Bone spurs form when your body grows extra bone tissue in response to damage, stress, or friction at a joint. The process is essentially your skeleton trying to repair itself. When cartilage wears down, tendons pull repeatedly on the same spot, or a joint endures years of pressure, your body lays down new bone as a kind of bony scar. This repair process happens gradually, often over years, and most people who have bone spurs never know it.
Why Your Body Builds Extra Bone
The underlying trigger is almost always some form of mechanical stress. Healthy joints have a layer of smooth cartilage that cushions the ends of bones and lets them glide against each other. When that cartilage thins or breaks down, the exposed bone surfaces start grinding together. Your body responds by depositing new bone along the edges of the joint, attempting to stabilize the area and distribute force more evenly. The result is a small, smooth projection of bone that can range from a tiny bump to a noticeable ridge.
This same repair mechanism kicks in wherever tendons or ligaments attach to bone. If a tendon is under chronic tension, the constant pulling stimulates bone growth right at the attachment point. That’s why bone spurs commonly show up in the heel, shoulder, and spine, all areas where soft tissues are under heavy or repetitive load.
Osteoarthritis Is the Most Common Cause
The single biggest driver of bone spurs is osteoarthritis, the wear-and-tear form of arthritis that affects nearly every person to some degree as they age. As cartilage deteriorates, it develops cracks and fissures that eventually expose the bone underneath. The joint becomes less stable, and the body compensates by growing new bone at the margins. In the spine, narrowing discs between vertebrae create a similar effect, prompting spur growth along the edges of the vertebral bodies.
Excess body weight accelerates this process significantly. Carrying more weight increases the load on every weight-bearing joint, particularly the knees, hips, and spine. That extra force speeds up cartilage breakdown and drives more rapid bone spur development. Research has also found that fat tissue produces inflammatory compounds that concentrate in joint fluid and contribute to cartilage destruction independent of the mechanical load itself, meaning obesity promotes bone spurs through both pressure and inflammation.
How Spurs Form in the Heel
Heel spurs develop through a slightly different mechanism than joint-related spurs. The thick band of tissue running along the bottom of your foot connects to the heel bone, and when that band is under longstanding tension, calcium deposits gradually build up at the attachment point. Over months or years, those deposits harden into a bony projection on the underside of the heel. People who spend long hours on their feet, runners, and those with flat feet or very high arches are especially prone to this type of spur because of the sustained pulling force on the heel.
It’s worth noting that the heel spur itself often isn’t the source of pain. The inflammation in the surrounding soft tissue causes most of the discomfort, which is why many people with visible heel spurs on X-rays feel perfectly fine.
Shoulder Spurs and Repetitive Motion
In the shoulder, bone spurs typically develop as part of a progressive process driven by repetitive overhead movement. People who regularly reach above their heads for work or sports, painters, swimmers, baseball players, create friction between the rotator cuff tendons and the bony roof of the shoulder. Over time, this friction irritates and weakens the tendons. The body responds with bone growth along the underside of that bony roof, which then narrows the space even further and creates a cycle of increasing impingement.
This progression tends to follow a pattern tied to age. In younger adults, the damage shows up as swelling and irritation. By middle age, especially in people over 40 who have spent years doing overhead work, the condition can advance to visible bone spurs and partial or complete tears of the rotator cuff tendons.
Age Is the Strongest Risk Factor
Bone spurs are remarkably common in older adults. About 80% of men and 60% of women over age 50 already have them somewhere in the body. By age 70, that number climbs to 95% for both men and women. The reason is straightforward: decades of use gradually wear down cartilage and stress tendons, and the body’s bone-building repair response accumulates over a lifetime.
Beyond age and weight, other factors that increase your likelihood of developing bone spurs include joint injuries (even old ones from decades ago), physically demanding occupations, genetic predispositions toward arthritis, and poor posture that places uneven stress on the spine. A condition called diffuse idiopathic skeletal hyperostosis causes unusually extensive bone spur formation along the spine, with bony bridges connecting four or more vertebrae in a row. This condition is distinct from typical osteoarthritis and tends to run in families.
Most Bone Spurs Cause No Symptoms
One of the most important things to understand about bone spurs is that the majority are completely painless. Studies of the lumbar spine have found that the frequency of symptoms in people with bone spurs is no greater than in people without them. When someone with low back pain gets an X-ray and a bone spur shows up, the spur is usually an unrelated finding, not the cause of the pain.
Bone spurs only cause problems when they press on a nerve, restrict joint movement, or rub against other bones or soft tissues. In the spine, a spur that grows into the spinal canal can compress nerve roots and cause pain, numbness, or weakness radiating into the arms or legs. In a shoulder or knee, a spur can limit range of motion or catch during certain movements. But for most people, bone spurs exist silently for years and are discovered incidentally during imaging for something else.
How Bone Spurs Are Found
Standard X-rays are the primary tool for detecting bone spurs, though small or oddly positioned spurs can be easy to miss. A spur hiding behind another bone structure may appear as nothing more than a faint shadow on a flat image. CT scans and MRIs provide more detailed views, and newer 3D modeling software can reconstruct images from those scans to reveal spurs that were nearly invisible on conventional X-rays. MRI is particularly useful when the concern isn’t just the spur itself but the condition of surrounding soft tissues like cartilage, tendons, and nerves.
Because bone spurs are so common and so often harmless, finding one on imaging doesn’t necessarily mean it needs treatment. The decision to address a bone spur depends entirely on whether it’s causing symptoms. A spur that shows up on an X-ray but isn’t bothering you typically requires nothing more than periodic monitoring.
Slowing Down Bone Spur Development
You can’t completely prevent bone spurs if you live long enough, but you can slow the process. Maintaining a healthy weight reduces the mechanical load on your joints and lowers the inflammatory signals that accelerate cartilage breakdown. Regular low-impact exercise, like walking, swimming, or cycling, keeps joints mobile and strengthens the muscles that support them, reducing the stress on cartilage. Wearing supportive footwear, especially if you’re on your feet for long stretches, minimizes the repetitive tension on your heels.
Protecting your joints from injury matters too. Using proper form during exercise, taking breaks from repetitive overhead work, and addressing alignment issues like flat feet with orthotics all reduce the cumulative stress that eventually triggers bone growth. None of these steps will eliminate the natural wear that comes with aging, but they can meaningfully delay when bone spurs start to form and how quickly they progress.