Is avascular necrosis (AVN) of the lunate bone the same as necrosis of the lunate bone?

Avascular Necrosis of the Lunate is the Same as Necrosis of the Lunate

Yes, avascular necrosis (AVN) of the lunate is the same as necrosis of the lunate, as both terms refer to bone death due to inadequate vascular supply. 1

Terminology and Definition

• Osteonecrosis (bone death due to inadequate vascular supply) is sometimes called "avascular necrosis" or "aseptic necrosis" when involving epiphyseal locations like the lunate bone 1
• When specifically affecting the lunate bone in the wrist, this condition is commonly known as Kienböck's disease 2, 3
• The terms are used interchangeably in medical literature to describe the same pathological process of bone death in the lunate 3

Pathophysiology

• Three possible mechanisms have been proposed for osteonecrosis/avascular necrosis:

  1. Vascular interruption
  2. Vascular occlusion
  3. Extravascular intraosseous compression (often from lipid hypertrophy) 1

• In the lunate specifically, the condition may result from:

  • Traumatic injury disrupting blood supply 2
  • Anatomical variations (such as negative ulnar variance) 2, 3
  • Mechanical factors in genetically predisposed individuals 3

Clinical Presentation and Diagnosis

• Early diagnosis is critical as untreated avascular necrosis leads to progressive collapse of the lunate and derangement of carpal architecture 4
• Physical examination may be indistinguishable from a simple wrist sprain in early stages 4
• Diagnostic imaging progression:
  • Standard radiographs may be normal in early stages 4
  • MRI is the key diagnostic method for early detection, showing high contrast between necrotic and normal bone 4
  • Arthro-MRI can identify underlying ligamentous injuries that may contribute to the condition 2
  • CT scans can provide additional information in cases of traumatic etiology 2

Common Sites and Risk Factors

• The lunate is one of the common sites for osteonecrosis, along with the femoral head, humeral head, scaphoid, and talus 1
• Risk factors for osteonecrosis in general include:
  • Trauma (either isolated or repeated) 2, 3
  • Corticosteroid therapy 1
  • Alcohol use 1
  • Blood dyscrasias 1
  • Prior dialysis in transplant patients 1

Clinical Implications

• Without proper treatment, avascular necrosis of the lunate can lead to:

  • Progressive collapse of the bone 4
  • Chronic wrist pain and disability 5
  • Decreased range of motion and grip strength 5
  • Secondary osteoarthritis 1

• Early diagnosis and treatment can prevent progression of necrotic lesions and bone collapse 2

• Conservative treatment may include immobilization and physical modalities 5

• Surgical intervention may be necessary in advanced cases 5

Important Clinical Distinction

• While avascular necrosis of the lunate (Kienböck's disease) is well-established, a similar but rarer condition can affect the scaphoid bone (Preiser's disease) 6
• Both conditions represent the same pathological process (osteonecrosis) but affect different carpal bones 6