Osteoporosis is defined as a skeletal disease characterised by compromised bone strength predisposing a person to an increased risk of fracture. The consequences of these fractures include pain, disability, depression, loss of independence and increased mortality. Bone mineral density (BMD) correlates well with the fracture risk with the relative risk of fracture approximately doubling for every standard deviation decrease in BMD. Dual energy X Ray absorptiometry (DEXA) is the method used to diagnose osteoporosis according to criteria established by world health organization. The WHO defines osteoporosis as a bone density that falls 2.5 standard deviations below the mean for young healthy adults of the same sex – also referred to as a T score of -2.5.
Postmenopausal women who fall at the lower end of the young normal range (a T score < -1.0) are defined as having low bone density and are at increased risk of osteoporosis. Apart from advanced age, small stature, family history and female sex, current cigarette smoking, early menopause or bilateral ovariectomy, alcoholism, inadequate physical activities are other risk factors for osteoporotic fractures.
Management of Osteoporosis
The goal of treatment is to prevent fractures and manage pain especially low back pain due to osteoporosis. Lifestyle interventions for osteoporosis include regular weight bearing exercise and avoidance of unhealthy behaviour such as cigarette smoking and excess alcohol intake. The medications that are used for the management of osteoporosis may be divided into those that prevent bone resorption (estrogen, alendronate, risedronate and calcitonin) or other anabolic agents such as teriparatide. Estrogen is not used as drug of first choice because of associated risk of breast cancer, stroke and venous thromboembolism. The bisphosphonates alendronate and risedronate are both proven to reduce the risk of hip fractures and may be good choices in elderly patients at high risk of hip fractures. Calcitonin and raloxifene are useful agents where reduction of hip fracture risk is not the primary concern and calcitonin may have an analgesic effect in patients with acute painful vertebral fractures. Teriparatide, human recombinant parathyroid hormone is approved for use in women and men at high risk of fracture. It is taken in the form of subcutaneous injections taken daily for a period ranging from 6 months to 2 years.
The osteoporotic compression fractures of spine can be managed by interventions such as vertebroplasty or kyphoplasty. While percutaneous vertebroplasty involves placing bone cement through a needle placed through the skin, balloon kyphoplasty involves inflating a balloon within the vertebral body before bone cement is placed in the created space. The other indications where vertebroplasty is effective is osteolytic bone lesions, myelomas, hemangiomas and osteoporosis. Cement leakage is a potential complication of vertebroplasty which is seen less often with kyphoplasty.