Arthritis

Arthritis, also known as joint inflammation, is a condition where bones that are a component of joints wear away the cartilage in between themselves and begin to rub against each other, wearing the bones. The result of this can be developments such as swelling, pain and stiffness in the joint itself. Although, these are just more basic forms of the symptoms and there are many others that come and go with the different forms of the disease. Over long times arthritis of all forms will begin to make daily tasks a struggle, with arthritis in the knees it will become difficult to perform tasks like climbing stairs and walking on upward or downward slopes. If you have arthritis in your elbow you may find it difficult to bend your arm and hold items.

newsnetwork.mayoclinic.org

There are over one hundred different forms of arthritis, but the two most common forms are osteoarthritis and rheumatoid arthritis. Osteoarthritis, which call also be known as 'wear-and-tear' arthritis, is the most well-known form of arthritis. It begins with the bones in the joint wearing away at the joint itself, whether it be through over-exercise, an injury, or obesity, pressure is put against the ends of the bones and wears away at the cartilage. After the cartilage has been worn away the bones rub up against each other, without the cartilage there to stop them from doing so, the bones press and chip away at each other, leaving shards of bone inside the arm itself. Rheumatoid arthritis, while similar to osteoarthritis, is in itself, something almost completely different when it comes to how it happens. The origin of the disease comes from when, for an unknown reason, the immune system, which usually would protect us from viruses and bacteria, instead attacks the joints. Due to this the tissue that lines the joints, known as the synovium, tends to thicken, resulting in swelling. If this goes unchecked and is ignored, the cartilage, like in osteoarthritis, breaks away and the bones soon chip away at each other, often resulting in weaker and unstable joints, in rarer cases joint deformity and many other unfortunate circumstances.

theconversation.com

There are many different things that contribute to the development of any form of arthritis, however, there are a few main factors that add to the risk of getting arthritis.
Genetics, the disease, in all forms, has been noticed to transition through genetic or family bloodlines. Injuries, if left unacknowledged, joint injuries, even if they appear to be alright and treated properly, can soon develop arthritis if the joint is repeatedly injured and constantly has weight on it.
Weight, if the skeleton endures an unhealthy amount of weight on the joints it can press the bones in the joints closer together, letting the cartilage wear away even quicker than the anticipated rate for more common forms of arthritis.
Age, it has been identified with arthritis that people over 65 have an around fifty percent chance to develop the disease in their joints if they haven't experienced it or are experiencing it already.
Repetitive actions, such as lifting boxes from one place to another, applies constant strain onto the joints in use, especially if it is for an extended period and then the person proceeds to lay down and not exercise the joints or use them.

A case of Rheumatoid Arthritis.
gettyimages.fi

Gender, arthritis has been found to be common in women than men, although there is no scientific diagnosis as to why this happens.
There are many myths surrounding arthritis and how you can get it, especially one of the more common ones like 'If you crack your knuckles, you will get arthritis', this is in fact, false. My science teacher told me so so you can bring it up with him. But, there are many other myths surrounding arthritis and how it can affect your body. There are other myths than the ones I will bring up here, if you wish to look over the others they will be from the sources I will have.

1. Only older people get arthritis, this is incorrect. There are over 300,000 cases of infants, children, and teenagers, having the disease in its different forms in their earlier stages of life.
2. All pain in the joints is arthritis, this is incorrect. There are other conditions such as tendonitis and even in some cases, it can be simple as soft tissue damage that can appear to be arthritis at first.
3. Taking it easy is the best thing for arthritis, this is incorrect. Regular exercise without overuse of the joint can be helpful to treat the joint, it is not a cure though.
4. There is nothing you can do about arthritis, this is incorrect. While there is not an absolute cure for arthritis, regular exercise, reducing weight, having both time to relax and time to be active, sleeping well and having a healthier diet can assist, but not provide any medical cure, with arthritis.
5. Applying heat to the joint is better than applying ice, this is incorrect. Both elements can help with the pain of arthritis in different situations, heat can be better for joints in the mornings while icing the pain can be more helpful before going to sleep. Both assist in dealing with the pain though.

Sources - 

arthritis.org

southerncross.co.nz

healthline.com

blog.arthritis.org

health.clevelandclinic.org