Dead bone is bone tissue that has died because its blood supply was cut off. The medical term is osteonecrosis (literally “bone death”), also called avascular necrosis. Without steady blood flow, bone cells starve, the internal structure weakens, and tiny fractures develop. Over time, the affected bone can collapse entirely, damaging the joint above it. The condition most commonly strikes the hip, but it can also affect the knee, shoulder, ankle, and jaw.
How Bone Dies
Bone is living tissue that depends on a network of small blood vessels to deliver oxygen and nutrients. When something blocks or damages those vessels, the bone cells in the affected area begin to die within hours. At first the damage is invisible on standard X-rays, and you may feel only a vague ache or nothing at all. As dead cells accumulate and the body’s repair process falls behind, the bone’s internal scaffolding weakens. Small cracks form beneath the joint surface, and if the process continues unchecked, the overlying cartilage loses its support and the bone collapses inward.
What Causes It
The causes split into two broad categories: traumatic and non-traumatic. A broken hip or a dislocated joint can physically tear blood vessels, cutting off flow to part of the bone almost instantly. This sudden disruption is the leading cause of osteonecrosis after an injury.
Non-traumatic cases are more common overall, and two culprits dominate. Alcohol abuse and corticosteroid medications together account for up to 80% of non-traumatic cases. Alcohol appears as a risk factor in roughly 20 to 45% of people with the condition. Corticosteroids, the anti-inflammatory drugs prescribed for conditions like lupus, asthma, and organ transplants, are responsible for another 3 to 40% of non-traumatic cases depending on the population studied. One large study from China found alcohol was the single most common cause (about 38%), followed by steroid use (27%) and trauma (16%).
Other, less frequent causes include radiation therapy, decompression sickness (the “bends” in divers), sickle cell disease, and certain antiretroviral medications used to treat HIV.
Where It Happens Most Often
The hip is the most well-known site because the ball-shaped top of the thighbone (the femoral head) has a particularly vulnerable blood supply. But osteonecrosis can appear in multiple joints at once, especially in people whose bone death is linked to corticosteroid use. In one 15-year multicenter study of steroid-associated cases, the knee was the most common site of involvement. The shoulder, ankle, and small bones of the wrist and foot are also affected in some cases.
A Special Case: Dead Bone in the Jaw
A distinct form of bone death can occur in the jawbone, most often in people taking bisphosphonates, a class of drugs used to treat osteoporosis and certain cancers that have spread to bone. These medications work by slowing down the cells that normally break down and rebuild bone. That’s useful for strengthening a fragile skeleton, but it also means the jaw has a harder time healing after dental work, infection, or trauma. The lower jaw is affected twice as often as the upper jaw.
Dental problems significantly raise the risk. Gum disease nearly triples the odds, and tooth extractions are the triggering event in about a third of cases. Deep cavities, fractured teeth, and poorly fitting dentures also contribute. Roughly another third of jaw cases arise spontaneously, with no clear dental trigger.
Symptoms and How They Progress
In the earliest stage, many people feel no pain at all or notice only a dull ache in the groin, thigh, or the area around the affected joint. This stage is invisible on regular X-rays, which is one reason the condition often goes undiagnosed until it has advanced.
As damage progresses, the pain becomes more consistent and worsens with weight-bearing activity. X-rays begin to show abnormal density in the bone, along with small cysts or patches of increased porosity. In later stages, the bone surface starts to flatten and lose its normal round contour. A characteristic “crescent sign,” a thin line of separation just beneath the joint surface, signals that the bone is beginning to collapse. Once collapse occurs, the joint above becomes painful, stiff, and progressively harder to move.
How It’s Diagnosed
Standard X-rays are the usual first step because they’re inexpensive and widely available. They’re reliable for identifying the later stages of bone death, when structural changes are already visible. The problem is that X-rays lack sensitivity in the early stages, when intervention has the best chance of working.
MRI is considered the gold standard for early detection, with a sensitivity above 99%. It can pick up changes in the bone marrow, including swelling and early scarring, long before any structural collapse shows up on an X-ray. If your doctor suspects osteonecrosis based on your risk factors and symptoms but your X-ray looks normal, an MRI is the next logical step.
Treatment Options
Treatment depends heavily on how far the bone death has progressed when it’s caught. In the earliest stage, a procedure called core decompression can be effective. The surgeon drills into the affected bone to relieve internal pressure, which helps restore blood flow and reduces pain. Think of it like releasing pressure from a swollen compartment. On its own, core decompression relieves pain but doesn’t regenerate bone, so it’s typically combined with some form of bone grafting.
One approach uses a piece of bone from the patient’s own pelvis, still attached to its blood vessels, and transplants it into the drilled-out channel. This living graft serves three purposes: it takes over the job of supporting the joint surface, it fills the space left by dead tissue, and its intact blood supply helps new bone grow in. Recovery involves several weeks of bed rest, followed by non-weight-bearing movement on crutches for about 10 weeks, with full weight-bearing typically allowed after 14 to 16 weeks.
Success rates drop sharply with each stage of progression. In the earliest stage, core decompression prevents the need for further surgery about 84% of the time. By the second stage, that number falls to 63%. By the third stage, when the bone surface has already started to collapse, only about 29% of patients avoid additional surgery. This steep decline is the strongest argument for early diagnosis.
When the bone has already collapsed and the joint is severely damaged, joint replacement surgery becomes the primary option. For the hip, this means a total hip replacement, one of the most successful orthopedic procedures performed today but still a major surgery with a lengthy recovery.
Why Early Detection Matters
The central challenge with dead bone is that the early stages are silent. Pain is mild or absent, and standard X-rays look normal. By the time symptoms become hard to ignore, the bone may already be collapsing, and the window for joint-preserving treatment has narrowed considerably. If you have significant risk factors, particularly long-term corticosteroid use or heavy alcohol consumption, persistent joint pain that worsens with activity warrants investigation even if an X-ray comes back clean. An MRI can catch what X-rays miss, and catching it early is the difference between a minimally invasive procedure and a joint replacement.