Osteoporosis is a condition characterised by reductions in bone density. A low bone density is a risk factor for sustaining what is known as a minimal trauma fracture. Put simply a minimal trauma fracture is a fracture from stress that would not have broken normal healthy bone such as coughing.
At this stage the way that we determine if someone has osteoporosis is through a DEXA scan which measures the mass or density of the bone. The only problem with this method is that while we know how much bone is present, it doesn’t give us a picture of how structurally sound the bone is.
The inside of bones is similar to honeycomb in that it has many “spaces” in between the bony cross beams. The arrangement of these cross beams ultimately determines the strength of the bone. It is logical to assume the less bone there is (ie the lower the bone mass) the less bone there is to create these all important connections that give out bone strength.
There are however a few other considerations beyond the DEXA result that can help you to estimate your fracture risk. The first and most important of these is your fracture history. Like any other injury, if you have broken a bone you are more likely to break a bone in the future. There is however one major consideration with this – circumstance. If you fractured your leg because you fell off a horse that was in full gallop this would not be considered abnormal. Bone is strong but can only tolerate a certain amount of stress and like all substances has a threshold beyond which extra stress will result in injury. However if you sustained a fracture in your ribs while you were leaning on the car seat cleaning, this would be considered to be abnormal.
Other factors in bone strength are related to hormones and steroids. One of the important glands in your body that helps to regulate your calcium levels is the parathyroid gland. It keeps your blood calcium levels fairly constant within a small range. If blood calcium levels drop, your parathyroid gland will signal the body to start retrieving calcium from the bones to increase their concentration in the blood. As a result any changes to the parathyroid gland or its function can affect bone density.
Steroid based medications are commonly prescribed for the management of respiratory conditions and are also used in the management of pain. It is common for prednisone to be part of the management plan for conditions such as polymyalgia, rheumatoid arthritis, psoriatic arthritis and the list goes on. Prolonged and continuous use of steroids such as prednisone and cortisone can have an adverse effect on bone density. A one off cortisone injection will not have the same effect. In general more than 6 months of regular steroid medication is what has been shown to be detrimental.
There is a free online tool that can give you an estimation of your fracture risk taking into account the factors mentioned above as well as others. You simply need to have access to your DEXA result and you can fill in the rest accordingly.
The link is www.shef.ac.uk/FRAX