BACKGROUND:At present, the incidence rates of knee joint diseases such as knee osteoarthritis, knee joint degenerative are high. The major clinical treatment is total knee replacement in the clinic, so it is necessary to evaluate the changes in stress and bone mineral density of the regions surrounding the prosthesis after replacement. OBJECTIVE:To explore periprosthetic stress and bone mineral density and to analyze their correlation after total knee arthroplasty. METHODS:A total of 20 cases undergoing total knee arthroplasty were chosen.The hospital for special surgery scores were used to evaluate patients’ functional recovery at 12 months after total knee arthroplasty. The periprosthetic femur was divided into four regions of interest (ROI), respectively ROI 1-4;periprosthetic tibia was divided into three regions of interest, respectively ROI 5-7. Stress surrounding the prosthesis was analyzed using three-dimensional finite element analysis at 1, 3, 6 months, 1, 2, 3 years after replacement. Simultaneously, bone mineral density surrounding the prosthesis was measured using dual-energy X-ray absorptiometry. RESULTS AND CONCLUSION:No patients affected infection or loosening of the prosthesis. At 12 months after replacement, the score of hospital for special surgery was (90.23±2.37), which showed significant differences as compared with before replacement (39.68±1.31) (P<0.05). The level of stress shielding was highest in ROI 5 and lowest in ROI 3. Stress shielding rate of ROI increased with statistical difference at 6 months after operation (P<0.05). At 1, 2, 3 years after operation, shielding rate in periprosthetic femoral stress in ROI 1 decreased. Compared with 1 month after operation, the difference was statistical y significant (P<0.05). However, shielding rate of tibial periprosthetic stress in ROI 6 increased. Compared with 1 month after operation, the difference was statistical y significant (P<0.05). Bone mineral density after 1 month after operation had no significant decrease (P>0.05). At 3 months after operation, bone mineral density began to decline significantly (P<0.01). The decrease was most obviously in ROI 5 and the change was least in ROI 3. After 1 year of operation, bone mineral density did not change significantly. These data indicated that changes in bone mineral density were correlated with stress shielding after total knee arthroplasty. Monitoring two variations can provide theoretical data for preventing bone loss, which provides references for clinical rehabilitation guidance.%背景：目前膝骨关节炎、膝关节退行性等膝关节病变发病率较高，临床上主要的治疗手段是全膝关节置换，因此有必要对置换后假体周围应力及骨密度变化进行评估。 目的：观察全膝关节置换后假体周围应力，并连续监测骨密度变化，分析二者之间的相关性。 方法：选择全膝关节置换后患者20例，置换后12个月应用美国特种外科医院膝关节评分对患者的功能恢复情况进行评估。将股骨假体周围分为4个兴趣区，分别为ROI 1-4区；胫骨假体周围分为3个兴趣区，分别为ROI 5-7区。应用三维有限元方法分别在置换后1，3，6个月，置换后1，2，3年分析膝关节假体周围应力变化；同时应用双能X射线骨密度仪测量膝关节假体周围骨密度。 结果与结论：所有患者均未发生感染或假体松动，置换后12个月美国特种外科医院膝关节评分为(90.23±2.37)分，与置换前(39.68±1.31)分比较，差异有显著性意义(P <0.05)。ROI 5区应力遮挡最明显，ROI 3区应力遮挡最少。置换后6个月，ROI各分区的应力遮挡率增高，差异有显著性意义(P<0.05)。置换后1，2，3年，股骨假体周围ROI 1区应力遮挡率减小，与置换后1个月比较，差异有显著性意义(P<0.05)；而胫骨假体周围6区应力遮挡率增加，与置换后1个月比较，差异有显著性意义(P<0.05)。膝关节假体周围骨密度在置换后1个月时无明显下降(P>0.05)，置换后3个月开始明显下降(P<0.01)，且以ROI 5区最明显，而ROI 3区变化较小。置换1年以后，骨密度变化不明显。提示全膝关节置换后假体周围骨密度变化与其应力遮挡存在相关性，监测二者变化，可为预防骨质流失提供理论数据，并为临床康复指导提供参考依据。
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