The aim of the study is to determine if alendronic acid - the drug most commonly used in the UK as treatment of osteoporosis (thinning bones) - affects fracture healing. Participants will be randomised to receive either alendronic acid or a placebo (a tablet that contains no active drug). The main objective will be to look at the x-rays that are taken 4 weeks into the study and compare the number of healed fractures in each group (alendronic acid or placebo). We will also look at how long it takes a fracture to heal, using the x-rays taken at weeks 2, 4, 6 and 8. One person will analyse all the x-rays in the study. The x-rays will be anonymised so that the reviewer is unaware of individual details or the treatment that the participant received.