Posted 13 December 2008 - 12:57 PM
The following is an interesting article on bone density following SCI.
Osteoporosis After Spinal Cord Injury
What is osteoporosis?
Osteoporosis, commonly referred to as "brittle bones", is defined as a skeletal disorder characterised by compromised bone strength predisposing a person to an increased risk of fracture. In the general population approximately 2.4% of men and 5% of women aged 50 years have osteoporosis, increasing to 20% of men and 50% of women at 85 years. Also in the general population, women have a 1 in 3 and men a 1 -in-5 lifetime risk of sustaining an osteoporotic fracture. It is likely that ail patients with complete spinal cord injury (SCI) will eventually be affected by osteoporosis. Patients with incomplete cord injuries are also at risk but might not be as severely affected. Bone loss starts in the immediate aftermath of SCI and is greatest in the first year to 18 months, then continues at a slower rate thereafter. The spine is less likely to be affected probably due to the' weight-bearing effect of sitting. The arms are preserved in people with paraplegia but not in tetraplegia, while the lower limbs are affected in both.
Why does osteoporosis occur after SCI?
Why osteoporosis occurs so commonly in patients with SCI is not fully understood. As weightbearing is important for maintenance of bone, it may be that immobilisation and lack of muscle activity precipitates bone loss. Another possibility is that the bone's blood supply is affected, resulting in reduced nutrition and oxygen supply to the bone. In addition, vitamin D deficiency around the time of the SCI, due primarily to lack of exposure to sunlight, may exacerbate the problem. A number of other hormonal and chemical factors have also been studied, but their roles remain uncertain.
As the internal structure of bone thins, the risk of sustaining a fracture increases, even with seemingly little trauma such as failing during a transfer. It is estimated that 2% of patients with SCI have a fracture each year, although this increases with time since injury. For the reason outlined above, the legs are most vulnerable to fracture particularly around the knee. Younger people with paraplegia, who engage in a more active lifestyle, are probably more at risk of fracture. Unfortunately, osteoporosis usually does not present you with any symptoms until a
fracture occurs. In SCI, the diagnosis of fractures may be delayed due to lack of sensation in the lower limbs. Therefore any new swelling, deformity, colour or temperature change warrants early medical review as delayed diagnosis may result in further complications.
How is osteoporosis diagnosed?
The standard and most common investigation to measure bone density and diagnose osteoporosis is the Dual energy x-ray absorptiometry - DXA. This measures bone mineral content and bone mineral density. The results are then compared to a database of healthy young females to calculate scores. Most results are printed in graph form and your doctor will discuss them with you.
X-rays are generally not suitable to diagnose osteoporosis.
More recently other types of scan have been used to assess bone density including quantitative CT and ultrasound. Currently these are used mainiy in research studies rather than in standard practice.
As part of your assessment for osteoporosis your doctor will assess other risk factors and check some blood tests including your Vitamin D and calcium levels - Vitamin D deficiency is probably under recognised and needs to be corrected before other treatments to improve bone density are started.
Is there any treatment?
There are no national or international guidelines on treating osteoporosis after SCI. This is probably because osteoporosis has only relatively recently been studied and there is little data (or "evidence") that treatment prevents fractures (it will take many years for this to become available because of the need for very long follow up). There is, however, data that treatment improves bone density and therefore some centres, including ours in Stanmore, are offering treatment. (We are also involved in research projects on prevention and newer types of treatment).
The aim of osteoporosis treatment is reducing fractures. Prevention of falls and trauma (either in walkers or from wheelchairs!) is therefore an important part in management. Other risk factors are reversible - another good reason for your doctor to ask, and advise you about diet, alcohol and smoking. Some people are concerned
about taking too much calcium in their diet because they had been told in the past this can cause kidney stones - only in a very small minority of people with certain conditions can calcium in the diet do harm - ask your doctor if you are worried.
The standard treatment for osteoporosis is medication`usually with a drug known as a bisphosphonate - that inhibits bone loss. Other types of medication are used to treat osteoporosis in the general population but have not yet been tried after SCI. Bisphosphonates (eg Alendronate, Risedronate) are usually given in tablet form and can be given either daily or weekly. The medications are usually well tolerated but can cause side effects and some people should not use them - your doctor will consider all these things when discussing treatment with you. Newer drugs are available as monthly or yearly injections. Calcium and Vitamin D supplements are also recommended. Bone density takes a long time to improve and the expectation is not that it will return to your pre-injury level
but that it improves enough to reduce your risk of fracture. Currently we do not know for how long people need to stay on osteoporosis treatment. Our practice in Stanmore is to repeat the DEXA after 18 months of treatment to make sure there is a response to the drug - then continue for at least 5 years.
Physical treatments (eg vibration, electrical stimulation of muscles) have also been studied to help treat osteoporosis and more studies are underway but it is not yet clear how beneficial they will be. Many people hoped standing using tilt tables/standing frames would prevent osteoporosis but this is probably not the case (although there are other good reasons to stand!).
If you are worried about your risk of osteoporosis speak to your doctor.
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Broke my right hip. 
Didn't know it, of course, until the swelling got ugly. Turns out my bone density has gone to hell. Hip - down 16%; spine - up 1.5%. So, after the x-rays, the doc said I have to do Fosimax (sp) or the generic. A friend told me I should also do Calcium with Vitamin D. Anyone have some experience with these? Thanks. -Lynn
Murray, on Dec 9 2008, 08:27 PM, said:
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