Influence of cartilage thickness on impulsive stress in interphalangeal joints

Fracture-dislocation of proximal interphalangeal (PIP) joints caused by impact loadings is one of the common injuries in finger joints. The influence of thickness of articular cartilage on the impulsive stress in PIP joints is studied using the dynamic finite element method in the present paper. As the thickness of cartilage decreases, the concentration of equivalent stress is observed in the cartilage. The maximum principal stress is tension in the subchondral bone of the middle phalanx and does not change much with the thickness of cartilage. The thin cartilage layer causes the decrease of the minimum principal stress in the subchondral bone and consequently leads to the concentration of equivalent stress. The influence becomes remarkable when the thickness is reduced to a quarter of normal thickness, indicating that the risk of failure is higher when the cartilage has worn out.