ABSTRACT
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. ＜br> OBJECTIVE:To explore periprosthetic stress and bone mineral density and to analyze their correlation after total knee arthroplasty. ＜br> 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. ＜br> 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.
ABSTRACT
Objective To evaluate the clinical efficacy of circumferential ablation at orifice of pulmonary veins with ultrasound energy in the cure of paroxysmal atrial fibrillation(PAF).Methods The study group included 5 patients with PAF who had significant symptom and were drug resistance,and ultrasound ablation was applied at the orifice of their pulmonary veins to get electrical isolation.Results Nineteen pulmonary veins got electrical isolation and among them 3 were combined with radiofrequency ablation.PAF recurred in one patients and atrial premature beats occurred in other two patients but all disappeared after being treated with amiodarone.During the ablation atrial perforation occurred in one patients and severity vague response in another patient.All patients reached a minimum of six months of follow up,and remained in sinus rhythm.Conclusions The circumferential ablation at orifice of pulmonary veins with ultrasound energy is effective in restoration and maintenance of sinus rhythm in patients with PAF.