Osteoporosis seems to be common among people with ankylosing spondylitis. The link may be explained by several factors like reduced spinal mobility and increased joint inflammation.
People with ankylosing spondylitis (AS) seem to be at an elevated risk of developing osteoporosis. A combination of factors like decreased physical activity and joint inflammation may cause this increased risk.
Osteoporosis is the loss of mineral density from your bones. It usually doesn’t cause symptoms until you fracture a bone.
AS is a type of arthritis that develops when your immune system attacks healthy cells in your joints. It usually causes pain and inflammation in your lower back.
Let’s examine what researchers know about the link between osteoporosis and AS.
Osteoporosis is common in the general population but seems to be especially common in people with AS. A 2020 research review indicated that people with AS have higher rates of osteoporosis and osteopenia compared to people without AS of the same age and sex. Osteopenia is a milder form of osteoporosis.
Rates of osteoporosis in people with AS have been reported between 19% and 62%.
In a 2023 study, researchers compared rates of osteoporosis in people with and without AS using data from medical records in Israel. The researchers found that the risk of osteoporosis was 1.83 times higher in people with AS than those without the condition.
A combination of
- reduced spinal mobility
- increased inflammation
- shared genetic factors
Reduced spinal mobility
People with AS often have lower back pain that can limit spinal mobility. It’s thought that back pain could cause lower exercise rates and outdoor sunshine time.
Your body needs regular exposure to sunlight to produce vitamin D. Vitamin D helps you absorb calcium from your food and helps
Physical activity also plays a critical role in preventing osteoporosis since your bones remodel and become stronger when stressed.
Increased inflammation
Reduced mobility alone doesn’t seem to explain the elevated rates of osteoporosis among people with AS since the rates are high even in the beginning stages when mobility is unimpaired.
Your body is constantly removing and depositing new minerals from your bones. It’s thought that inflammation from AS may increase the rate of bone reabsorption disproportionally compared to the rate at which your body deposits new minerals.
Genetic factors
There’s growing evidence that genetic factors may contribute to the development of osteoporosis in people with AS. Some genes that might play a role in speeding up bone breakdown and contributing to fracture risk in people with AS include the VDR and RANKL genes.
The development of AS isn’t well understood, but it’s strongly associated with the gene HLA-B27. As many as
In a 2022 study, researchers examined risk factors for AS and three other autoimmune diseases:
The researchers reported that having osteoporosis was associated with a 2.93 times higher risk of having ankylosing spondylitis.
Other factors that were associated with an elevated risk of AS in the study included:
- current smoking
- former drinking
- anemia
- uveitis
- irritable bowel disease
- gastrointestinal infection
Here’s a look at the symptoms of AS and osteoporosis.
Ankylosing spondylitis symptoms
Symptoms of AS tend to develop slowly and get worse over months to years.
The main symptoms are back pain and stiffness that:
- gets better with exercise
- doesn’t improve with rest
- is worse in the morning and night
- is around your buttocks
Osteoporosis symptoms
Osteoporosis is often considered a silent disease because it usually doesn’t cause symptoms until you fracture a bone. It often leads to fractures after minor falls or injuries.
It’s a good idea to speak with a doctor if you have unexplained joint pain you think might be caused by AS or another form of arthritis, especially if your symptoms are getting worse over time and don’t improve with rest.
It’s also important to see a doctor if you suspect you may have osteoporosis, especially if you’ve fractured a bone recently after a relatively minor injury.
Tests for ankylosing spondylitis include:
- review of your symptoms and medical history
- a physical exam
- blood tests to look for signs of inflammation and HLA-B27
- imaging tests, such as:
Osteoporosis is primarily diagnosed by measuring your bone density. Dual-energy X-ray absorptiometry (DEXA) at your hip and spine is generally considered the most reliable bone density test.
Treatment for AS includes:
- exercise and physiotherapy
- pain relievers like:
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- acetaminophen (Tylenol)
- opioids (for moderate to severe pain and only for short periods of time as prescribed by a doctor because they pose a risk of dependence)
- Other medications, such as:
- TNF inhibitors
- monoclonal antibodies
- JAK inhibitors
- corticosteroids
- disease-modifying antirheumatic drugs
- surgery
Treatment for osteoporosis includes:
- exercise to strengthen your muscles and bones
- vitamin and mineral supplements such as vitamin D and calcium
- medications, such as:
- estrogen
- testosterone
- bisphosphonates
- denosumab (Prolia)
- romosozumab (Evinity 7)
- parathyroid hormone analogs
Osteoporosis usually doesn’t cause symptoms until you fracture a bone. If your doctor thinks you’re at risk, they may recommend medications to help slow bone loss. Osteoporosis appears to be more common in people with ankylosing spondylitis.