Bone spurs are small, smooth growths of extra bone that form along the edges of existing bones, most often at joints. They develop when your body tries to repair damage or reinforce areas under stress, laying down new bone tissue in places it doesn’t belong. The process is gradual, typically unfolding over months or years, and it’s remarkably common: about 80% of men and 60% of women over 50 have bone spurs, and by age 70, 95% of both men and women have them.
Why Your Body Builds Extra Bone
Bone spurs aren’t random. They’re your skeleton’s misguided attempt at self-repair. The most common trigger is osteoarthritis, a condition where the cartilage cushioning the ends of your bones gradually wears away. Cartilage acts as a shock absorber and a smooth surface for bones to glide against each other. When it thins or breaks down, bones start making more direct contact, creating friction and inflammation at the joint.
Your body detects that damage and responds the only way bone tissue can: by growing more bone. It deposits new bony material near the damaged area, forming small projections called osteophytes. The intention is structural reinforcement, but the result is often a lump of bone that crowds the joint, presses on nearby soft tissue, or limits range of motion. This repair response is the central mechanism behind most bone spurs, regardless of where they appear.
Mechanical Stress and Repetitive Strain
Osteoarthritis isn’t the only path to bone spurs. Any sustained mechanical stress on bone can trigger the same repair response. Bone spurs tend to form on bones that absorb a lot of force, like your spine and heels, and at sites where tendons or ligaments attach to bone. When those attachment points are repeatedly pulled, strained, or inflamed, the bone underneath responds by thickening and extending outward.
Heel spurs are a clear example. The plantar fascia, a thick band of tissue running along the bottom of your foot, connects to the heel bone. When that tissue becomes chronically inflamed (a condition called plantar fasciitis), the constant stress at the attachment point triggers your heel bone to deposit extra calcium. Over time, a sharp, bony projection grows from the bottom of the heel. Factors like carrying extra body weight, spending long hours on your feet, or wearing unsupportive shoes all increase the mechanical load on these structures and raise the likelihood of spur formation.
Where Bone Spurs Form Most Often
Bone spurs can technically develop on any bone, but they cluster in predictable locations. The most common sites are:
- Feet and heels: especially at the plantar fascia attachment point on the heel bone
- Knees: along the joint surfaces where cartilage loss from arthritis is common
- Hips: at the edges of the hip socket, where weight-bearing wear accumulates
- Spine and neck: on the vertebrae, particularly where discs have degenerated
- Shoulders: around the rotator cuff area, where tendons meet bone
- Hands: at the finger knuckles, often visible as hard bumps in people with hand arthritis
These locations share two traits: they bear significant weight or repetitive force, and they contain joints or tendon attachment sites where cartilage and soft tissue are vulnerable to wear.
How Spinal Bone Spurs Develop
The spine deserves special attention because bone spurs here can cause more serious problems than in other locations. Between each pair of vertebrae sits a disc, a rubbery cushion that absorbs shock and allows your spine to flex. As you age, these discs lose moisture, shrink, and may crack. The body responds by producing extra bone along the vertebrae in an effort to stabilize the spine.
These spinal bone spurs can grow inward toward the spinal canal, the narrow corridor that houses your spinal cord and the nerve roots branching off from it. If a spur narrows that canal enough to press on the spinal cord or a nerve root, you may experience tingling, numbness, or weakness in your arms, hands, legs, or feet. Some people develop difficulty with coordination or walking. In severe cases, spinal cord compression can affect bladder or bowel control, and if the compression is serious enough, the nerve damage can become permanent. This process is particularly common in the neck, where it’s known as cervical spondylosis.
Risk Factors That Speed Up the Process
Age is the single biggest risk factor because cartilage loss and disc degeneration are cumulative. But several other factors accelerate the timeline. Joint injuries, even old ones from years ago, create localized damage that the body continues trying to repair. Excess body weight increases the mechanical load on weight-bearing joints like knees, hips, and the spine. Repetitive motions from certain jobs or sports concentrate strain on specific tendons and joints. Poor posture changes the distribution of forces along the spine, making certain vertebrae work harder than they should.
Genetics also play a role. Some people are more prone to osteoarthritis, which makes them more prone to the bone spur formation that follows. And because the process is so gradual, many of these risk factors compound over decades before spurs become large enough to cause symptoms.
Why Most Bone Spurs Go Unnoticed
The majority of bone spurs cause no symptoms at all. Many people have them without ever knowing it, and the spurs only show up incidentally on imaging done for other reasons. A bone spur becomes a problem only when it’s in a location where it can press on a nerve, rub against another bone, or restrict joint movement. That’s why two people with the same size spur in different locations can have completely different experiences: one feels nothing, the other has daily pain.
When bone spurs do cause symptoms, they typically produce a dull ache or stiffness in the affected joint, reduced range of motion, or sharp pain when the spur presses on soft tissue. In the knee, you might notice pain when bending or straightening the leg. In the hip, movement in any direction can feel restricted. In the spine, symptoms may radiate into the arms or legs depending on which nerve is affected.
How Bone Spurs Are Detected
Standard X-rays are the most common way bone spurs are identified, and they’re effective for spotting moderate to large growths. But X-rays are two-dimensional and susceptible to positioning errors, which means small spurs can be missed. MRI, often used to evaluate joint problems, is better at showing soft tissue but actually underestimates bone spurs. Research published in Osteoarthritis and Cartilage found that MRI detected only about 70% to 81% of bone spurs confirmed by CT scans in the knee, with the smallest spurs being the most likely to go unseen. CT scans are considered the gold standard for evaluating bone spurs because they provide detailed three-dimensional views of mineralized tissue, but they’re not typically ordered unless precise measurement matters for treatment planning.
For most people, the specific imaging method matters less than whether the spur is causing symptoms. A spur found on an X-ray that isn’t causing pain or functional problems generally doesn’t require treatment. The growth itself isn’t dangerous. It’s only the mechanical consequences, nerve compression, joint restriction, or tissue irritation, that create the need for intervention.