Bone Density After a Spinal Cord Injury

Following a spinal cord injury, an individual can suffer from bone loss and muscle atrophy, causing bone density to decrease from the point of injury onwards. As such, being a SCI patient increases the risk of osteoporosis, as well as fractures to bones.

A lack of mechanical loading and movement is often the reason why bone loss and muscle atrophy in spinal cord injury patients occur, and osteoporosis is one of the most commonly found diseases which are directly to blame for a decrease in bone density after a spinal cord injury and later in life.

What is osteoporosis?

Also known as porous bone, osteoporosis is a disease in which bones become less dense, increasing their weakness, brittleness, and overall chances of breaking. Unlike the normal process of creating new cells, where old ones become re-absorbed, osteoporosis causes this process to become unbalanced. Bone loss is more rapid than the bone growth, and this leads to the gradual thinning of the bone.

Throughout our lifetimes, we gradually increase and then lose our bone density as we get older. It increases until an individual is in their late 20s, and with plateau until around the age of 35 when it will begin to decrease. Women, in the first few years of menopause, tend to lose bone density very quickly, due to the hormonal changes to estrogen levels the body.

This disease of the bone has many causes, and these can differ between men and women. Although osteoporosis and osteopenia usually affect older people, it can happen at younger ages also. It is thought that the differences in gender causes is largely in part down to hormones, but can be affected by glands and external factors, such as alcoholism and hysterectomy procedures.

Other external factors which can cause, or increase likelihood of osteoporosis include:

• Disorders of the pituitary glands and metabolic disturbances
• Reduced levels of sex hormones (oestrogen and testosterone)
• Family history of osteoporosis
• A BMI of 19 or less
• Eating disorders and poor nutritional status
• Long periods of inactivity or bedrest

Why does osteoporosis occur so often in SCI patients?

Osteoporosis in SCI patients is a much different situation than those who experience it in the general population. It is believed that around 80% of SCI patients will experience either osteoporosis or osteopenia following their injuries. Unfortunately, in some cases following spinal cord injuries, signs and symptoms of osteoporosis can be seen as soon as six weeks post-injury, with bone density decrease rounding off a few years after that.

Bone loss generally occurs below the point of injury, and so dependent on the severity and point of injury, some people will find more of their body affected than others. Bone density decrease has, in fact, been cited to be more severe in those with a complete spinal cord injury, and between 30% and 40% of decreases of bone density found occur in the legs.

Osteoporosis and bone density after SCI

Where osteoporosis, or its intermediate stage of osteopenia, causes bones to thin, it increases the chance of fractures in patients, even if they find themselves paralyzed. Fractures, although to most seem inconvenient but not deadly, fractures in those with SCI can be highly debilitating and even sometimes fatal. A sad but honest consequence of osteoporosis.

In the US alone, more than 300,000 people over 65 years of age (without SCI) sustain fractures, usually of the hip, on a yearly basis, and 30% of these die within a year. People with osteoporosis following a SCI will most likely be younger than this, and it can be hard to understand that although usually a condition in older people, osteoporosis after a SCI is common, and indeed likely, at any age.

It can cause an overwhelming and emotional loss in independence and function, on top of that which may have been lost in a spinal cord injury, however osteoporosis is largely preventable and even treatable with today’s medicines, and there are things you can do in order to alleviate osteoporosis post-SCI.

Preventing and diagnosing osteoporosis in SCI

Prevention of osteoporosis is something an individual can work on throughout their life, and it is never too early to start thinking about good bone health! Prevention in children and all the way through adolescent years should concentrate on nutritious diets, with plenty of calcium and vitamin D. Participating in regular exercise and physical activity is advised, as is the avoiding of second-hand smoking.

Although there are similar points for adults in regards to maintaining healthy bones, other methods include avoiding smoking and heavy drinking, and being mindful of extreme dieting, weight-loss diets and eating disorders.

Of course, as we have already read, it is unfortunate that SCI patients have an 8/10 chance of being diagnosed with osteoporosis, regardless of their bone health prior to their injury. We will now look at how to diagnose osteoporosis.

Diagnosis of osteoporosis will usually start with a look at your family history of bone disease, and look at your personal medical history. Of course, if you have recently acquired a spinal cord injury, this will be very pertinent to the diagnosis process.

It is more than likely the next step would be to have a bone mineral density (BMD) test, which is different than a traditional X-ray. Because these cannot measure bone density, the BMD test is a helpful alternative. There are many ways to measure BMD, but the most common is DXA (dual-energy X-ray absorptiometry). This low radiation can detect small percentages of bone loss and helps your health care provider detect osteoporosis and predict your risk of bone fractures.

Treatment options if a SCI patient breaks a bone

The University of Washington studied osteoporosis in SCI patients, and collated the positive and negative factors of two kinds of treatment in osteoporosis.

• Conservative/non-surgical treatments cost less, and the procedures are non-invasive, however this can be slow and the requirement of some braces can cause skin breakdown.

• Surgical treatment can allow a range of motions to be started early, and hardware used can immediately stabilize bone. There also tends to be less shortening and/or angular deformity, but of course, the standard surgical risks apply which include the non-healing of surgical wounds. This can lead to local or systemic infection and repeat surgeries, and with internal hardware being used, this hardware can loosen or need replacing in the future.

The SCI community and osteoporosis moving forward

Today’s spinal cord community and the medicines and treatment available to patients are always developing and growing. With a large percentage of SCI patients experiencing osteoporosis, there is much literature on the subject, and so even if this is the case, there are many forms of treatment you can consider.