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[Pathological anatomy of femur head necrosis]
1Institut für Pathologie, Universität Basel.
Abstract:
Aseptic necrosis of the femoral head appears to have a number of etiological factors. The last steps of the pathogenetic course of events, however, is unclear. Histologically, small foci of marrow necrosis form repeatedly, particularly in the upper and medial zone of charge, and then fuse secondarily to larger areas. Secondary reparation events with ingrowth of sprouts of granulation tissue and neoformation of bone predominantly in connection with necrotic trabeculi are followed by renewed waves of necrosis, resulting in a most variegated picture in which the different phases can no longer be clearly differentiated. After the articular cartilage has been sequestrated and torn away, the uncovered spongious bone is exposed to the transforming influence of direct charge, with subsequent secondary osteoarthrosis. From the histological picture follows the modern conception of its pathogenesis: an intraosseous increase in pressure primarily infringes on the venous outflow and secondarily on the arterial inflow. These cyclic circulatory disturbances provoke the focal appearance of necrosis. As a result of this, "core decompression" follows as a therapeutic intervention that is successful in many cases.
Insights
Aseptic necrosis of the femoral head involves repeated marrow necrosis and repair cycles. Increased intraosseous pressure disrupting circulation is the key pathogenesis, often treatable with core decompression.
Area of Science:
- Orthopedics
- Pathology
- Vascular Biology
Context:
- Aseptic necrosis of the femoral head (ANFH) has multiple causes, but the precise pathogenetic mechanisms remain incompletely understood.
- Histological examination reveals recurring small foci of marrow necrosis, particularly in the superior and medial aspects of the femoral head.
- These necrotic areas coalesce, and subsequent repair attempts with granulation tissue ingrowth are often overwhelmed by further necrotic waves.
Purpose:
- To elucidate the detailed pathogenetic process of aseptic necrosis of the femoral head.
- To correlate histological findings with the proposed mechanism of intraosseous pressure changes.
- To provide a basis for understanding the efficacy of therapeutic interventions like core decompression.
Summary:
- Histologically, ANFH is characterized by repeated focal marrow necrosis and subsequent attempts at repair, leading to a complex, heterogeneous pathological picture.
- The articular cartilage can be compromised, leading to exposed subchondral bone and the development of secondary osteoarthrosis.
- The prevailing theory suggests that increased intraosseous pressure initially impairs venous outflow, subsequently affecting arterial inflow, causing cyclic circulatory disturbances and focal necrosis.
Impact:
- Understanding the pathogenesis of ANFH is crucial for developing effective treatment strategies.
- The proposed mechanism of increased intraosseous pressure provides a rationale for surgical interventions.
- Core decompression, aimed at reducing intraosseous pressure, has demonstrated success in managing ANFH in numerous cases.