Patients with ankylosing spondylitis may experience spinal fractures even after minor injuries. The diagnosis of non-dislocated spinal fracture is based on clinical symptoms and radiological findings. Difficulties in interpreting the imaging studies can result in considerable diagnostic delays. We describe the steps of the radiological diagnosis in a patient with a fracture of L2 that was not visible on standard lumbar spine radiographs. Magnetic resonance imaging (MRI) T2 STIR sequences allowed determining the location and showed signs of a recent fracture. Then, MRI T1 images and computed tomography provided a detailed evaluation of the fracture line. In patients with ankylosing spondylitis, fracture instability is common, making surgical treatment mandatory. Open surgery is associated with substantial rates of infection and implant loosening. Percutaneous instrumentation has not yet been evaluated for the treatment of spinal fractures in patients with ankylosing spondylitis. This minimally invasive surgical technique enables multilevel internal fixation and may constitute an interesting alternative to open surgery.