Ratcheting strain and theoretical prediction of articular cartilage under cyclic loading / 医用生物力学

Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.

Ratcheting strain and theoretical prediction of articular cartilage under cyclic loading / 医用生物力学

Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.

Ratcheting strain and theoretical prediction of articular cartilage under cyclic loading / 医用生物力学

Objective To obtain the ratcheting strain of articular cartilage under different loading conditions, and construct the theoretical model so as to predict the ratcheting strain of cartilage. Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject. The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique. The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates. The results from predictions were compared with the experimental results. Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing. The ratcheting strain increased with stress amplitude increasing when the stress rate was constant. However, the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant. When the stress rate increased, the ratcheting stain decreased. The prediction results of the established theoretical model were in good agreement with experimental results. Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude, and inversely proportional to the stress rate. The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.

Ratcheting strain and theoretical prediction of articular cartilage under cyclic loading / 医用生物力学

Objective To obtain the ratcheting strain of articular cartilage under different loading conditions,and construct the theoretical model so as to predict the ratcheting strain of cartilage.Methods The fresh articular cartilage obtained from the trochlear of distal femur was used as experimental subject.The ratcheting strain of articular cartilage was tested under cyclic compressive loads by applying the non-contact digital image correlation technique.The theoretical model was constructed to predict the ratcheting strain of articular cartilage with different stress amplitudes and stress rates.The results from predictions were compared with the experimental results.Results The ratcheting strain of cartilage increased rapidly at initial stage and then showed the slower increase with cycles increasing.The ratcheting strain increased with stress amplitude increasing when the stress rate was constant.However,the ratcheting strain decreased with stress rate increasing when the stress amplitude was constant.When the stress rate increased,the ratcheting stain decreased.The prediction results of the established theoretical model were in good agreement with experimental results.Conclusions The ratcheting strain of articular cartilage is proportional to the stress amplitude,and inversely proportional to the stress rate.The established theoretical model can predict the ratcheting strain of articular cartilage and provide guidance for the construction of tissue engineered artificial cartilage.

Quasi-static and cyclic compressive loading studies of the intervertebral disc with combined flexion and torsion / Estudo da compressão monotônica e cíclica associada à flexão e torção do disco intervertebral

Bovine caudal motion segments were used to investigate the loss of load-bearing ability of the intervertebral disc (IVD) under both quasi-static and cyclic compressive loading combined with torsion and flexion. While the response of the disc to both compressive hyper-flexion and hyper-torsion has been previously investigated much less is known about their individual and combined influence on compressive failure. Eighty motion segments dissected from 41 bovine tails were subjected to quasi-static and cyclic compression with added components of flexion and torsion. The four different combinations of flexion and torsion were 0º torsion/0º flexion, 10º torsion/15º flexion, 10º torsion/0º flexion and 0º torsion/15º flexion. Quasi-static compression failed to show any significant difference among the different combinations of torsion and flexion for failure stress, failure strain and compressive tangent modulus. Cyclic compression indicated a significant influence of torsion in reducing the disc's load-bearing ability. Cyclic loading provides a more sensitive tool for the assessment of potentially damaging mechanical parameters for the IVD.

Segmentos de cauda bovina foram utilizados para investigar a perda de capacidade de suporte de carga do disco intervertebral (IVD) sob compressão monotônica e cíclica combinada com torção e flexão. Embora a resposta do disco a hiper-flexão e hiper-torção compressiva já fora previamente investigada, pouco se conhece sobre suas influências individuais e combinada para a falha compressiva. Oitenta segmentos dissecados a partir de 41 caudas bovina foram submetidos a compressão monotônica e cíclica com componentes adicionais de flexão e de torção. As quatro combinações diferentes de flexão e torção foram 0º torção/0º flexão, 10º torção/15º flexão, 10º torção/0º flexão e 0º torção/15º flexão. A compressão monotônica não evidenciou qualquer diferença significativa entre as diferentes combinações de torção e flexão para tensão de ruptura, deformação em ruptura e módulo tangente. A compressão cíclica indicou influência significativa da torção na redução da capacidade de carga do disco intervertebral. A carga cíclica proporciona uma ferramenta sensível para a avaliação de parâmetros mecânicos potencialmente deletérios ao IVD.

Compression of the intervertebral disc with combined flexion and torsion

Bovine caudal motion segments were used to investigate the loss of load-bearing ability under both quasi-static and cyclic loading. 80 motion segments dissected from 41 bovine tails were subjected to quasi-static and cyclic compression...