| The orbit is an anatomic space located in the foreside of the face. The degree of exophthalmos is in a normal range because of the bilateral symmetry of orbital cavity. Most of enophthalmos are due to the decreased orbital soft-tissue or enlarged orbital cavity. Biological materials are used to pad into the orbit to correct enophthalmos, but sometimes the operation will be defeated as materials are rejected or infected. Diplopia appears in some patients with orbital fracture because of incarceration and adhesion of extraocular muscles. Although the incarceration of muscle can be resovlved by operation, there has not found the efficient way to the muscle adhesion.Autologous fat transplantation has been used in surgery for over 100 years. Fat tissue is an ideal material because of minimal tissue reaction and easy availability. Dermis-fat grafts and fat particles are applied by ophthalmologists to correct socket deformities,sunken upper eyelid,winkle et al. However, it has not been reported that free-fat grafts was transplanted into orbits .Rabbits were chosen as animal models. Because only a little fat tissue were found in Tenons's capsule of rabbit orbit and the2001superior lateral quadrant of rabbit orbit was expans , it is convenient to observe free-fat grafts .Subject:Volume measurement,Computer tomograph (CT ) scan,histologic and ultrastructure examination were made to observe the change of autogenous free-fat grafts used in orbital transplantation in order to discuss the transplantation rules and survival machnisms of free-fat grafting by which to provide the theoretic evidence for clinical applications.Method:The study was performed on 18 adult rabbits divided 3 groups. 1ml free-fat grafts taken from groin fat pad were implanted in the superior lateral quadrant of rabbit orbit. The volume were measured at 1 2, 3month after implantion. Evaluation was made by computed tomograph ( CT) scan, light microscope and electronic microscope observation.Result:1: The volume of free-fat grafts decreased obviously at the first month after implantation, decreased average 40.83%; The volume reduced average 50.97% at the third month .2: CT showed that an irregular density mass in the donor site at the first month after implantation, a mostly low density and a2001little high density at the second month and a regular low density mass at the third month.3: The grafed fat ischemia, adipocytes necrosis, cystlike cavities, inflammatory cell, osinophilic cell and preadipocytes were seen by histological observation at the first month; The preadipocytes differentiated to mature adipocytes after revasculation. Fatty lobule formed partly and cystlike cavities, inflammatory cell, eosinophilic cell decreased obviously at the second month; The structure of grafted fat was almost normal at the third months.4: Histomorphometric analysis revealed that the mean cell area of normal fat was 93.17%. After implantation, the mean fat cell area was 42.41% at the first month; 69.74% at the second month and 85.55% that near to the normal fat cell area at the third month.5: Active adipocytes precursors and preadipocytes were found by ultrastructural study at the first month after implantation. The new formation mature adipocytes and still adipocytes precursors were found at the third month.Conclusion:The autogenous free-fat grafts were survival steadily at the third month after implantation, the grafts volume suvived about200150%. Histology displayed that the structure of grafted fat was almost normal at the third month. CT showed the density variety of fat grafts similar to the histological observation, so fat grafts survival could be proved by CT. Ultrastructural study revealed that preadipocytes different to the mature fat cell. In conclusion, it is credible that orbital transplantation with autogenous free-fat grafts can be used to correct orbital soft tissue defects and adhesion of extraocular muscle in theory. |
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