Osteoarthritis is often considered the price to be paid for living a long life. A privilege of the elderly! In some ways this fact holds true, in that the disease is definitely more common in the older age group, with about 30% of those over the age of 65 years of age being affected, increasing to over 50% in the 85+ age group1. Therefore it is true to say that the older you become the more likely you are to develop the disease. However, as suggested by the statistics presented above, osteoarthritis is not only limited to the elderly but can affect adults of any age. In fact, when all age groups are considered, 15% of Australians at any one time are dealing with the impact of the condition; being more prevalent amongst females, with an estimated 1.62 million people coping with osteoarthritis in 20072.
An important point to make is that the impact of this disease is not insignificant. Musculoskeletal conditions (in which osteoarthritis is included) resulted in a greater reduction in the quality of life compared to other health problems, including endocrine, gastrointestinal, respiratory, neurological, and cardiovascular diseases3. This reduction in quality of life relates to a difficulty in performing usual or desired everyday activities, with 38-52% of those affected being limited in their daily tasks4. Further to this, arthritis is a leading cause of disability, only surpassed by total hearing disorders5. This unfortunate reality, however, has not been ignored with arthritis being declared as the major area of focus for health and well being over the last 10 years, which the World Health Organisation (WHO) termed as the bone and joint decade.
So having set the scene that osteoarthritis is common and often has a negative impact upon a sufferer’s life, let us now focus on what is meant by the term osteoarthritis. The term itself is a composite of greek, where osteo means bone, arthro refers to joint, and itis implies inflammation. Therefore, in totality it means inflammation of bone and joint. However, this in a pure sense is too broad a term as there are over 100 different types of joint diseases, with many of them characterized by the presence of inflammation. So how has this term come to mean was it does today? Well, for many years any disease of the joint was called osteoarthritis, however, over time the other forms of arthritis have defined themselves and become recognized as separate entities, such that in today’s language, the term osteoarthritis now comes to refer to particular type of joint disease.
For us to understand what Osteoarthritis actually is, we need to understand why it is that we have joints and what structures within a joint are needed to perform these functions. With regards to the former I would like you to imagine what life would be like if you did not have any joints. Imagine not being able to bend your knee, rotate your head, or close your hand! I am sure that reflecting on these questions will bring to mind why it is that most living species in this world have evolved a skeleton of joints. In the most basic sense, all the reasons for the existence of joints reduce to the need we have to interact with our environment. Therefore, the structure of a joint has evolved to allow movement in a very efficient way, especially considering we often move certain joints a thousands of times a day!
However, the ability to move at different points in our being comes at the cost of stability, that is the greater the number of joints the greater instability as a whole. Compare the stability of an articulated toy snake to a stick. In essence, the point that I am leading to is that joints have therefore evolved mechanism to provide a degree of stability. The manner and extent of stability is dependent upon the function of each particular joint. For example, the pelvis is a lot more stable than the shoulder, the latter of which needs to move through a very wide range of motion. Therefore, joints are uniquely composed of specialised tissues/structures that provide a varying degree of mobility and stability specific to the particular function of that joint.