| ã€Objective】To explore the short-term and long-term effects of different postoperative treatments on the distal femoral bone blood supply, intraosseous pressure, bone metabolism, bone mineral density and articular structure at different stages after blocking of proximal and middle femoral medullary cavity with bone cement. We hope to provide not only an applicative or preventive theory for the clinical use of cement hip prosthesis but also a simple and effective treatment method for orthopedists.ã€Methods】 1.Animal model establishment: Established the rabbit model whose proximal and middle femoral medullary cavity of left side was infused with PMMA while the right side served as the control. Randomly divided them into 4 groups according to the following different postoperative methods: model control (group A), drilling decompression (group B), normal saline injection (group C) and radix salvia miltiorrhiza injection (group D). Then each group was further divided into 4 subgroups based on the following observational time-points: postoperative 0 day (T0), 4th week (T4), 8th week (T8) and 16th week(T16). The T0 subgroup wastaken as control while testing the bone mineral density.2.Radionuclide bone imaging: Selected and fixed the same interesting regions located in bilateral distal femurs by using 99mTc-MDP during blood flow dynamic and static phases, then compared the nuclide counting ratio of the experimental side (left) to the control side (right).3.Intraosseous pressure measurement: Physiological pressure- measuring instrument was used to detect, analyze and compare the intraosseous pressure of bilateral distal femoral medullary cavity of the experimental and control groups. 4.Bone mineral density measurement: DEXA was used to detect, analyze and compare the bone mineral density of the bilateral distal femurs of the experimental and control groups.5.Pathomorphology: The rabbits was killed to obtain the samples of distal femoral articular synovium, cartilage and the bone under cartilage. Then the structural changes of these tissues were observed by HE staining, toluidine blue staining, immunohistochemistry and transmission electron microscope. Using disulphine blue-vein-infusion method to survey the blood supply changes of the distal femoral cortical bones of the experimental groups.ã€Results】 1.Gross observation: It was proved by sample dissection that the animal model was successfully established to achieve the purpose of using PMMA to block the proximal and middle femoral medullary cavity.2.X-ray: It showed the medullary cavities were well filled with PMMA and completely blocked above their middle segments.3.Radionuclide bone imaging: (1) As for the drilling and non-drilling decompression group on T0, the distal femoral dynamic and static images of experimental sides were all lower than those of the control sides. There wasno significant difference of the nuclide counting ratio of both sides between the 2 groups (P>0.05). (2) Compared the dynamic and static images with same postoperative treatment at different time-points: those of the experimental sides of group A and C were lower than the controls at T4 while higher at T8 and T16 (T8 was the highest). There was no statistical significance of the nuclide counting ratio between T0 and T8, T0 and T16, T4 and T16, T8 and T16, T4 and T8, respectively (P<0.05) except T0 and T4 (P>0.05); in group B and D, the images of the experimental sides were all higher than those of the controls at T4, T8 and T16 (T8 was the highest). There was significant difference of the nuclide counting ratio between T0 and T4, T0 and T8, T0 and T16 (P<0.05) except T4 and T16, T8 and T16, T4 and T8 (P>0.05). 4. Intraosseous pressure measurement: (1) There was no statistical difference of the intraosseous pressure between the distal femurs in normal rabbits (P>0.05); on T0, the pressure of the experimental side increased notably and statistical difference existed between bilateral sides (P<0.05); on T4, T8 and T16, the same sides of group A...
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