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.%背景:骨水泥固定型人工关节假体骨腔内的植入必然涉及受区骨髓腔的长期闭塞和髓内血管的破坏,由此而产生的髓内压和血流的变化是材料本身的影响所致,很有研究价值.目的:观察骨水泥阻塞兔股骨近中段骨干髓腔后远侧骨干骨内压和骨血流的改变.设计:对照观察.单位:广西壮族自治区人民医院.材料:实验于2002-07/2003-04在重庆医科大学实验动物中心完成.选用32只健康成年新西兰大白兔,随机摸球法取24只为模型组,其余8只不造模,作为对照组.聚甲基丙烯酸甲酯TJ骨水泥由天津市合成材料工业研究所提供.方法:模型组采用兔左侧股骨髓腔内灌注骨水泥进行造模.采用髋后外方入路,从股骨后外方肌间隙进入,在第3转子上方仅切除大转子外侧部分而不打断股骨颈,暴露转子间窝,找到骨髓腔入口,扩髓(深度为股骨长度的1/2),反复冲洗创面,冲出破坏的骨髓组织,沙布条沾干.按粉、液比2:1比例调配骨水泥,首先将一小块面团状骨水泥作为髓腔塞填入髓腔内至股骨中段狭窄处,待10 min骨水泥基本固化后,继续填入调配好里面团状骨水泥,直至填满为止.待骨水泥完全固化后,缝合关闭切口.将24只模型组兔再根据不同的观察时间段随机分成术后当天、4,8,16周4个时间点,每时间点6只.主要观察指标:①使用生理测压仪,测量对照组和模型组术后不同时间点动物双侧股骨远端骨内压,并进行比较.②采用核素骨显像方法,对模型组术后不同时间点动物双侧股骨远端动态和静态显像进行检测和比较.结果:32只兔均进入结果分析,无脱失.①骨内压:正常兔股骨远端双侧骨内压差异不显著(P＞0.05):各时间点实验侧骨内压高于对照侧(P＜0.01).模型组对照侧不同时间点比较差异均不显著(P＞0.05),实验侧处于持续骨内高压状态,术后4周高于术后16周(P＜0.05),其他时间点比较差异不显著(P＞0.05).②核素骨显像:术后当天及术后4周实验侧核素计数均比对照侧明显降低,术后8,16周实验侧均超过对照侧,术后16周最高:各时间段实验侧,对照侧核素计数比值中除术后当天及术后4周比较差异不显著外其他时间点两两比较差异显著(P＜0.05).核素骨动态和静态显像的变化趋势完全一致.结论:骨水泥阻塞股骨近中段骨干髓腔后严重破坏了骨内和髓内的血液循环状态,引起了局部血流动力学的改变,导致股骨远端的骨内压和骨血流发生了一系列的变化,使骨内压持续升高并长期存在.
展开▼
