In women, osteoarthritis has some specificities that it is important to be familiar with even if only to avoid certain behavioural risk factors, sometimes typically feminine
Is osteoarthritis more or less common in women than men?
In both sexes, the incidence of osteoarthritis increases with age. In women, osteoarthritis is rare before the age of 45 years but its incidence increases significantly after the menopause (45-55 years). It is estimated that osteoarthritis, in particular osteoarthritis of the hand or knee, is about twice as common in women than in men.
Osteoporosis is also more common after the menopause.
Does the latter promote osteoarthritis?
No. Osteoarthritis and osteoporosis are actually two common pathologies in women after the menopause. However, they are two independent and different diseases: osteoporosis, bone disease, is a demineralisation by increasing bone resorption, whereas osteoarthritis is a joint disease.
For a reason still unknown, these two diseases are seldom present in the same person. For example, hip osteoarthritis is rare in women who have had a femoral neck fracture. A curious phenomenon has also been demonstrated: digital osteoarthritis is rare in women with vertebral compression of osteoporotic origin.
Why does osteoarthritis increase after the menopause?
Is it a hormonal problem?
The increased frequency of osteoarthritis after the menopause has of course pointed to a possible role of hormonal impregnation, including by oestrogens, especially since the presence of oestrogen receptors in the cartilage has been demonstrated.
Studies conducted in this field have produced conflicting results, however. Some studies indicate that oestrogen increases the amount of joint cartilage (in volume); though curiously, other studies suggest that an oestrogen deficiency, which promotes osteoporosis, is a protective factor against osteoarthritis.
Can hormone replacement therapy offered to women after the menopause
prevent osteoarthritis as it prevents osteoporosis?
Hormone replacement therapy is intended to offset the oestrogen deficiency characteristic of the menopause. An extensive epidemiological survey conducted in the United States in the town of Framingham showed no significant change in the frequency of knee osteoarthritis in women taking hormone replacement therapy.
The most recent studies indicate that this treatment has no protective effect or that it promotes the onset of osteoarthritis. The methods used in these studies are very different, but no argument currently enables affirming that this treatment has a protective role against the onset or progression of osteoarthritis.
Is it possible to prevent osteoarthritis in women?
Many risk factors for osteoarthritis have been identified, for example, obesity. Of these, some are called "modifiable" because they are related to lifestyle, in particular to eating habits
What are the factors leading to osteoarthritis in women?
Magnetic resonance imaging has revealed that the volume of articular cartilage is smaller in women than in men, even taking into account the difference in size of the joint surfaces. This phenomenon seems even more pronounced after the age of 50 years.
Foot deformities, either spontaneous and permanent (e.g. hallus valgus) or induced and temporary but repeated (wearing high-heeled shoes) appear to cause a significant risk of knee osteoarthritis.
Elegant and flattering high-heeled shoes promote knee osteoarthritis…
High-heeled shoes alter the normal dynamics of the ankle, leading to increases and changes in the distribution of pressure at the knee during walking. These phenomena of compensation required to maintain the stability of the knee could promote knee osteoarthritis, which explains why it is frequently bilateral in women.
For some, it is also possible that shoes with high but wide heels provoke the same mechanical phenomena as stiletto heels: they even tend to be more dangerous, as being more comfortable they are therefore worn more often!
Some contributing mechanical factors are encountered in specific cultures. It has notably been shown that frequent and prolonged time spent in a crouching position (traditional rest position in China) is a predisposing factor for osteoarthritis of the hip. In addition, in North Africa, there has been an increase in knee osteoarthritis (compared with France). This difference could be sitting in a cross-legged position which is more common in these regions.
Being overweight promotes osteoarthritis by increasing the load on the joints of the hip and knee. This is one of the main contributing factors for osteoarthritis, even greater in women than in men, especially for the knee rather than the hip
Why is excess weight so significant?
It is easy to understand that obesity tires weight-bearing joints (hip and knee) and thus promotes the onset of osteoarthritis by mechanical wear.
Obesity is defined medically as "excess weight by increase of the adipose tissue mass". We talk about obesity, when adipose mass is more than 25 to 30% of the total weight in women. Thus, the body mass index (BMI) is a ratio (weight in kg) / (height in cm) 2 which expresses corpulence. When it is over 30 it signifies obesity.
Obesity can also worsen pre-existing osteoarthritis, which is reflected in particular by more intense pain in obese osteoarthritic patients than in patients of normal weight.
A recent study shows that the relationship between obesity and the risk of osteoarthritis begins very early in life. An analysis of risk factors that could potentially promote hip osteoarthritis justifying a total hip replacement has shown a risk 2 times higher in obese women, and 5 times higher in obese women from the age of 18 years
A more intriguing and very recent notion that also concerns both men and women, is that the risk of osteoarthritis related to excess weight is higher in subjects with a low birth weight who become obese in adulthood.
The relationship between body weight and osteoarthritis is even more subtle and may involve metabolic processes, since obesity seems to promote osteoarthritis of the hand.
Osteoarthritis is not always linked to excess weight, but the relationship between osteoarthritis and being overweight is an excellent additional reason to maintain a normal weight.
Are some forms of osteoarthritis specific to women?
No, but some forms of osteoarthritis are significantly more frequent in women. Besides osteoarthritis of the knee, digital osteoarthritis is more common and also more painful than in the male forms.
This relates to osteoarthritis of the distal interphalangeal joints (DIP) and the proximal interphalangeal joints (PIP), showing at this level a localised increase in volume described under the name of Heberden's nodes (DIP) or Bouchard's nodes (PIP).