The articular cartilage that lines our bones is a particularly special material. The cartilage has developed to allow high levels of activity. The average adult takes between one and two million steps a year. Each will load the cartilage. The load experienced in the joint is increased significantly with activities such as getting out of chairs, climbing stairs and running. The cartilage can withstand considerable load over the course of our lifetime.
Osteoarthritis can happen for a number of reasons.
There is certainly genetic predisposition in some patients and in these patients, who frequently have a family history of ‘wear and tear’ arthritis, the condition typically starts in their forties and fifties or later, with discomfort and stiffness in the hips and knees. The same patients might be aware of arthritis in the hands and/or feet prior to this.
While the majority of arthritic hips show typical appearances as demonstrated elsewhere, osteoarthritis can occur secondary to previous problems in the joint such as malalignment of the joint caused by childhood hip disease or an infection. These processes can result in articular cartilage damage. Similarly, previous trauma with broken bones in the hip, femur or pelvis which may result in damage to the articular cartilage or mal-alignment of the joint, can cause increased wear and tear.
Patients can present with very much more complicated problems as can be seen in the examples below:
‘Secondary osteoarthritis’ can also occur as a consequence of more rare conditions such as ‘osteonecrosis’ where the blood supply to the bone can be affected, resulting in collapse of the bone and degeneration in the overlying cartilage.
Secondary osteoarthritis can also occur in association and at the ‘end stage’ of an inflammatory arthritis, such as rheumatoid or psoriatic arthritis. Thankfully, more modern treatments for these conditions will likely reduce this situation. It is important and, I hope, reassuring to know that hip replacement for these indications can be very successful in treating the resulting pain, deformity and restricted movement. Results in these circumstances are as consistent and rewarding as those for more standard primary osteoarthritis.