How long does it take for a trimalleolar fracture without surgery to heal?

6-8 weeks. Bone in a healthy person normally takes 6-8 weeks to heel. Having said that, trimalleolar fractures have the potential of being very debilitating. Along with the broken bones, you probably damaged the soft tissue between the 2 leg bones called the syndesmosis. Soft tissue can take up to 3 months to heel. Given the possible instability of this injury, surgery is sometimes the best option.