But the 27-year-old has spoken positively of her recovery from a broken nose and sternum and collapsed lung in posting a photo of her bloodied face to social media.
Buchanan has eight world titles in BMX and mountain biking, crashing in the final of the BMX race at the 2016 Rio Olympics.
She claimed her fifth mountain bike world title in August in the four-cross discipline, a month after winning a silver medal at the BMX world championships in July.
