How to apply a cast for forearm fractures
The forearm bones (radius and ulna) are the two most commonly broken bones in the body.1 Immediate management of these injuries includes applying a plaster cast—called a back slab—to the dorsal aspect of the forearm. These casts are a simple and effective way of providing temporary stabilisation of the fracture and pain relief. All medical students and junior doctors should know how to apply a dorsal back slab.2 It is usually applied in the emergency department or orthopaedic theatre, but it might also be required during expeditions or in remote settings on elective placement.
The back slab bridges the gap in treatment until definite fracture fixation takes place—that is, an operation is planned within a few days or a full circumferential cast is applied once swelling has settled. In both cases, a fracture of a forearm bone will take about six weeks to heal.
It is important that a