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Minimal osteonecrosis as a segmental infarct within the femoral head
1Department of Orthopaedic Surgery, Osaka University Medical School, Japan.
Abstract:
Minimal osteonecrosis (MON) is a small and eccentrically localized lesion of osteonecrosis (ON) of the femoral head. This form of ON shows clinically benign features, but may be indicative of the pathomechanism of ON. Of 180 patients (275 hips) with ON, 15 patients (19 hips) were found to have MON. Based on the geography of the femoral head, the lesions were grouped into four types: anterior (seven hips), superior (six hips), medial (five hips), and lateral (one hip). When the location of the lesion was compared with the normal vascular anatomy, a close correlation between the location and the segmental blood supply in the femoral head became evident. Histologic findings showed localized infarction of the trabeculae and bone marrow, but no evidence suggesting repeated episodes of infarction, which is an essential feature of typical ON. From these findings, MON may be a segmental infarct within the femoral head. Interruption of the blood flow may possibly occur not in the main trunk but in the terminal branch of the lateral epiphyseal or superior metaphyseal artery; such as ischemic event is probably a single brief attack, leading to this form of infarction in contrast to typical ON developing with prolonged or recurrent obstructions.
Insights
Minimal osteonecrosis (MON) is a distinct form of femoral head osteonecrosis (ON). This study suggests MON represents a localized infarct, possibly due to a brief interruption in a terminal artery
Area of Science:
- Orthopedics
- Pathology
- Radiology
Background:
- Minimal osteonecrosis (MON) is a rare, eccentrically located lesion of osteonecrosis (ON) in the femoral head.
- While clinically benign, MON may offer insights into the pathogenesis of ON.
- Understanding MON's unique characteristics is crucial for differentiating it from typical ON.
Purpose of the Study:
- To characterize the anatomical location and vascular correlation of minimal osteonecrosis (MON) in the femoral head.
- To investigate the histopathological features of MON and compare them with typical osteonecrosis.
- To elucidate the potential pathomechanism underlying MON.
Main Methods:
- Retrospective analysis of 180 patients with osteonecrosis (ON), identifying 15 patients (19 hips) with minimal osteonecrosis (MON).
- Classification of MON lesions based on femoral head geography: anterior, superior, medial, and lateral.
- Correlation of lesion location with femoral head vascular anatomy and histopathological examination of MON lesions.
Main Results:
- Minimal osteonecrosis (MON) lesions were categorized into anterior, superior, and medial types based on location.
- A significant correlation was observed between MON lesion location and the segmental blood supply of the femoral head.
- Histology revealed localized bone and bone marrow infarction without evidence of repeated ischemic events, distinguishing MON from typical ON.
Conclusions:
- Minimal osteonecrosis (MON) appears to be a segmental infarct within the femoral head.
- The pathogenesis of MON may involve a single, brief interruption of blood flow in a terminal artery (lateral epiphyseal or superior metaphyseal artery).
- This contrasts with typical osteonecrosis, which is associated with prolonged or recurrent vascular obstructions.