Chapter 28 Osteoporosis Presentation: 2005 谢瑞满Rui-man Xie，Ph.D., M.D. Professor of Neurology & Gerontology ZhongShan Hospital, Fudan University rmxie@zshospital.net, xieruiman@yahoo.com Objective 1、Definition 、types and mechanism of osteoporosis  2 、Diagnosis 、prevention and treatment of osteoporosis  3 、Etiology and Epidemiology of osteoporosis times –45 minutes ×2 Overview Definition : Osteoporosis is a bone disease in which the amount of bone is decreased and the structural integrity of trabecular bone is impaired. Cortical bone becomes more porous and thinner. This makes the bone weaker and more likely to fracture. figures Associated changes in body shape and vertebra （deleted 6 pictures ）Patients with risk factors or conditions that cause osteoporosis Postmenopausal woman with family history of hip fractures or kyphosis Medications: corticosteroids, dilantin, gonadotropin releasing hormone agonists, loop diuretics, methotrexate, thyroid, heparin, cyclosporin, depot-medroxyprogesterone acetate Hereditary skeletal diseases: osteogenesis imperfecta, rickets, hypophosphatasia Endocrine and metabolic: hypogonadism, hyperparathyroidism, hyperthyroidism, Cushing syndrome, acidosis, Gaucher's disease Marrow diseases: myeloma, mastocytosis, thalassemia Others: Anorexia, Malabsorption, Cystic fibrosis, Renal insufficiency, Hypercalciuria, Hepatic disease, Depression, Spinal cord injury, Systemic Lupus, Weight below healthy range, Cigarette smoking Epidemiology The population of older men and women has been increasing, and therefore the number of people with osteoporosis is increasing. In the USA, about 21% of postmenopausal women have osteoporosis (low bone density), and about 16% have had a fracture. In women older than 80, about 40% have experienced a fracture of the hip, vertebra, arm, or pelvis. Women have more osteoporotic fractures than men. Age is one of the most important risks in all groups. The decreased physical activity may be playing a role in increased hip fractures. Mechanism : Bone physiology The bone is continuously remodelling, and the bone surface moves in and out. The Basic Multicellular Unit (BMU) is a wandering team of cells that dissolves an area of the bone surface and then fills it with new bone. The sequence is Origination, Osteoclast recruitment, Resorption, Osteoblast recruitment, Osteoid formation, Mineralization, Mineral maturation, Quiescence. Bone strength (Quality): In addition to bone porosity, the bone strength is determined by the trabecular microstructure. Perforations of individual trabecula occur when resorption cavities are too deep. This, too, is seen with estrogen deficiency. The remaining trabecula are not as well connected and are mechanically weaker. Mechanism : Bone physiology Microfracture healing is another aspect of bone strength that is not measured by bone density. Trabeculae inside the bone may fracture and microcalluses are formed that resemble the calluses seen on xrays of long bones after a "macro-fracture". Osteoporotic bone is more susceptible to these fractures because the individual trabeculae do not have as many reinforcing connections. The calluses may represent a method of repairing the bone and even connecting some of the trabecula. Bone which has lost the ability to form these calluses will be weaker. The age of the bone mineral crystals may also play a role in the strength of bone. This is an area that needs further research. Studies suggest that older bone is more brittle, and that one purpose of bone remodelling is to remove the old bone and replace it with newer, more elastic bone. Clinical manifestation and types Secondary osteoporosis ：Mndocrine and metabolic: hypogonadism, hyperparathyroidism, hyperthyroidism, Cushing syndrome, acidosis, Gaucher's disease; Marrow diseases: myeloma, mastocytosis, thalassemia; Medications: corticosteroids, dilantin, gonadotropin releasing hormone agonists, loop diuretics, methotrexate, thyroid, heparin, cyclosporin, depot-medroxyprogesterone acetate; Malabsorption 、Hepatic disease, others ；Hereditary skeletal diseases: osteogenesis imperfecta, rickets, hypophosphatasia; Primary osteoporosis. Clinical manifestation and types Primary osteoporosis ：TypeⅠpostmenopausal osteoroposis ——This is seen with estrogen deficiency. There is high bone turnover rate. The proportion of trochanteric and femoral neck fractures increases；Type Ⅱelderly osteoroposis ——This is aging in bone physiology. The compression fracture of the spine and hip fracture are more common. Clinical Features of Osteoroposis The vast majority of hip fractures occur after a fall. About 5% appear to be “spontaneous”fractures, in which the patient feels a fracture and then falls. Overall about half of hip fractures are intertrochanteric and the others are femoral neck fractures. Clinical Features of Osteoroposis Vertebral compression fractures vary in degree from mild wedges to complete compression. The symptoms also vary, but the degree of compression is not necessarily related to the amount of pain. In fact, about 60% of women with compression fractures do not realize they have had a fracture! It is possible that some of the fractures occurred gradually and therefore did not cause acute pain. Clinical Features of Osteoroposis When women and men do suffer painful compression fractures, the pain usually lasts from one to two months, is localized to the back with accompanying muscle spasms, then gradually subsides. Patients with continuing severe pain should be evaluated for other pathologic etiologies of the fracture, especially malignancy or myeloma. Persistent pain can also be caused by continuing fracture, muscle spasms, spinal stenosis, or degenerative joint disease. Clinical Features of Osteoroposis To correctly interpret a spine xray, it is important to know the definition of a vertebral fracture, which is not quite as straightforward as it first appears, especially for research. For practical clinical purposes, a vertebra can be considered fractured if the anterior height is 80% or less of the posterior height. A new fracture requires loss of at least 20% of anterior or posterior height. Clinical Features of Osteoroposis Wrist fractures are more common in women who are 50 to 60 years old. These are caused by falls or other trauma. Osteoporosis does not appear to impair the healing of the wrist fractures, and they cause only short-term disability. Although spine, hip, and wrist fractures are considered classical osteoporotic fractures, many others are related to bone density and thus are also osteoporotic. These include rib, pelvic and shoulder fractures, but not finger, facial bone, skull, elbow, or ankle fractures. Clinical Features of Osteoroposis The irreversible height loss associated with osteoporosis is one of the aspects of the disease that is most distressing to many women. Height loss can also occur with scoliosis, which often gets worse after menopause. Also, degenerative disk disease can cause height loss of 2 inches. Some reversible height loss is due to poor posture. KYPHOSIS is the feature of osteoporosis that is identified by most patients. The hump causes difficulty in finding clothes that will fit, let alone look attractive. In severe cases, the ribs contact the iliac crest and movement causes pain. Clinical Features of Osteoroposis PROTRUDING ABDOMEN The protruding abdomen which is a result of the kyphosis is an unrecognized aspect of osteoporosis. Women do not realize that the curvature of the spine decreases the abdominal space, and thus the intestines have nowhere to go except forwards. Many women think that they are getting fat, and they go on a diet trying to regain their youthful waistline. If they do successfully lose weight, it will only increase their risk for more osteoporotic fractures. Clinical Features of Osteoroposis DECREASED PULMONARY CAPACITY Patients with kyphosis have decreased lung volumes. In severe cases this leads to shortness of breath and pulmonary symptoms of restrictive lung disease. Clinical Features of Osteoroposis REFLUX ESOPHAGITIS Patients with kyphosis may develop reflux esophagitis due to the