Foot and Ankle
How your feet work:
Feet have a complex structure consisting of 26 bones, more than 30 small joints (where bones meet) and many muscles, tendons, ligaments and nerves.
Problems in the feet and ankles are often, but not always, associated with arthritis.
Most feet have an arch shape that spreads the body's weight evenly over many bones and joints. Feet with lower arches tend to be more flexible, while feet with higher arches are generally less flexible. High or low arches aren’t necessarily a problem but they can increase your chances of developing other foot problems.
The structure of the foot changes as we get older or if arthritis affects the foot joints, and many people will notice changes, particularly in the arch of the foot.
When to see a doctor
For most people foot problems can come and go without any prescribed treatment, or can respond well to self-treatment.
However, if you have a known condition such as rheumatoid arthritis, scleroderma or diabetes, you should discuss any new foot problem with your rheumatologist, your GP or a podiatrist.
Even if you don't have any significant health conditions, you should still seek help if your foot problem:
- involves ulceration of the skin or is infected
- impairs the blood flow to the skin
- has caused pain for more than three months
- is getting noticeably worse
- is changing the colour of your skin, especially if it's dark blue or black
- is leading to progressive changes in the shape of your foot
You should also seek help if you develop foot problems and you have increased swelling, you're on drugs which suppress your immune system (including steroids or biologics) or if you have a history of poor skin healing.
How are foot problems diagnosed?
In most cases a simple clinical examination is all that is required. This usually involves looking carefully for signs such as swelling, combined with a short hands-on exam to work out which structures might be involved. Sometimes it is helpful to have the person walk up and down to see what happens during weight-bearing and routine activities.
It is less common for foot problems to require blood tests or imaging (for example, X-ray or ultrasound) to reach a diagnosis.
The feet and ankles can be affected by several types of arthritis, including osteoarthritis and inflammatory arthritis.
Osteoarthritis can affect any joint in the foot. Osteoarthritis is a chronic problem that may cause episodic pain and swelling in a joint or joints; it can also cause bone enlargement. As people get older, osteoarthritis can be linked to changes in the shape of feet, which may cause pain.
Osteoarthritis often affects the big toe joint. The joint will become stiffer and the range of movement will be reduced. Often the bones become larger and knobbly due to an overgrowth of new bone. These changes may accompany a bunion (a lump on the side of the big toe joint). You may also notice a bunionette (a lump on the side of the little toe joint).
Recent findings suggest that osteoarthritis is more common in the arch area of the foot than previously thought. Osteoarthritis can also develop in the ankle, but this is usually following a previous injury or damage to the joint from long-standing inflammatory arthritis. Osteoarthritis in the feet often accompanies osteoarthritis in other joints.
There are various forms of inflammatory arthritis, which can affect feet in different ways.
- Rheumatoid arthritis can affect many joints in the feet.
- Reactive arthritis usually affects the ankle or the area around the heel. It may also affect the toes, causing pain and swelling, which is known as dactylitis.
- Psoriatic arthritis often causes dactylitis.
- Gout most commonly affects the big toe joint. It is a very painful type of arthritis. Gout causes severe inflammation and makes the joint red, hot and swollen during an attack, which typically lasts one to two weeks.
- Without treatment, repeated attacks can cause permanent damage to the joint and lead to osteoarthritis. It is caused by the formation of urate crystals in a joint. However, gout can usually be well controlled with medications.
- Ankylosing spondylitis mainly affects the spine but may also affect the heels
Apart from problems in the joints themselves, people with inflammatory arthritis may have inflammation and discomfort in the tendons and the other soft tissues in the feet. The part under or behind the heel where the tendons attach to the heel bone (the Achilles tendon) is quite often affected in this way.
Dactylitis causes pain and swelling, usually in just one or two of the toes and can be referred to as 'sausage toe'.
Connective tissue disease:
Raynaud's phenomenon is a circulatory problem that causes the blood supply to certain parts of the body to be reduced, especially when exposed to cold conditions. It more commonly affects fingers, but it can also cause toes to temporarily cold and numb and turn white, then blue, then red. These attacks often only last a few minutes, and moving into a warmer environment often stops the attack. Wearing warm gloves and socks may help to prevent an attack.Raynaud's phenomenon can occur with the conditions:
- rheumatoid arthritis
- systemic lupus erythematosus (SLE)
Watch out for ulcers on the toes, or a colour change which doesn't go away as quickly as usual. These problems are usually very painful. If you develop one of these symptoms, you should see your doctor or contact your rheumatology nurse specialist as soon as possible.
Sometimes with lupus the joints and tendons are affected and you may notice that the toes drift outwards and the arches may flatten. This can be painful and may cause a feeling of stiffness after periods of rest.
Why does foot pain become persistent?
In most cases foot problems will not become persistent. Painful heels for instance can settle down spontaneously even after many months of causing trouble. Some foot problems though will go on to be persistent, osteoarthritis is a good example.
If you have foot symptoms that have persisted for more than three months it's worth seeking a professional opinion.
Most foot problems will be helped by finding footwear that has more room and is more comfortable, and by losing weight if you're overweight. A number of specific treatments can also help.