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BACKGROUND: Implantation of artificial joint of bone cement can result in long-term blocking of recipient site medullary canal and blood vessel lesion, and lead to changes in intraosseous pressure and bone blood flow of distal femoral shaft.OBJECTIVE: To explore the changes in the intraosseous pressure and bone blood flow of distal femoral shaft after blockage of the proximal and middle femoral medullary canal by bone cement.DESIGN: Controlled observation.SETTING: People's Hospital of Guangxi Zhuang Autonomous Region.MATERIALS: The experiment was performed at the Experimental Animal Center of Chongqing Medical University between July 2002 and April 2003. Thirty-two healthy adult New Zealand rabbits were selected and randomly divided into model group (n=24) and control group (n=8). Polymethyl methacrylate (PMMA) TJ bone cement was provided by Tianjin Synthetic Materials Research Institute.METHODS: The rabbit model was established by infusing femoral medullary canal of left side with PMMA. The lateral greater trochanter of anesthetized rabbits were resected below the third trochanter through spatium intermusculare by posterior lateral femur approach, but the neck of femur was remained to expose intertrochanteric fossa and entry of medullary canal following by intramedullary reaming to 1/2 length of femur. The wound was washed repeatedly to remove the destroyed myeioid tissues, and was dried with gauze. Bone cement was prepared by manually stirring powder with solution at a ratio of 2:1, until dough shape formed. A small piece of dough-shaped bone cement was filled in middle femoral stenosis as cavity blocker. Ten minutes later, the solidified bone cement was re-blended until dough shape and implanted into medullary canal fully. When the bone cement was completely solidified, the incision was sutured. The 24-modeled rabbits were randomly divided into 4 subgroups according to the following observation time points (n=6): postoperative 0 day (T0),4th week (T4), 8th week (T8) and 16th week (T16).MAIN OUTCOME MEASURES: ①Physiological pressure-measuring instrument was used to detect and compare the intraosseous pressure of bilateral distal femoral medullary canal of the model and control groups. ②Radionuclide bone imaging was used to detect and compare the dynamic and static images of bilateral distal femoral of the rabbit models at different time points.RESULTS: Thirty-two rabbits were all included in final analysis with no loss. ①There were no significant differences in the intraosseous pressure between the distal femurs in normal rabbits (P＞0.05); the pressure of the experimental side increased significantly compared with control side (P＜0.01). In model group, there were no significant differences in the intraosseous pressure between the control sides of rabbits at different time points (P＞0.05), but the experimental sides presented continuous high intraosseous pressure state. The pressure of T4 was higher than that of T16 (P＜0.05); there were no significant differences between any other two time points (P＞0.05). ②Compared with the dynamic and static images at different time-points, the counting of nuclide in the experimental sides was markedly lower than the control sides at T0 and T4 while higher at T8 and T16; the count reached the peak at T16. There were no significant differences in the nuclide counting ratio between T0 and T8, T0 and T16, T4 and T16, T8 and T16, T4 and T8, respectively except T0 and T4 (P＜0.05). The dynamic and static radionuclide bone imaging showed the same changes.CONCLUSION: The intraosseous and intramedullary blood circulation is severely damaged after blocking of the proximal and middle femoral medullary canal with bone cement, resulting in local alterations of hymodynamics, a series of changes in intraosseous pressure and bone blood flow in the distal femur, which causes continuous and a long-term high intraosseous pressure.
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BACKGROUND:There are so many researches on the complication of artificial joint of bone cement on clinics, but the effect of implanting artificial joint of bone cement on the structure of distal joint is unclear.OBJECTIVE:To explore the structural changes of distal joint after blocking the proximal and middle femoral medullary cavity with bone cement.DESIGN:Controlled observation.SETTING:The People's Hospital of Guangxi Zhuang Autonomous Region.MATERIALS:A total of 26 healthy adult New Zealand rabbits, of clean grade and both genders,weighing 2.6-3.5 kg,were offered by the Experimental Animal Center of Chongqing Medical University.Polymethyl methacrylate (PMMA) TJ bone cement,16# antrum needle for puncture (outer diameter 1.6 mm,inner diameter 1.05 mm,length 80 mm), light microscope of Japan Olympus Company (BH-2), and transmission electron microscope of Japan Hitachi Company (H-600).METHODS:The experiment was completed in the Experimental Animal Center of Chongqing Medical University from July 2005 to April 2006.Eighteen rabbits were randomly selected as model group,while other 8 ones ware served as control group.The rabbit model was established by infusing femoral medullary cavity of left side with PMMA.Due to the specific anatomic structure of appearing the third trochanter, the anesthetized rabbits were adopted to incise the lateral greater trochanter below the third trochanter through spatium intermusculare of posterior lateral femur, remaining the neck of femur, so as to expose intertrochanteric fossa and entry of medullary cavity,which was expanded to 1/2 length of femur by using cavity file of different thickness repeatedly. Then wound surface was washed fob many times to remove the destroyed myeloid tissues, and was dried with strips. Bone cement was prepared by manually stirring powder with solution at a ratio of 2:1, until it demonstrated dough shape. In order to control the depth of bone cement into femoral medullary cavity, a small piece of dough-shaped bone cement was filled in middle femoral stenosis as cavity blocker.Ten minutes later,the solidified bone cement was re-blended as dough shape and implanted into medullary cavity fully.Afterwards, the bone cement was completely solidified and the incision was sutured. At the 4th, 8th and 16th weeks postoperatively,6 rabbits of each model group and all controlled rabbits were killed respectively to obtain the samples of distal femoral articular synovium, cartilage and subchondral bone. The histological examinations included hematoxyiin-eosin (HE) staining, toluidine blue (TB) staining and immunohistochemistry. Transmission electron microscope was used to detect the changes of cartilage and subchondral bone in distal joint of left femur.MAIN OUTCOME MEASURES: ①The structural changes of distal femoral articular synovium, cartilage and subchondral bone by HE staining,TB staining,immunohistochemistry.②The histological changes of distal articular cartilage and subchondral bone in left femur by transmission electron microscope.RESULTS:①HE staining:The damages to articular cartilage,synovial tissues and subchondral bone aggravated with time.At the 16th week of modeling,the articular cartilage was destructed,the bone structure was severely damaged,with the synovial tissue proliferation and swelling;TB staining (the 16th week):All the layers of articular cartilage appeared loss of stain; Immunohistochemistry (the 16th week): Collagen Ⅱ of the chondrocytes was positively stained. And transforming growth factor (TGF)-β1 staining of articular synoviocytes and chondrocytes appeared positive.②Transmission electron microscope: The lesions to articular chondrocytes and bone cells aggravated progressively with time, part of which presented necrosis and collapse at the 16th week.CONCLUSION: The intramedullary blood circulation is severely damaged after blocking the proximal and middle femoral medullary cavity with bone cement. Conversely, the bone metabolism disorders in dista0 femur. which results in the degeneration or necrosis of distal femur, cartilage and synovial tissue.
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BACKGROUND: There are so many researches on complication of artificial joint of bone cement in clinics, but the effect of implanting artificial joint of bone cement on distal femoral shaft is unclear.OBJECTIVE: To provide an ideal animal model for study the effect on distal femoral shaft after implanting the artificial joint of bone cement.DESIGN: Controlled observation.SETTING: People's Hospital in Guangzi Zhuang Autonomous Region.MATERIALS: A total of 16 healthy adult New Zealand rabbits, of clean grade, of both genders, weighing 2.6-3.5 kg, were selected in this study.METHODS: The experiment was completed in the Experimental Animal Centerof Chongqing Medical University from July 2002 to April 2003. According to the third rotator, neck of femur of rabbits was not broken off;meanwhile, lateral part of greater trochanter was sawed up above the third rotator, entrance of medullary cavity of bone was found among fossas of rotator, and bone cement was perfused into left femoral medullary cavity by blocking of proximal and middle femoral medullary cavity with polymethyl methacrylate (PMMA) to establish the rabbit model. Right side of rabbits was regarded as the control. Rabbits were sacrificed under drugged state after modeling establishment.MAIN OUTCOME MEASURES: Results of gross femur and X-ray image of rabbits.RESULTS: A total of 16 rabbits entered the final analysis. ① Gross dissection showed that the femoral medullary cavities of rabbits were well filled with PMMA and completely blocked above their middle segments. It suggested that the method for setting up animal model achieved the purpose of blocking the proximal and middle femoral medullary cavity. ② X-ray image further confirmed that the femoral medullary cavities of rabbits were well filled with PMMA and completely blocked above their middle segments.CONCLUSION: The rabbit model was successfully established by blocking the proximal and middle femoral medullary cavity for imitating the fixed artificial joint of bone cement.
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0.05),the times of operation,hospitalization,leaving sickbed after operation and the healing wound had significant difference in statistics(P