Intravasation of fat from the bone marrow cavity

Area of Science:

• Orthopedics
• Radiology
• Pathology

Background:

• Fat embolism syndrome (FES) is a serious complication following long bone fractures.
• The precise mechanism of fat intravasation from marrow into circulation remains incompletely understood.

Purpose of the Study:

• To investigate the dynamics of fat intravasation from tibial marrow cavities into circulation.
• To determine the incidence and extent of pulmonary fat embolism following marrow fat injection.
• To evaluate the effect of tibial fractures on fat intravasation and pulmonary deposition.

Main Methods:

• Labeled fat (triolein-(131)I) was injected into tibial marrow cavities in animal models.
• Radioactivity was monitored in the thorax and various organs post-injection.
• Histological methods confirmed the presence of pulmonary embolic fat; intravasation pressure was measured.

Main Results:

• Significant amounts of injected fat (mean 44.8%) were detected in the lungs, indicating pulmonary fat embolism.
• A substantial portion of fat remained in the injected tibia (mean 44.7%).
• Tibial fractures significantly reduced the amount of fat found in the lungs compared to intact tibias.

Conclusions:

• Intravasation of marrow fat can lead to pulmonary fat embolism.
• Tibial fractures appear to mitigate the severity of pulmonary fat embolism.
• Elevated pressure within the marrow cavity can rapidly induce fat embolism.