Pathophysiology and risk factors for osteonecrosis

Area of Science:

• Orthopedics
• Pathophysiology
• Bone Biology

Background:

• Osteonecrosis, or avascular necrosis (AVN), is characterized by bone cell death and a complex repair process.
• The resorptive phase of repair, not necrosis itself, causes structural failure and subchondral fracture.
• Compromised subchondral microcirculation is a likely common pathway in AVN pathogenesis.

Purpose of the Study:

• To review the etiologic relationships and pathophysiology of osteonecrosis.
• To understand the mechanisms leading to decreased femoral head blood flow.
• To highlight therapeutic implications based on risk factors and pathophysiology.

Main Methods:

• Emphasis on etiologic relationships from longitudinal cohort studies and meta-analyses.
• Analysis of mechanisms causing decreased femoral head blood flow.
• Review of pathophysiological pathways involving subchondral microcirculation.

Main Results:

• Decreased femoral head blood flow results from vascular interruption, intravascular occlusion, or intraosseous compression.
• Lipocyte hypertrophy and Gaucher cells contribute to intraosseous extravascular compression.
• Longitudinal studies and meta-analyses provide confidence in causal relationships.

Conclusions:

• Understanding AVN pathophysiology, particularly compromised microcirculation, is crucial.
• Etiologic factors influencing femoral head blood flow are identifiable.
• Knowledge of risk factors and pathophysiology informs therapeutic strategies to preserve the subchondral bone.