Spondylarthropathies (SpA) are associated with an increased risk of clinical and radiographic vertebral fractures (VF). This has most extensively been documented in ankylosing spondylitis (AS). Two types of VF have been described in AS. Firstly, classical VFs can occur in the thoracic and lumbar vertebral bodies. Secondly, once multilevel ankylosis of the spine has occurred, fractures then can occur also in other parts and directions of the vertebrae and in the cervical spine. VFs with wedging of the vertebral bodies contribute to hyperkyphosis and vertebral body and other VFs, especially when occurring in the ankylosed spine, can result in luxation and instability and in - sometimes severe - neurological complications, even after a minor trauma.
Fracture prevention consists of a 5-step plan including case finding strategies to identify subjects at risk of fractures, risk evaluation, differential diagnosis, therapy and follow up.
Case finding: Most non-vertebral fractures are easily diagnosed. However, the diagnosis of a VF is often a challenge, even more so in AS. Indeed, back pain is a classical feature of AS, and is usually attributed to inflammation. As long as a VF is not part of the differential diagnosis of back pain, VFs will be overlooked. Imaging of the thoracic and lumbar spine is the only method to diagnose VFs of the vertebral bodies, and can be performed using classical X-rays or by vertebral fracture assessment using DXA. The diagnosis of other VFs can be difficult on classical X-rays and is therefore often delayed. MRI, CT and bone scintigraphy can be helpful for diagnosis in the ankylosed spine.
Risk evaluation: Imaging of the spine is indicated in AS patients with clinical suspicion of a VF and in patients with risk factors for fractures. Clinical risk factors for fractures can be evaluated by using the FRAX and Garvan fracture risk algorithms. VF in AS occur more often in men then in women. BMD should be measured in the spine and hip, as a normal BMD of the spine has to be interpreted with caution in the presence of syndesmophytes and squaring of the vertebrae: in spite of increased DXA-BMD in the spine, a high mSASS is associated with VFs. High disease activity, inflammatory bowel disease (IBD) and psoriasis are risk factors for low BMD and VF, and disease duration for VFs, but VF have already been found in some patients with early SpA.
Differential diagnosis: In patients with SpA with a VF and in patients who require medical treatment to prevent fractures, medical history and clinical and laboratory examinations allow to diagnose or exclude previously unknown contributors to secondary osteoporosis and metabolic bone diseases, and malabsorption in the case of IBD. Vitamin D deficiency is endemic, and is also documented in AS patients.
Treatment at the time of diagnosis of a VF: AS patients with a VF with neurological complications often need specialized surgery, especially in the ankylosed spine, and such fractures are often followed by incomplete clinical recovery. In the absence of neurological complications, as is the case of uncomplicated vertebral body fractures, pain can be treated with analgesics. NSAIDs delay fracture healing and temporarily stopping NSAIDs should be considered at the time of a fracture.
Fracture prevention: Patients with a multilevel ankylosed spine should be advised to avoid trauma and to consider imaging of the spine in case of increased or persistent back pain, even after a minor trauma. Calcium intake should be optimized and vitamin D supplements are indicated in case of vitamin D deficiency. Anti-resorptive medications (bisphosphonates, denosumab) are indicated in the presence of a VF, low BMD and/or in the presence of multiple other risk factors.
Follow up: Medical treatment should be monitored for tolerance and compliance. In case of suspicion of a first or new VF during treatment, imaging of the spine is indicated and the images should be compared to baseline images. In case of new fractures during treatment, teriparatide and PTH should be considered. After 3-5 year therapy with bisphosphonates, a full re-evaluation of the fracture risk is advocated, in order to decide about a drug holiday in case of low fracture risk or continuation of therapy in case of persisting high fracture risk.
Disclosure of Interest None Declared