Introduction
Ankylosing spondylitis (AS) is a chronic inflammatory condition that mainly affects the spine and the joints connecting the spine to the pelvis. It leads to stiffness and makes it harder to move the back. Knee osteoarthritis (OA), on the other hand, is a common joint disorder where the cartilage in the knee gradually wears away, causing pain and making movement more difficult. At first glance, these conditions seem unrelated because they target different joints. However, AS can significantly increase the risk of developing knee OA. This article explores how the effects of AS—through changes in movement and increased inflammation—can speed up the progression of knee osteoarthritis.
What Are Ankylosing Spondylitis and Knee Osteoarthritis?
AS usually appears in young adulthood and progressively stiffens the spine due to ongoing inflammation and extra bone growth, which can even fuse parts of the spine together. It occurs more often in men and is commonly linked to other joint and systemic diseases, such as psoriatic arthritis and certain bowel diseases. In contrast, knee osteoarthritis typically develops in older adults, as the cushioning cartilage in the knee joint slowly degenerates over years of use.
Although these conditions affect different areas, the changes in posture and gait caused by AS can increase the pressure on the knees. Inflammation from AS is not limited to the spine—it can travel throughout the body, affecting other joints like the knees as well.
Treatments for AS focus on medication to reduce inflammation and physiotherapy to maintain flexibility. Strategies that help control inflammation and preserve movement not only help the spine but may also protect the knees from further damage.
How AS Changes the Way the Body Moves
One hallmark of AS is spinal stiffness and the gradual loss of the spine’s natural curves due to new bone formation. This often causes people to lean forward, leading to changes in both posture and walking patterns. To compensate, individuals shift more weight onto their knees.
Imagine a building with inflexible support beams—the floors below have to absorb more pressure to maintain stability. Similarly, when the spine loses its ability to move and flex, the knees must absorb more stress during daily activities.
This added stress hastens the wear and tear on the knee cartilage, increasing the risk of developing OA at a younger age and causing it to progress faster. Research has shown that people with AS tend to walk differently and put more strain on their knees than those without AS, further increasing the likelihood and speed of knee OA.
The Role of Inflammation
Mechanical stress is only part of the story. The inflammation at the core of AS can also impact the whole body. Chemical messengers produced during inflammation circulate in the bloodstream and can trigger irritation and swelling in other joints, including the knees.
This chronic, low-grade inflammation gradually damages the soft tissues and cartilage inside the knee joint, causing OA to progress even faster. When you combine this inflammatory effect with the mechanical stress from altered movement, the risk to knee health is even greater—a true “double threat” to healthy joints.
That’s why treating AS isn’t just about addressing back stiffness or pain. It’s also about managing inflammation throughout the body to help protect other joints, especially the knees, from premature damage.
What This Means for Treatment
Recognizing that AS can impact the knees allows for more effective and proactive treatment plans. Early detection of movement changes and proper intervention can help prevent or delay serious knee damage.
Treatment often includes specialized physiotherapy to improve walking patterns, strengthen the muscles around the knees, and enhance overall balance. Anti-inflammatory medications can slow down the breakdown of joint tissue, and maintaining a healthy weight further reduces stress on the knees.
The best care comes from a team approach that includes rheumatologists, physiotherapists, and orthopedic specialists working together. Coordinated treatment strategies can reduce pain, preserve mobility, and improve quality of life for people dealing with both AS and knee OA.
Living with Both Conditions
Managing both ankylosing spondylitis and knee osteoarthritis can make everyday activities a bigger challenge. Tasks like walking, climbing stairs, or standing for long periods may become more difficult and tiring.
Understanding how these two conditions are linked—through changes in movement and widespread inflammation—empowers patients to stick with comprehensive treatment plans. Tackling both conditions together with a focused, team-based approach can significantly reduce pain, enhance independence, and improve daily life.
Conclusion: Looking Ahead
In short, ankylosing spondylitis can accelerate the development of knee osteoarthritis by altering how the body moves and by creating ongoing inflammation. Spinal stiffness puts extra load on the knees, while inflammation speeds up the breakdown of knee cartilage.
Early diagnosis and coordinated, comprehensive care are essential to slow this process. As new research emerges, treatments that address both the mechanical and inflammatory components of these conditions will help people maintain healthier joints and enjoy more active lives.
By looking at ankylosing spondylitis as a condition that impacts more than just the spine, healthcare professionals can better protect joint health and help patients thrive.
