Bone Marrow Edema - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Edema is a health problem where fluid builds up in the body's tissues, causing swelling and discomfort. It can affect various body parts, including the legs, arms, hands, feet, and internal organs. Edema is often a symptom of any medical condition or injury. It can also be a side effect of certain medications or prolonged periods of immobility.

What Is Bone Marrow Edema?

Bone marrow edema is characterized by the accumulation of excess fluid in the bone marrow. This condition, also known as bone marrow lesion, is often associated with pain, swelling, and reduced joint function. While bone marrow edema can occur in various body parts, it is commonly found in the knee, hip, and ankle joints. Since the introduction of MRI in clinical practice, bone marrow lesions (BMLs) have become a significant aspect of various musculoskeletal conditions, both inflammatory and non-inflammatory.

Initially referred to as bone marrow edema (BME) due to water signals on MRI, later histological examinations revealed that most cases did not exhibit edematous changes at the tissue level. Consequently, the term bone marrow lesion was adopted. Numerous studies have linked the presence of BMLs to pain and disease progression, prompting the exploration of treatment modalities to alleviate pain and slow disease advancement.

What Causes Bone Marrow Edema?

The development of bone marrow edema can be due to several factors.

Traumatic Causes

• Various fractures (acute, osteoporotic, and stress fractures).

• Changes in stress or biomechanics (such as plantar fasciitis, tendinitis).

• Bone contusions (bone bruises).

• Osteochondral injuries, including osteochondritis dissecans.

• Transient local osteoporosis.

Degenerative Conditions

• Osteoarthritis affects joints like the hip, knee, and others

• Modic lesions, specifically in the spine.

Inflammatory Factors.

• Inflammatory arthropathies and enthesitis, such as rheumatoid arthritis (RA), ankylosing spondylitis, and psoriasis.

• Systemic chronic inflammation leading to fibrosis.

Neoplastic and Neoplastic-Like Conditions

• Acute myeloid leukemia.

• Chondrosarcoma.

• Ewing sarcoma.

• Bone metastasis

• Osteosarcoma.

Ischemic Factors

• Avascular necrosis.

• Complex regional pain syndrome (Sudek's atrophy of bone).

• Conditions like sickle cell anemia.

Infections

• Osteomyelitis (bone infection).

• Conditions associated with infections like diabetic foot and Charcot's foot.

• Sepsis-related bone infarcts.

Metabolic and Endocrine Causes

• Hydroxyapatite deposition disease.

• A gout is a form of arthritis caused by the deposition of uric acid crystals.

• Vitamin-D deficiency.

Treatment-Induced Causes

• Surgical interventions.

• Radiotherapy.

• Medications with immunosuppressive effects, including glucocorticoids and Cyclosporin.

• Cytostatics (medications that inhibit cell growth or division).

What Are the Types of Bone Marrow Lesions or Bone Marrow Edema?

Primary Bone Marrow Edema

• Also known as spontaneous BME syndrome.

• Occurs without an apparent underlying cause or trigger.

• It can affect individuals without a history of trauma or known medical conditions.

Secondary Bone Marrow Edema

• Arises as a result of specific underlying conditions or factors.

• It can be associated with various diseases and medical specialties.

• Often, it requires identifying and addressing the primary condition for effective treatment.

What Are the Clinical Features of Bone Marrow Edema?

Common symptoms include:

• Pain is the most prevalent symptom of bone marrow edema. The pain is typically localized to the affected joint or bone and may range from mild to severe.

• Swelling or fluid buildup in the affected area is another common symptom.

• Bone marrow edema can restrict the range of motion in the affected joint. This limitation can make it challenging to perform everyday tasks and activities.

• Stiffness in the affected joint is a frequent complaint.

• In cases of bone marrow edema resulting from inflammation, the skin over the affected area may become red and warm to the touch.

How Is Bone Marrow Edema Diagnosed?

To diagnose bone marrow edema, the following methods are commonly employed:

• Physical Examination - A doctor will conduct a physical examination focusing on the affected joint or bone. They will assess for tenderness, swelling, and any limitations in range of motion.

• X-rays - X-rays are often the first imaging study ordered to assess bone health. While bone marrow edema may not be visible on standard X-rays, they can help identify other bone conditions or fractures contributing to the symptoms.

• Magnetic Resonance Imaging - MRI is the most valuable imaging modality for diagnosing bone marrow edema. It provides detailed images of the soft tissues, including the bone marrow. On an MRI, bone marrow edema appears as areas of increased signal intensity.

• Computed Tomography Scan - CT scans are sometimes used to evaluate bone abnormalities, especially when MRI is not feasible or necessary. CT scans can detect bone fractures and structural issues.

• Bone Scintigraphy - Bone scintigraphy, or a bone scan, involves injecting a small amount of radioactive material into the bloodstream. This material accumulates in areas of increased bone turnover, such as those affected by bone marrow edema. A gamma camera is used to create images of these areas.

• Blood Tests - In some cases, blood tests may be conducted to rule out underlying systemic conditions that could contribute to bone marrow edema, such as autoimmune diseases or infections.

How Is Bone Marrow Edema Treated?

Bone marrow edema usually goes away on its own with time and rest. Treatment includes managing the symptoms and treating any underlying conditions.

The commonly done treatment includes the following.

Physical Therapy

Physical therapy can be beneficial in managing bone marrow edema. Extracorporeal shock wave therapy delivers mechanical shock waves to the bone marrow lesion-affected area. It has shown promise in providing pain relief and functional improvement in hip bone marrow edema cases, potentially by improving blood flow.

Medications

• Nonsteroidal anti-inflammatory drugs are effective in reducing pain and alleviating inflammation in bone marrow edema.

• Corticosteroid injections are sometimes given directly into the affected joint to alleviate symptoms.

• Tumor necrosis factor inhibitors, primarily used for rheumatoid arthritis, reduce BMLs, lower disease activity, and diminish erosions.

• Prostaglandin I2 (prostacyclin) and related analogs boost bone regeneration and microcirculation.

Injections

Platelet-rich plasma and stem cell injections have shown promise in treating bone marrow edema, especially in cases related to osteoarthritis or overuse. These injections promote tissue healing and reduce inflammation.

Surgical Intervention

Surgical intervention may be necessary when other options fail. Commonly performed surgeries include;

• Core decompression involves drilling holes in the area with BME to alleviate pressure, based on the hypothesis of reduced microcirculation causing ischemia and increased intraosseous pressure. It has been used to reduce pain and improve function in conditions like OA. Some variations combine core decompression with bone graft insertion, and others use hydroxyapatite cement injection in areas with BML and osteonecrosis, resulting in pain reduction.

• Core decompression with autologous bone marrow stem cells is employed for treating hip osteonecrosis by increasing the number of committed osteogenic cells in affected areas.

• Efforts have been made to administer autologous and allogeneic stem cells intravenously, yielding mixed outcomes and limited reported complications.

Treating Underlying Conditions

Suppose bone marrow edema results from an underlying condition like rheumatoid arthritis or infection; addressing the primary disease is essential. Managing the underlying condition can help prevent the recurrence of bone marrow edema.

Conclusion

Bone marrow edema involves the accumulation of excess fluid in the bone marrow.As research and medical advancements continue, it is hoped that new treatments and therapies will emerge, further improving the outlook for individuals with bone marrow edema.