1, the clinical manifestations of osteoporosis 1.1, pain Pain is the most common and main symptom of osteoporosis, including muscle pain and bone pain. Bone pain can occur in various parts of the body, most commonly low back pain. Increased bone resorption is the initiating factor of osteoporotic pain, due to the increasing bone resorption, serious bone loss, bone trabeculae thinning, thinning, perforation or even fracture and microfracture, thinning of the bone cortex, expansion of the medullary cavity, increased intraosseous pressure, which affects microcirculation, resulting in bruising, increased periosteal stress, etc., resulting in tension pain. In the vertebral body, microfractures cause compression and deformation of the vertebral body, resulting in loss of stability of the spine and compensatory increase in muscle tension, causing muscle spasm pain. Inflammatory pain is also caused by the production of nociceptive factors such as prostaglandins after tissue injury. In addition, a number of conditions promoted or induced by osteoporosis can also cause pain. Chronic pain, swelling, dull pain and deep pain are the main causes, and acute pain can be caused by fracture. 1.2. Height loss or spinal deformation Shortening of stature and spinal deformation, mainly hunchback0, are the most common signs of primary osteoporosis. In osteoporosis, vertebral trabeculae are firstly destroyed, and the pathological changes in the number, morphology and structure of trabeculae cause a significant decrease in bone strength, and microfractures lead to vertebral compression under repeated loading. When the vertebral body is compressed, the height of the anterior middle column is reduced, while the height of the posterior functional units of the spine (vertebral plates, pedicles, spinous processes, etc.) remains unchanged, resulting in anterior flexion and retroversion of the spine and the formation of a hunchback.0 Because the bone resorption of the vertebral body is not homogeneous in osteoporosis, and because of the influence of external forces, a scoliosis deformity of the spine can also occur. 1.3. Fracture Excessive bone resorption is the essence of osteoporosis, which causes the decay of bone mass, bone structure and biological properties of bone, and in this chronic change process, the microscopic damage of bone accumulates over time, and the reconstruction and repair of bone lose the compensation and balance, which eventually makes bone strength decrease and brittleness increase, which is the pathological basis of osteoporotic fracture. Fractures are not only common in osteoporosis, but are sometimes the first cause of osteoporosis. There is a significant causal relationship between osteoporosis and fracture, as well as the fact that the majority of patients in this group are elderly, have poor vision, balance, muscle strength and concentration, and are prone to falls in daily life, which are the main external factors of osteoporotic fractures. Osteoporotic fractures are usually found in the epiphysis and the thoracic and lumbar spine. 1.4 Other manifestations Some patients have severe spinal deformity, which may cause symptoms such as chest tightness, ventilation disorders, constipation, abdominal distension, and upper abdominal discomfort. In addition, hair loss, loose and easily fractured teeth are not uncommon. 2, laboratory and other related tests 2.1, bone metabolism biochemical markers detection (1) calcium, phosphorus, magnesium level measurement: calcium, phosphorus, magnesium in the blood level is relatively stable, is an important mineral involved in bone metabolism, in the secondary osteoporosis can be increased or decreased due to the primary disease. Commonly used tests include blood calcium (total serum calcium and ionized calcium), blood phosphorus, blood magnesium and ion balance test. For convenience and accuracy, random or early morning urine calcium/creatinine ratio, urine phosphorus/creatinine ratio, and urine magnesium/creatinine ratio can also be measured. (2) Calcium-regulating hormones: parathyroid hormone, calcitonin, and dihydroxyvitamin D3 are calcium-regulating hormones that maintain the balance of calcium and phosphorus metabolism in the body. Measurement of their blood levels not only can understand the status of calcium metabolism in the body, but also has important significance for the diagnosis and identification of metabolic bone diseases such as osteoporosis. (3) Bone formation and bone resorption biochemical markers: First, the detection of bone formation and bone resorption indicators, such as blood alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP), blood osteocalcin (OC), carboxylated incomplete osteocalcin (ucOC), serum pre-collagen type I carboxy-terminal (C-terminal) pre-peptide (PICP), pre-collagen type I amino-terminal (N-terminal) pre-peptide (PINP), matrix metalloprotein. The second is the index of bone resorption, such as hydroxyproline (HOP), hydroxylysine glycoside (GHyl), antitartaric acid phosphatase (TRACP), pyridinoline and deoxypyridinoline, type I collagen N-terminal peptide (NTX) and type I collagen C-terminal peptide (CTX). With the further study of bone metabolism, a number of new biochemical markers have emerged in recent years, including osteoprotegerin (OPG), leptin and insulin growth factor-1 (IGF-1). By measuring biochemical markers of bone formation and bone resorption, we can understand the changes of bone physiological metabolism, bone mineralization, collagen degradation and synthesis in the bone matrix, and the conversion rate of bone resorption and bone formation, which is important for the early detection of metabolic bone disease and primary osteoporosis, as well as the research of therapeutic monitoring and therapeutic drugs. BMD measurement is an instrument that measures and quantifies the minerals in the bone and represents bone mass in terms of BMD, which is important for early diagnosis of osteoporosis, prediction of fracture risk, and assessment of therapeutic efficacy. However, BMD does not fully reflect the biomechanical properties of bone, fracture resistance and bone turnover, and cannot identify the cause of bone loss, and is susceptible to interference from weight and osteophytes, which may affect the assessment of bone mass and fracture prediction. Therefore, the diagnosis needs to be combined with clinical symptoms, laboratory tests and imaging examinations. Commonly used methods include dual-energy or single-energy X-ray absorptiometry, X-ray imaging absorptiometry and quantitative methods. Quantitative ultrasound can analyze bone structure, bone quality and bone strength without radiation, which is more suitable for children, pregnant women and those who are not suitable for X-ray exposure, but the scope of application is narrow. Bone strength analysis is determined by bone mineral density and bone mass. Bone strength analysis can determine the maximum external force that a particular part of the bone can withstand and is mainly used to diagnose osteoporosis and predict fracture risk. 2.5. Conventional X-ray Bone X-ray can determine osteoporosis or diagnose fracture based on bone mineral density, bone cortical thickness, bone trabecular morphology and quantity, and vertebral deformation, etc. The disadvantage is that it is only qualitative but not quantitative, and its sensitivity is poor, and it cannot diagnose osteoporosis early (30% or more bone mineral loss is required to show osteoporosis images). The basic X-ray manifestations of osteoporosis are sparse and reduced number of trabeculae in non-weight-bearing areas; increased translucency of bone; thinning of the bone cortex, enlargement of the intracortical Harvard canal and intracortical tunneling; and fractures. (1) Estimation of vertebral bone density: I degree is obvious for longitudinal trabeculae, II degree is sparse and rough surface of longitudinal trabeculae, III degree is not obvious for longitudinal trabeculae; I degree is suspicious, II and III degrees are osteoporosis. (2) Singh index: The distribution of pressure and tension trabeculae in the femoral neck was graded according to the distribution of pressure and tension trabeculae, with grade 6 being normal, grade 4 being osteoporosis, and grade 3 or less being severe osteoporosis. (3) Jhamaria grading method: According to the morphology and distribution of heel trabeculae, it is graded into 5 degrees, and below 3 degrees is osteoporosis. (4) Barnett’s cortical index method: cortical index = total cortical thickness at the midpoint of the bone / transverse diameter of the midpoint of the bone, index < 0.4 is suspected osteoporosis, < 0.35 can be diagnosed as osteoporosis. 2.6, magnetic resonance imaging Osteoporotic vertebral fractures appear as vertebral deformation on radiographs and are not easily distinguished from other causes of vertebral deformation. Although ordinary magnetic resonance imaging does not show reduced bone trabeculae or reduced bone mineral density, it can show the condition of multiple vertebral bodies, such as compression deformation of the vertebral body showing normal bone marrow signal is an old fracture, showing depressed shape, flat shape, wedge shape. In the presence of a fresh fracture, T1-weighted images may show banded or lamellar hypointense changes under the endplate of the vertebral body, but no nodular lesions. The main purpose of MRI is to make a differential diagnosis, especially to exclude tuberculosis and malignant tumors. 2.7, radionuclide bone imaging The specificity and sensitivity of this item are higher, which is convenient for dynamic observation and quantitative analysis, and is mainly used for differential diagnosis and finding some secondary causes. The diagnosis of osteoporosis depends on a thorough medical history (including current, personal, past, menstrual, reproductive and family history), physical examination, biochemical examination, quantitative BMD measurement and imaging examination. In the lumbar spine, one s is about 10%; the Z value is used to determine whether the patient's bone loss is greater than expected. For example, if a 70-year-old woman has a Z value of - 1, she is 1 s below the mean BMD value for 70-year-old women, and her T value is - 3, she is 3 s below the mean BMD value. (1) The WHO (1994) diagnostic criteria for osteoporosis in white women are based on BMD values. 1) Normal: BMD or bone mineral concentration (BMC) within +-1 s of the normal youth mean. 2) Decreased bone mass (low bone mass): BMD/BMC below normal by 1 to 2.5 s. 3) Osteoporosis: BMD/BMC below normal by 2.5 s. 4) Severe osteoporosis: BMD/BMC below normal by 2.5 s. (4) Severe osteoporosis (definitive osteoporosis): BMD/BMC below normal by more than 2.5 s, accompanied by one or more fractures. (2) The Chinese standard is the diagnostic criteria for osteoporosis in Chinese people established by the Osteoporosis Committee of the Chinese Gerontology Society in October 1999: peak bone mass (x+_ s) measured by DEXA in Han Chinese women is the standard, > – 1 s is considered normal; – 1 s to – 2 s bone mass is reduced; < - 2 s or more is osteoporosis; < - 2 s with more than one fracture is severe osteoporosis; < - 3 s or more can be diagnosed even without fracture. Severe osteoporosis can be diagnosed even if there is no fracture. If the diagnostic value is expressed as a percentage instead of s, the measured bone mineral density value is normal if it is reduced by 1%-12% compared with the peak bone mass of the same sex, reduced by 13%-24% for bone loss, reduced by 25% or more for osteoporosis, and reduced by 37% or more for severe osteoporosis.