Avascular necrosis of the femoral head

Disease Description (Causes and Symptoms)

• Definition: Avascular necrosis of the femoral head (AVN of femoral head) is a disease in which reduced or blocked blood flow to the femoral head causes bone tissue to die, followed by femoral head collapse and damage to the articular cartilage, ultimately resulting in hip arthropathy.
• Pathophysiology: Impaired blood flow → necrosis of bone cells and bone matrix → weakening of the bone structure and subchondral fracture → femoral head collapse → cartilage damage and secondary arthritis. It occurs bilaterally in approximately 60% of cases.
• Major causes (risk factors): Excessive alcohol consumption, high-dose or long-term use of adrenocortical hormones (steroids) (alcohol use and steroid use account for a substantial proportion of all causes), trauma (hip fracture/dislocation), diving under high pressure (decompression sickness), hyperlipidemia, gout, chronic kidney disease, chronic pancreatitis, immunosuppressive treatment after transplantation, and others. In some cases, the cause is unknown and the condition is idiopathic.
• Clinical symptoms: In the early stage, there may be no symptoms or mild groin or buttock pain. As the disease progresses, pain increases when walking, limping may occur, and pain when sitting cross-legged may limit posture. When the femoral head collapses, leg shortening and restricted movement may occur.
• Diagnostic features: Early X-rays may be normal, while MRI is the most sensitive method for early diagnosis and is excellent for determining the location and extent of the lesion. Bone scans (nuclear medicine) may show early abnormalities, but their accuracy is lower than that of MRI.

Treatment Methods (Standard Treatment, Medication, Procedures/Surgery, Lifestyle Management and Precautions)

• Conservative management (observation): Follow-up observation is appropriate when the lesion is small, symptoms are mild, or daily activities are not significantly affected. Pain control (analgesics and nonsteroidal anti-inflammatory drugs) and limiting weight-bearing (using crutches, etc.) may slow progression.
• Decompression surgery (core decompression, etc.): Performed mainly in young patients before femoral head collapse, with the aim of lowering intraosseous pressure, relieving pain, and promoting restoration of blood flow. It includes core decompression, multiple drilling, and combinations with bone grafting. Injection of autologous bone marrow or bone marrow-derived stem cells has been attempted, but long-term evidence is limited.
• Regenerative and corrective surgery (osteotomy, etc.): Procedures such as rotational osteotomy attempt to preserve the femoral head by moving the necrotic area to a region subject to less weight-bearing. They may be used in young patients and at relatively early stages, but outcomes are poorer when the lesion is larger.
• Joint replacement (total hip arthroplasty, THA): The standard treatment for advanced femoral head collapse, extensive necrosis, or older patients. It provides the most reliable symptom improvement, but the lifespan of the artificial joint and the possibility of revision surgery must be considered.
• Medication (adjunctive): The use of bone resorption inhibitors (bisphosphonates), anticoagulants, vasodilators, and other medications is under study, and consistent standard benefits have not been established.
• Lifestyle management and prevention: Abstain from alcohol, minimize steroid use (adjust the dose and duration when possible), manage hyperlipidemia and underlying diseases, control weight, and avoid activities that place excessive impact on the joints.
• Precautions and complications: Early diagnosis and treatment are important, as untreated disease can progress from femoral head collapse → severe arthritis → permanent loss of function. Be aware of surgery-related complications (infection, thrombosis, and surgical failure), the possibility of revision surgery, and wear or dislocation of the artificial joint.

Checklist Before an Outpatient Visit (Consultation)

• Items to bring
  • List of medications currently being taken (including steroids), along with records of recent medications, doses, and durations
  • Alcohol use (frequency and amount) and smoking status
  • History of previous surgery or trauma (especially involving the hip), and history of transplantation or immunosuppressive treatment
  • CDs or reports of previous imaging tests (recent X-rays, MRI, and bone scans)
  • Results of relevant blood tests (lipids, liver and kidney function, etc.) and tests for underlying diseases
• Symptom records
  • Location of pain (including whether it radiates to the groin, buttock, or knee), pain intensity (quantified), onset, and progression
  • Activities that worsen or relieve the pain (walking, using stairs, sitting, etc.)
  • Limitations in daily activities (sitting cross-legged, climbing stairs, weight-bearing, etc.)
• Other
  • Recent weight changes and occupational or sports activities (activities that place stress on the knees or hips)
• Standard recommendation before requesting useful outpatient tests
  • If early progression is suspected, MRI is recommended as the priority test (for early detection). Bringing the results of X-rays and bone scans as well can help establish a diagnosis and treatment plan.

Examples of General Questions to Ask the Doctor

• "How advanced is my lesion (based on staging criteria such as MRI)?"
• "Is improvement possible with conservative treatment? What are the criteria for recommending surgery?"
• "Between decompression surgery and joint replacement, which treatment is recommended in my situation, and why?"
• "If I undergo surgery, what will the recovery period and rehabilitation schedule be like (including when weight-bearing will be allowed)?"
• "What are the side effects of this medication (the prescribed painkiller or other medication)?"
• "How likely is recurrence or involvement of the other hip in the future?"

Examples of Disease-Specific Questions

• "Please tell me the area of the necrotic lesion on MRI (expressed as a percentage) and its location (including the weight-bearing area), and explain whether this size and location meet the indications for decompression surgery or osteotomy."
• "Given my current condition, what conservative measures (weight-bearing restrictions, physical therapy, medication, etc.) are recommended to delay joint replacement as much as possible, and what are their expected effects and duration?"