Osteoporosis is a disorder of the skeletal system. It is marked by low bone mass, microscopic deterioration of the bone, increase in bone fragility, and the susceptibility to fracture.
Osteoporosis and the incidence of fractures:
Bone is alive and is made up of osteoblasts (cells that make new bone), osteoclasts (cells that reabsorb bone), and osteocytes, which are considered the “great communicators,” due to their ability to coordinate activity between osteoblasts and osteoclasts.
Risk factors for osteoporotic fracture include:
Bone is at its strongest at the age of 30. While there is a steady yearly decline of about .5% until 1-2 years before menopause, there is a 2-5% yearly bone loss for this pre-menopausal period, as well as 2-5 year period after menopause. After that, there is 1% yearly bone loss for the remainder of life.
It is important to aim to achieve peak bone mass by using the following methods:
Following age 30, there is the aforementioned slow, steady decline in bone strength. Testing this strength - otherwise known as Bone Mass Density (BMD) - is done using a special kind of x-ray called DEXA (dual energy x-ray absorptiometry). Guidelines for those who should get measured for Bone Mass Density (BMD), using DEXA, include the following:
The World Health Organization (WHO) criteria for assessing disease severity is based on the “T-score,” which compares the BMD score against a normal 30 year old male or female in Standard Deviation (SD):
The National Osteoporosis Foundation Guidelines specify that women with BMD T-scores below -2 without other osteoporosis risk factors receive treatment. Women with BMD T-scores below -1.5 should also receive treatment if other risk factors for osteoporosis are present.
The World Health Organization (WHO) developed the FRAX Analysis as a way to predict who is at risk for fracture. FRAX Analysis is a computer program that takes into account age, sex, height, weight, and other factors. It is intended for patients over 40 who are not yet receiving pharmacologic treatment, and weighs various risk factors.
Treatment is recommended if 10-year risk of overall fracture is greater than, or equal to, 20% or 10-year risk of hip fracture is greater than, or equal to, 3%.
This test is a “bone turnover marker” that assesses the current level of the resorption of bone. The results of the NTX are used together with BMD (Bone Mass Density) to help assess the risk of fracture. It is measured in a simple urine test.
This kind of testing should be considered if the patient has more than expected bone loss for one’s age, or is having bone loss despite what is considered to be appropriate therapy. It measures results from blood and urine tests.
There are several factors that can contribute to bone loss in those with myositis. The inflammatory process contributes to the problem, as do the drugs commonly used to treat it.
Steroids, for example, decrease osteoblastic activity and calcium absorption, while increasing osteoclastic activity and calcium excretion.,An added problem is decreased sex steroid production. Also, those on methotrexate may experience possible bone loss. At this time, it is unclear if protein pump inhibitors (prilosec, prevacid, nexium) increase osteoporosis or decrease calcium carbonate absorption.
Because of increased muscle weakness, patients with myositis may do fewer weight-bearing activities. They may also be at greater risk for falls.
To reduce the risk of osteoporotic fracture, it is recommended that myositis patients use the lowest possible dose of steroids, exercise regularly, optimize vitamin D level, and obtain balance training if needed.
Treatment options for osteoporosis in those with myositis focus on two therapies: antiresorptive therapy and anabolic therapy.
Antiresorptive therapy slows the loss of bone and aims to reduce incidence of fractures.
- Given in doses of 60-120 mg per day
- Must be at least two years past menopause
- Use of raloxifene has shown a decrease in fractures of the vertebrae. There has been no evidence in decrease in hip fractures.
- A major benefit of this therapy is that there is a reduction in the incidence of breast cancer.
- Possible side effects include: thrombosis (blood clot), hot flashes (especially if a patient has gone through menopause), joint pain and leg cramps.
Bisphosphonate therapy (Fosamax, Boniva, Actonel, Reclast/Zometa)
- Alendronate (Fosamax)
- Taken orally
- For treatment: dosage is 10mg orally daily, or 70mg orally once a week (with and without vitamin D)
- For prevention: dosage is 5mg orally daily or 35mg orally once a week
- Ibandonate (Boniva)
- Orally: this is given at a dose of 150mg once a month.
- Intravenously: administered by a physician at a dose of 3mg every 3 months. The advantage of intravenous administration is that there is no gastrointestinal upset.
- Risedronate (Actonel)
- Orally: treatment and prevention doses are the same, i.e. 5mg each day and 35mg once a week, with and without calcium. Can also be given 150mg once per month orally.
- Zolendronic acid (Reclast/Zometa)
- Given once a year, intravenously, at a dose of 5mg. This benefits those who are otherwise susceptible to gastrointestinal upset when bisphosphonates are taken orally.
- Possible side effects include rare reports of atrial fibrillation (irregular heartbeat) and transient of flu-like symptoms
- Administered as a nasal spray; it is unclear if this treatment is effective
Hormone replacement therapy (HRT)/Bisphosphonate
Studies have looked at the effects of combining 0.625mg of estrogen with 10mg daily of fosamax; studies have shown an increase in BMD (Bone Mass Density) over the use of HRT alone.Possible side effects of bisphosphonate therapy include:
- gastrointestinal upset (when taken orally)
- atrial fibrillation (irregular heartbeat)
- osteonecrosis of the jaw (ONJ) [important information about ONJ]
- possible esophageal cancer (when taken orally)
- musculoskeletal pain
- possible increased risk of stress fractures if given in excess.
- Other questions that remain include: How long can patients remain on bisphosphonates? Does being on bisphosphonates for too long increase the risk of fracture? Should patients be rescued with Forteo? (see below)
Anabolic therapy “pushes” the body to make more bone. This type of treatment (Teriparatide: Forteo) may be indicated in patients who cannot tolerate bisphosphonates, who are not responding to current treatment, as evidenced by decreased body mass density or new fractures, or those with severe osteoporosis, those who are on steroids. or those with low turnover state (when there is very little bone formation or bone resorption; i.e., bone breakdown).
- FDA approved in dosage of 20mcg subcutaneous (under the skin) injection daily for a period of two years
- It is expensive: $700 per month
- Considered safe but should not be used by people with a history of Paget’s Disease or of skeletal radiation
Bone health should be assessed in all patients, using diagnostic tools discussed in this presentation. Patients can then be prescribed the appropriate therapy. These may include calcium and Vitamin D, a weight-bearing exercise program, and pharmacologic therapy.
Everyone’s treatment is different. All decisions about treatment should be made in collaboration with your physician and health care team.
For patients with myositis, it is important first to control/stabilize the disease process, use the lowest dose of steroid possible, exercise regularly, incorporate balance training if needed, and optimize your level of Vitamin D.
Treatment then needs to be monitored for changes and adjustments according to your particular needs at a given time.
Learn more about the Myositis Support Group, a free support and education group held monthly at Hospital for Special Surgery.
Summary prepared by Suzan Fischbein, LCSW, Myositis Support Group Coordinator