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A member of the Pilon Fractures Facebook group posted the other day about finding possible avascular necrosis on an X-ray seven months after his initial break. Now, his doctor is talking about an ankle fusion surgery.
As of January 2025, I am also seven months post-ORIF (and two months post-bone graft), and still, my X-rays show nonunion. Of course, I want to give the bone graft more time to do its thing—perhaps that will help with healing as intended—but Gareth's question got me more curious about possible causes of nonunion.
Osteonecrosis, also known as avascular necrosis (AVN) or aseptic necrosis, is the death of bone cells due to decreased blood flow.
If diagnosed early, treatment options may include medications for pain relief or activity limitation, while advanced osteonecrosis usually requires surgical intervention.
Osteonecrosis occurs when the blood supply to a part of a bone is disrupted.
Osteonecrosis can be caused by injuries that damage nearby blood vessels.
Bone fractures are common causes of traumatic osteonecrosis. Insufficiency fractures (or stress fractures) can also be associated with osteonecrosis.
For pilon fracture patients, research suggests that the risk of osteonecrosis is largely determined by the mechanical and structural damage caused by the fracture (severity, location, open vs. closed fracture) rather than by inherent traits or health status (age, sex, underlying medical conditions, weight).
High-dose corticosteroids like prednisone are another cause of avascular necrosis because they can increase lipid levels and reduce blood flow.
Long-term use of bisphosphonates (medications used to increase bone density) may contribute to osteonecrosis in the jaw.
Some medical treatments, like chemotherapy or radiation, can also increase the risk of osteonecrosis by damaging blood vessels.
Excessive alcohol use is a risk factor for osteonecrosis. It can lead to the accumulation of fatty substances in blood vessels. Increased cortisol from too much alcohol could also contribute to the narrowing of blood vessels.
Research about the influence of cigarette smoking on osteonecrosis of the femoral head (ONFH) shows that too much tobacco use could also be a risk factor.
Sickle cell disease, lupus, and myeloproliferative disorders can disrupt the blood supply to the bones.
Patients with HIV are often seen with osteonecrosis because of the antiretroviral medications used for their treatment.
Other medical conditions linked to osteonecrosis are Caisson disease, Crohn's disease, arterial embolism, thrombosis, vasculitis, kidney disease, liver disease, osteoporosis, and gout.
At first, osteonecrosis may not show any symptoms. However, as it gets worse, you might start to feel pain, especially in your weight-bearing bones.
Osteonecrosis can occur in the middle of a bone, such as the shaft of the tibia, though it is less common than in joints. Blood supply is more vulnerable in the joints (e.g., hips, knees, or ankles) because these areas have higher mechanical stress, and end arteries supply them.
Symptoms of osteonecrosis in tibial pilon fractures include persistent pain, swelling, reduced range of motion, and difficulty bearing weight, often worsening over time.
Some descriptions I read on Reddit about how avascular necrosis feels include:
The period between symptoms starting and loss of function seems to be different for each person and could range from a few weeks to more than a year.
Early diagnosis of osteonecrosis through imaging tests can help stop disease progression and preserve joint function before arthritis develops.
Magnetic Resonance Imaging (MRI) is a highly sensitive tool that can detect early signs of necrosis of bone before it is visible on X-rays. They can also show the extent of the bone damage.
X-rays can reveal changes in bone structure in later stages but may appear normal early on. In the later stages of osteonecrosis, X-rays are often used to monitor the condition and may reveal characteristic signs such as a "crescent sign."
Weight-bearing X-rays can help doctors understand how stable and strong your bones and joints are. These X-rays can show early signs of joint collapse or misalignment when under stress, which might not be visible in non-weight-bearing images. If you think a weight-bearing X-ray might be helpful, you can ask your doctor if they have the right equipment to do one. However, in the early stages of osteonecrosis, X-rays might not show any changes, so MRI scans may be more helpful here.
A CT scan can provide clearer images than X-rays, but it is less commonly used than MRI due to its lower sensitivity.
Bone cells that have died cannot come back to life, but the surrounding bone tissue can regenerate under the right conditions if the blood supply is restored.
Early-stage disease may heal on its own with nonsurgical treatments. However, in most cases, surgery is eventually required. If the disease progresses, a joint replacement might be necessary.
Dead bone tissue can be replaced by healthy bone through bone remodeling, the natural process by which old or damaged bone is replaced with new, healthy bone.
If a bone does not remodel on its own, you may need surgical interventions like core decompression, bone grafting, or vascularized bone grafting to make a framework for new bone growth. Surgical options are used when nonsurgical methods fail or the disease worsens.
If the surgical options listed above don't resolve nonunion or osteonecrosis, you may need revision surgery to get additional bone grafting or advanced fixation.
For extreme situations where the damage is irreparable, options like external fixation, long-term pain management, or even below-the-knee amputation may be considered.
Emerging therapies like stem cell treatments or hyperbaric oxygen therapy could also promote bone regeneration.
Some other possible causes of nonunion in tibial pilon fractures could be:
I continue to be curious about what might be causing my nonunion. So far, my healthcare team has mostly said, "It's just bad luck," but seven months is a long time to keep battling this mentally in addition to physical.
Given the conversation in the Pilon Fracture Facebook Group, I will be asking my doctor about avascular necrosis and to test my blood supply because the other reasons seem unlikely to me at this point.
