Patient factors influencing preoperative expectations of patients undergoing total knee arthroplasty / 北京大学学报(医学版)

OBJECTIVE@#To investigate the expectations of patients for total knee arthroplasty (TKA), and to analyze its influencing factors.@*METHODS@#Experimental design: Single center, retrospective, multiple regression analysis. The data including the age, height, and weight of 108 patients undergoing unilateral TKA due to end-stage osteoarthritis were obtained. The patients' preoperative Hospital for Special Surgery (HSS) knee arthroplasty expectation score, the Western Ontario and McMaster Universities (WOMAC) score, Knee Society score (KSS), the MOS 36-item short-from health survey (SF-36) score, and visual analogue scale (VAS) were evaluated, and the 30-second chair-stand test (30-CST), 40-meter fast-paced walk test (40-FPWT), 12-level stair-climb test (12-SCT), 3-meter timed up-and-go test (TUG), 6-minute walk test (6-MWT), and recorded daily steps for 7 consecutive days were performed. The SPSS 22.0 software was used for statistical analysis. The observed values of various data were described. Pearson correlation analysis was used to evaluate the correlation between various parameters, and the multi-factor linear regression analysis was used to investigate the influencing factors of the patients preoperative expectation scores.@*RESULTS@#The average expectation score of this group of patients was 58.98±5.44. In the Pearson correlation analysis, the patient's preoperative expectation had a weak correlation to the result of the patient's 12-SCT, TUG, 6-MWT, KSS function score, and SF-36 mental component score (correlation coefficient 0.1-0.3). The patient's preoperative expectation had a moderate correlation to the patient's daily average steps, 30-CST, 40-FPWT, KSS, WOMAC and its pain, stiffness, function scores, SF-36 physical functioning, role-physical, bodily pain, vitality, and physical component score (correlation coefficient 0.3-0.6). In the multivariate linear regression analysis, only the results of 30-CST and the role-physical, bodily pain and vitality in the SF-36 scale were related to the patient's expectation score (P < 0.05).@*CONCLUSION@#The estimated expectation score of patients before TKA is not high. Patients with more severe preoperative pain, worse physical function, and lower overall health are more eager to improve after surgery. Thus surgeons must communicate fully with patients with unrealistic expectations before surgery in order to obtain more satisfactory results postoperatively.

Factors affecting asymmetrical lower extremity loading after unilateral total knee arthroplasty / 医用生物力学

Total knee arthroplasty (TKA) is the most common surgery for treating late-stage knee osteoarthritis. Previous studies have shown that after unilateral TKA, the load-carrying on lower limbs is asymmetrical and the contralateral knee have to bear even greater loads. Therefore, the osteoarthritis side is susceptible to become even worse and under the risk of subsequent replacement. In this review, factors affecting asymmetrical loading on lower limbs, including changes in alignment, pain, muscle weakness, loss of proprioception, and psychological factors are reviewed. The overall effects of these affecting factors on human body, compensation of asymmetrical loading on the body segments and clinical interventions are also discussed. Specific clinical interventions can be introduced to reduce the risk of osteoarthritis or replacement of contralateral knee by analyzing the above factors affecting asymmetrical loading on lower limbs after unilateral TKA.

Individualized selection of total hip prosthesis based on finite element method / 医用生物力学

Objective To investigate ISO 7206 standard used as a guidance for clinical selection of total hip prosthesis. Methods Kinematics and dynamics process of normal walking gait was simulated by establishing a numerical musculoskeletal model; the corresponding finite element model of total hip prosthesis was constructed, and gait loads were applied to calculate stress distribution on prosthesis, which were compared with that on ISO finite element model. ResultsPeaks of hip joint reaction forces were achieved at 20% gait and 54% gait during normal walking gait, which were used as gait loads for finite element simulation, and the results showed that the maximum Von Mises stress of prosthesis was reached at 20% gait. The maximum Von Mises stress of prosthesis in loosening model was higher than that in non-loosening model, and some differences existed in the distribution pattern. The maximum stresses of prosthesis both under ISO loads and gait loads by different body weights were analyzed and compared, and the maximum stress of prosthesis under ISO loads was equivalent to that under gait loads by body weight between 108 kg and 142 kg. ConclusionsThe prosthesis that passed ISO test can meet the strength requirement for normal gait loads of 100 kg body weight.