The following three cases highlight the potential serious consequences of trampolining. Case 1: Lisfranc fractureA 27-year-old woman with good past health was admitted with left foot pain and swelling in July 2014. She fell with axial loading on an inverted and plantar-flexed left foot while trampolining. Physical examination showed bruising on the dorsum of her left foot with tenderness over the base of the first and second metatarsals. Range of movement was limited by pain. Subsequent X-ray showed widening of the Lisfranc joint with base avulsion (Fig a). Lisfranc fracture was diagnosed. Open reduction with screw and K-wire fixation were performed and a resting ankle-foot orthosis was given. On follow-up 2 weeks after surgery, sensation and circulation in the toes were good. Range of movement was still limited by pain, however. She was encouraged to move her ankle and toes, and to mobilise with heel-walking at 6 weeks postoperatively. Case 2: vertebral fractureA 25-year-old swimming instructor with good past CASE REPORT