A bone contusion, commonly called a bone bruise, is an injury to the inner structure of a bone that causes microscopic damage without a visible fracture line. It sits in a gray zone between a simple soft tissue bruise and a full break. The pain tends to feel like a deep, throbbing ache that lingers far longer than a typical bruise, often taking many months to fully resolve.
How a Bone Bruise Differs From a Fracture
Bones aren’t solid all the way through. Beneath the hard outer shell (cortex) is a spongy interior filled with tiny struts of bone tissue and marrow. When enough force hits a bone to damage this interior network but not enough to crack through the cortex, the result is a bone contusion. Think of it like a dent in the internal scaffolding: the bone’s outer surface looks intact on an X-ray, but the inside has microscopic breaks, bleeding, and fluid buildup in the marrow.
A full fracture, by contrast, produces a clear break line that shows up on standard imaging. Bone contusions are sometimes called “occult” injuries because they’re invisible on X-rays. They only show up on MRI, where the excess fluid in the damaged marrow creates a distinctive bright signal. That’s why someone with significant bone pain after a fall or collision may get normal X-ray results and still have a real injury that needs attention.
Where Bone Bruises Happen
Bone contusions can occur in any bone, but the knee is one of the most common locations, especially in athletes. They frequently accompany ligament injuries. When the ACL tears, for example, the shinbone and thighbone often slam together in a specific pattern, leaving bone bruises on both sides of the joint. Bone bruises in both the inner and outer compartments of the knee can even help doctors predict the type of ligament tear that occurred.
Outside the knee, bone contusions commonly affect the ankle, wrist, hip, and foot. Direct blows (a kick to the shin, a fall onto an outstretched hand) and repetitive stress (running on hard surfaces) are the usual causes.
What a Bone Bruise Feels Like
The hallmark symptom is pain that feels deeper and more intense than a regular bruise. A skin bruise is tender when you press on it. A bone bruise produces a dull, throbbing ache that seems to come from inside the bone itself. Other common symptoms include tenderness directly over the bone, swelling in the surrounding area, and sometimes visible skin discoloration.
The pain often worsens with specific movements or positions. A bone bruise in the knee, for instance, may flare when you stand, walk, or bend the joint under load. The discomfort can be surprisingly persistent, lasting weeks or months after the initial injury, which catches many people off guard when they expect a “bruise” to heal quickly.
How Bone Bruises Are Diagnosed
Standard X-rays will look completely normal because the bone’s outer shell is intact. MRI is the only reliable way to detect a bone contusion. On MRI, damaged marrow appears dark on one type of image (T1-weighted) and bright on another (T2-weighted) because of the increased water content from bleeding and swelling inside the bone. No visible fracture line is present, which is what distinguishes a contusion from a true break.
Doctors typically order an MRI when someone has persistent bone pain after trauma but clean X-rays. The scan also reveals whether the bruise sits near a joint surface, deep within the bone’s interior, or alongside other injuries like torn ligaments or damaged cartilage.
Recovery Takes Longer Than You’d Expect
Bone bruises heal slowly. A study published in the American Journal of Roentgenology tracked patients with knee bone bruises and found a median healing time of 42 weeks, roughly 10 months. Nearly 23% of lesions were still visible on MRI after a full year of follow-up. This is dramatically longer than the one to three weeks most people associate with a regular bruise.
Pain and functional symptoms usually improve well before the MRI findings disappear. Many people feel significantly better within a few weeks to a couple of months, even though the bone is still remodeling internally. The gap between feeling better and being fully healed is important: returning to high-impact activity too early can re-injure the area or slow recovery.
Treatment is almost always conservative. Rest, ice, and avoiding activities that load the injured bone are the foundation. Depending on the location and severity, your doctor may recommend crutches or a brace to limit weight-bearing for a period. Gradual return to activity is guided by pain levels and, in some cases, follow-up imaging.
The Link to Long-Term Joint Damage
When a bone bruise occurs just beneath a joint surface (in the subchondral bone), it can have consequences that outlast the bruise itself. Research in Sports Health found that subchondral bone bruising at the time of a ligament injury can lead to loss of the cartilage that cushions the joint, with measurable cartilage thinning observed more than two years after the original injury.
The mechanism is straightforward but hard to reverse. When the bruised subchondral bone heals, it sometimes forms callus tissue that is stiffer than normal bone. This stiffer foundation absorbs less shock, forcing the cartilage layer above it to take on more compressive force than it was designed for. Over time, that extra stress accelerates cartilage wear and raises the risk of osteoarthritis.
The severity of the initial bone bruise matters. Patients with larger areas of bone marrow swelling at baseline tend to lose more cartilage over the following two years and face a higher likelihood of needing joint replacement down the line. In one analysis, patients with osteoarthritis who also had bone marrow swelling were nearly nine times more likely to need a knee replacement within three years compared to those with osteoarthritis alone. A more widespread pattern of swelling pushed that risk even higher, to about 13 times more likely.
This doesn’t mean every bone bruise leads to arthritis. Small contusions in otherwise healthy joints often heal without lasting consequences. But bone bruises near joint surfaces, particularly large ones or those paired with ligament tears, deserve careful follow-up and a patient approach to returning to full activity.