What causes knee osteoarthritis?

So, Professor Goss, can you please tell us the causes of knee osteoarthritis? So, osteoarthritis of the knee can be associated with certain factors that may contribute to the development of wear and tear in osteoarthritis. Our joints, and our knee joints specifically also, are exposed to a low level of trauma every day. With time, this leads to wear and tear and the cartilage starts to wear out in the knee joint and that leads to the development of osteoarthritis. The exact cause of osteoarthritis sometimes cannot be found and is unknown and that's what we call primary osteoarthritis and that's the commonest type of osteoarthritis. But there are certain factors that have been shown to be associated with the development of osteoarthritis in general and osteoarthritis of the knee. These factors are previous trauma, so if there's been a previous injury to the knee where there's damage to the joint surface or the cartilage, they're having what we call inflammatory arthritis such as rheumatoid arthritis or gout which is elevation of the level of uric acid as as well. Having a high BMI, Body Mass Index, or obesity leads to early development of osteoarthritis because the amount of weight that's transmitted to the knee is increased and that leads to wear and tear of the joint itself. And finally, sometimes associated with certain other conditions, So having previous infection in the joint that could have destroyed the joint, having had damage to the joint itself, another joint such as having a deformity that can lead to the development of osteoarthritis in the knee. For example, if somebody has a problem with their ankle, with a previous for example ankle tibial fracture, that can lead to development of osteoarthritis, secondary to that and vice versa. But the commonest cause is usually unknown, the most common thing is wear and tear, development of osteoarthritis, without any unknown cause, there are certain genetic factors and there are certain biological factors that have been shown to predispose to the development of osteoarthritis. Finally there is a strong association of family history with the development of knee osteoarthritis and also women are more predisposed to developing osteoarthritis than of the men generally speaking.