World osteoporosis month

Osteoporosis:

Interventions to manage vertebral fractures

Dr (Maj) Pankaj N Surange

MBBS, MD, FIP

Interventional pain and spine specialist

Some important facts about osteoporosis

·        Osteoporosis is a systemic skeletal disorder characterized by low bone mass, disruption of the microarchitecture of bone tissue, and compromised bone strength which leads to an increased risk for fracture.

·        Bone strength is a product of both bone density and bone quality. Bone density is expressed as grams of mineral per area or volume; bone quality refers to factors such as architecture, turnover, damage accumulation (e.g., microfractures), and mineralization

·        Osteoporosis is common among menopausal women but is often clinically silent until a fragility fracture occurs. Osteoporosis is also being recognized with increasing frequency in older men.

·        After peak bone mass is reached, the bone remodeling process is in a state of equilibrium until menopause. Cessation of estrogen production leads to rapid bone loss of approximately 2% to 3% per year in the spine for up to 6 to 8 years, which accounts for 50% of the total spinal bone loss among normal women .This is then followed by a slower rate of bone loss (0.5%/year), which is attributed to aging.

·        Even among men, it is now known that estrogen deficiency plays a big role in bone loss, perhaps an even bigger role than played by testosterone . Studies among osteoporotic males have shown a closer correlation between estradiol levels and bone mineral density (BMD) than testosterone and BMD. A finding that men with osteoporosis may have low estradiol yet normal testosterone levels further supported this correlation.

·        Clinically, osteoporosis is diagnosed when bone mineral density (BMD) is reduced or when fragility fractures (ie, fractures after little or no trauma) occur. Dual-energy x-ray absorptiometry (DXA) is by far the best standardized technique and is preferred for diagnosing osteoporosis and monitoring responses to therapy. BMD assessment by DXA has been used by the World Health Organization to define osteopenia and osteoporosis

·                    The most common misuse of the WHO criteria is applying it to nonwhite postmenopausal populations. The fracture risk/T-score relationship used for these criteria was derived solely from a database of white, postmenopausal women. Thus, the criteria cannot be taken to mean or suggest the same fracture risk when the individual being measured is male, premenopausal, or nonwhite.

·                    The T-scores obtained from peripheral sites do not have the same fracture implication as those obtained with central machines.

·                    Degenerative changes in the spine are exceedingly common among the elderly. These are seen as sclerotic changes in the facets and discs as well as osteophyte formation. They elevate BMD and may lead to falsely normal BMD and T-scores in the spine.

·                    Vertebrae with compression fractures are denser than normal vertebrae and would have higher T-scores. It would be a big mistake to withhold therapy for a patient who appears to have normal T-scores due to compression fractures.

The most common osteoporosis-related fractures involve the thoracic and lumbar spine, the hip, and the distal radius.

Biochemical evaluation

Successful management of osteoporosis requires a careful choice of biochemical tests to determine the presence of secondary causes of osteoporosis. At a minimum, laboratory evaluation should include a complete blood cell count, serum chemistry panel, liver function tests, and serum thyroid-stimulating hormone and calcium determinations.

Complete Blood Count

Complete blood count (CBC) tests can detect anemia, which can be seen in many secondary causes of osteoporosis; these include celiac sprue and other malabsorptive states, chronic liver disease, chronic kidney failure, metastatic bone disease, and multiple myeloma.

KFT

Renal insufficiency often leads to a deficiency in 1–25 OH vitamin D deficiency and secondary hyperparathyroidism, which must be addressed prior to initiation of osteoporosis therapy. Bisphosphonates are contraindicated when GFR falls below 30 mg/24 hours

Liver Function Tests

An alanine aminotransferase (ALT) test is the most cost-effective way to screen for liver disease among osteoporotic patients. Elevated ALT levels suggest liver dysfunction, which, regardless of the cause, increases the risk of vitamin D deficiency.

Serum calcium

Postmenopausal women as a group are commonly affected by primary hyperparathyroidism .A serum calcium determination adequately screens for this disorder

Treatment of osteoporosis

The essentials of management for most forms of osteoporosis include the following:

• Lifestyle modifications.
• Nutritional interventions.
• Pharmacologic therapies.
• Interventional procedures for vertebral fractures

Lifestyle Modifications

Safety of the patient's immediate environment to prevent falls and fractures, eliminating habits that are deleterious to skeletal integrity and that can contribute to falls

Discontinue smoking and alcohol consumption.

Weight-bearing exercise program

In patients with inflammatory diseases who are receiving long-term glucocorticoid therapy and are at risk for osteoporosis, an exercise and physical therapy program is imperative

Nutritional Interventions

Nutritional interventions for osteoporosis should assure that the diet plus supplements provide at least 1200 mg of elemental calcium per day and up to 1500 mg in high-risk patients over the age of 70 with established disease or with steroid-induced osteoporosis.

Pharmacologic Therapy

Drugs for osteoporosis can be divided into two major classes: antiresorptive and anabolic agents. Antiresorptive agents inhibit bone resorption, mainly through their action on osteoclasts, whereas anabolic agents stimulate osteoblastic differentiation and activity.

Antiresorptive Therapy

Bisphosphonates

These pyrophosphate analogues bind to hydroxyapatite crystals in the bone, are taken up by osteoclasts in the bone, and exert their action by inhibiting the mevalonate pathway, subsequently leading to inhibition of osteoclast function and increase in rates of apoptosis. Oral bioavailability is generally low, only 1% to 3%, and is greatly inhibited by food, calcium, iron supplements, and drinks. Patients must be advised to take this medication in the morning, to withhold food and drinks to ensure good absorption, and to remain upright for at least 30 minutes.

Raloxifene

Raloxifene is a selective estrogen receptor modulator, with agonistic effects on bone. The major efficacy trial for raloxifene was the Multiple Outcomes of Raloxifene Evaluation (MORE) Trial. The LS BMD increase over the 3-year study period was 2% to 3%, and vertebral fracture reduction rates in women with and without preexisting fractures were 50% and 30%, respectively.

Calcitonin

Because of its modest effect on BMD, and small fracture risk reduction, calcitonin is rarely used as first-line therapy; rather, owing to its mild analgesic effects, this drug is more commonly used now as an adjunctive therapy after an acute vertebral fracture, usually combined with a stronger antiresorptive.

Hormone Replacement Therapy

Hormone replacement therapy (HRT) was the original antiresorptive therapy used for osteoporosis. However, current controversies centered on increased breast cancer, and cardiovascular risks have resulted in a marked decline in use for osteoporosis indications.

Anabolic Therapy

Teriparatide

Synthetic human parathyroid hormone [PTH (1–34)], or teriparatide, is an anabolic agent that has been approved for postmenopausal and male osteoporosis treatment

Combination Therapy

Trials that have studied combination therapy for osteoporosis had BMD and not fracture risk reduction as the primary endpoint. Thus, although the effects appear to be additive, it is unknown whether there is indeed a greater reduction in fracture risk when two agents are combined.

Interventional procedures for vertebral fractures

Kyphophasty and Vertebroplasty

These two surgical modalities have been reported to successfully relieve pain from acute compression fractures and decrease kyphosis slightly .The procedures entail injection of polymethylmethacralate or bone cement directly into the fractured vertebra in vertebroplasty, and into a balloon within the vertebra, in kyphoplasty.

 Vertebroplasty is a percutaneous procedure with a low complication rate that provides immediate and long-¬term pain relief to patients suffering from chronic ver¬tebral compression fracture pain. Vertebro¬plasty is a minimally invasive procedure that not only provides immediate relief but continued and prolonged relief that may increase the patient's daily activity level, which in turn helps provide a better quality of life. In several studies it has been shown that in more than 90% cases it provide immediate pain relief.

 Some of the potential complications include leakage of the cement into the spine, surrounding structures, and vessels.