BREAK TIME

You're at one with your mountain bike . . . and then a gum tree. "Breaks are surprisingly hard to diagnose and an X-ray really is the only sure way to tell,' says Dr Osman Bhatti. "But if you see bruising, swelling, abnormal movement and feel nauseous, a fracture is likely." Next stop, the emergency department.

BLOODY HELL

Your leg is turning a dark blue-black-ish colour. "Your bone fracture triggers tissues surrounding it to start bleeding," says Dr Ian Turnbull. "They're forming a protective clot called a haematoma where new blood vessels grow and ferry in a variety of cells to rebuild your bone."

DEAD INSIDE

"Within hours, a few millimetres of damaged bone either side of the break start to disintegrate and die," says Bhatti. "So around your fracture, there's an increase in cells called 'osteoclasts'. These eat up the dead area of bone."

ENTER THE MATRIX

Now the healing gets a bit sci-fi. "Cells called 'fibroblasts' start laying down a bone matrix," says Bhatti. That's a stiff web of calcium, cartilage and collagen. "Within eight hours, the cells under the top layer of bone and within the centre of your bone become inflamed." This is your immune system cranking up blood circulation. "Don't take anti-inflammatories like ibuprofen," advises Turnbull, "or you could stop the bone ends knitting together."

UP FOR THE CRACK

Now the good news. In 18 months, you'll be better than new. "Your healed fracture re-forms as a stronger bone than it was before the break," says Turnbull. Cut back on the booze if you want to heal quickly. It causes a loss of calcium, and your bones need this to repair. Ask for milk at the bar. Quietly.