics and physio exercises; it provided a shape to the day and gave me a sense of purpose – a sense that I had some control in an environment where almost everything else was happening to and not with me.

Without my laptop, I was forced to be inventive. Entries were written on visitors' iPhones, on scraps of paper to be taken away and typed up by my daughter, or dictated towards the end of phone calls to friends. The blog became a way for friends and family to see how I was doing, without having to ring my husband. Colleagues began to read it and to recommended it to others.

I continued to blog on my return home from hospital – sometimes just a few lines: "A Heston Blumenthal Moment. I have been trying to find a way to describe the sensation in the bit of my leg that is no longer there: Take a piece of frozen pork. While it is thawing, add a generous sprinkling of sherbet. Then poke occasionally with a sharp skewer." Other times, I mused at greater length about the nature of faith and hope; or my fear, as I watched my pile of unread novels grow, that I'd never again derive any pleasure from reading fiction.

I'm just one of many hundreds of people who blog about their illness or trauma, and, according to Dr Tom Farsides of Sussex University, this is not surprising: "Writing is an effective way of processing and coming to terms with challenging and potentially traumatic events," he says. "But blogging is more than the mere act of writing. It also fosters senses of both control and social connection, each of which is crucial for psychological wellbeing."

There does not appear to be a particular "type" of illness blogger or motivation for blogging. The style and content of every blog is as unique as the individual writer. Paul Nicholls (AKA DJ Thee Mr Mister) blogged exuberantly about his life with bowel cancer and his music right up until his death in August aged 27.

Eighteen-year-old Rosie Kilburn blogs about her life with liver cancer. She began blogging to drum up interest in her charity art auction event. " I write about anything and everything, from what I've done that day to the things that cancer makes me think about – eg death. It's not as morbid as it sounds . . . I have complete strangers following my blog, which makes me feel like someone is always listening and always caring no matter what. I've had a lot of people contact me saying they've been inspired by me and that's so great to hear because I wanted to change the attitudes of people who get cancer – survive, don't suffer."

Like Rosie, I have been touched by the interest in my blog. I occasionally check my "blog stats" and wonder how many people who log on to my blog are people who know me and how many are strangers. But I hope that, whoever my readers may be, they get even half as much pleasure from reading my blog as I do from writing it.