In this paper, we study the initial value problem for the fractional differential equation with multiple deviating arguments. By using Krasnoselskii’s fixed point theorem, the conditions of solvability of the problem are obtained. Furthermore, we establish Ulam–Hyers and generalized Ulam–Hyers stability of the fractional functional differential problem. Finally, two examples are presented to illustrate our results, one is with a pantograph-type equation and the other is numerical.

Wear is the third most important factor that restricts the longevity of total knee replacements (TKRs). Wear is particularly influenced by load, local kinematics between the contact surfaces and presumably by the geometry of the contact surfaces. This article investigated, by means of multibody models, how wear in total knee replacements is affected by the size of a TKR or by TKR-related geometric parameters during gait motion. As a result, it has been established that wear rate increases linearly as a function of TKR size, while the impact of TKR-related geometric parameters can be described by linear or quadratic functions. One can conclude that the newly introduced dimensionless parameters can provide guidelines to effectively minimize wear in TKRs.

The connection between running experience and running-related injuries is still unclear, and the underlying mechanisms are yet to be fully investigated. Therefore, this study aimed to investigate differences in ground reaction forces (GRFs) between novice runners and recreational runners. 15 novice and 15 recreational runners participated in this study. An independent samples T-test was applied using SPSS 25.0 and SPM1D via Matlab. The results showed that recreational runners exhibited a significantly larger peak vertical impact force and peak medial force than the novice group, while the peak propulsive force was smaller than the novice group. The SPM1D results also showed that recreational runners and novice runners exhibited significant differences in medial-lateral force, anterior-posterior force and vertical force. The differences between the groups may reveal differences in running kinetics, which could be related to superior running performance or ability. Valuable insights may be gained from this study to guide future research on injury risks and performance benefits from running.