Abstract The knowledge of local stress distribution in hand joints is crucial to understand injuries and osteoarthritis occurrence. However, determining cartilage contact stresses remains a challenge, requiring numerical models including both accurate anatomical components and realistic tendon force actuation. Contact forces in finger joints have frequently been calculated but little data is available on joint contact pressures. This study aimed to develop and assess a hybrid biomechanical model of the index finger to estimate in-vivo joint contact pressure during a static maximal strength pinch grip task. A finite element model including bones, cartilage, tendons, and ligaments was developed, with tendon force transmission based on a tendon-pulley system. This model was driven by realistic tendon forces estimated from a musculoskeletal model and motion capture data for six subjects. The hybrid model outputs agreed well with the experimental measurement of fingertip forces and literature data on the physiological distribution of tendon forces through the index finger. Mean contact pressures were 6.9 ± 2.7 MPa, 6.2 ± 1.0 MPa and 7.2 ± 1.3 MPa for distal, proximal interphalangeal and metacarpophalangeal joints, respectively. Two subjects had higher mean contact pressure in the distal joint than in the other two joints, suggesting a mechanical cause for the prevalence of osteoarthritis in the index distal joint. The inter-subject variability in joint contact pressure could be explained by different neuromuscular strategies employed for the task. This first application of an effective hybrid model to the index finger is promising for estimating hand joint stresses under daily grip tasks and simulating surgical procedures.

中文翻译：

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使用混合有限元肌肉骨骼方法估计食指关节接触压力

摘要 手关节局部应力分布的知识对于了解损伤和骨关节炎的发生至关重要。然而，确定软骨接触应力仍然是一个挑战，需要包括准确解剖组件和真实肌腱力驱动的数值模型。经常计算手指关节中的接触力，但很少有关于关节接触压力的数据。本研究旨在开发和评估食指的混合生物力学模型，以估计静态最大强度捏握任务期间的体内关节接触压力。开发了包括骨骼、软骨、肌腱和韧带的有限元模型，肌腱力传输基于肌腱-滑轮系统。该模型由根据六名受试者的肌肉骨骼模型和动作捕捉数据估计的真实肌腱力驱动。混合模型输出与指尖力的实验测量和关于通过食指的肌腱力的生理分布的文献数据非常吻合。远端、近端指间关节和掌指关节的平均接触压力分别为 6.9 ± 2.7 MPa、6.2 ± 1.0 MPa 和 7.2 ± 1.3 MPa。两名受试者在远端关节的平均接触压力高于其他两个关节，这表明指数远端关节中骨关节炎的流行存在机械原因。关节接触压力的受试者间变异性可以通过用于该任务的不同神经肌肉策略来解释。