ABSTRACT
BACKGROUND: Total knee arthroplasty surgery (TKA) using prenavigated Patient Specific Instruments (PSI) technique represents one of the most recent technological evolutions in development of prosthetic surgery. The aim of this study was to evaluate kinematic and functional recovery of patients operated with prenavigated PSI technique compared to those operated with traditional technique. METHODS: A cohort of 20 patients is divided in two groups; some are operated with traditional technique (with NexGen Knee system) and others with prenavigated PSI technique (with eMP Knee system) at Asiago Hospital. Limb circumferences are measured for edema evaluation and different evaluation forms are provided to patients: SF-36, KSS pre-surgery (T0), KSS 15 (T1) and 45 days after surgery (T2). Gait Analysis is performed 60 days post-surgery, after leaving crutches. RESULTS: The analysis of KSS and SF-36 evaluation forms shows a greater improvement in PSI Evolution group in terms of articulation (comparison between T0 and T1), knee function and early return to physical and social activities. Pain is lesser in NexGen group, in an earlier phase, but 45 days after surgery (T2) there are no significant differences between two groups. Perception of general state of health improves more and earlier in NexGen. In NexGen group edema evaluation had significant differences at the level of prosthetic leg, but not in knee and thigh. Overall: the walking pattern is more physiological in PSI Evolution group. CONCLUSIONS: The present study highlighted the superiority of prenavigated PSI technique over traditional technique in recovering functionality of prosthetic knee and in restoring a more physiological path pattern.
ABSTRACT
The chemical Langevin equation and the associated chemical Fokker-Planck equation are well-known continuous approximations of the discrete stochastic evolution of reaction networks. In this work, we show that these approximations suffer from a physical inconsistency, namely, the presence of nonphysical probability currents at the thermal equilibrium even for closed and fully detailed-balanced kinetic schemes. An illustration is given for a model case.
ABSTRACT
In this work, we deal with general reactive systems involving N species and M elementary reactions under applicability of the mass-action law. Starting from the dynamic variables introduced in two previous works [P. Nicolini and D. Frezzato, J. Chem. Phys. 138(23), 234101 (2013); 138(23), 234102 (2013)], we turn to a new representation in which the system state is specified in a (N × M)(2)-dimensional space by a point whose coordinates have physical dimension of inverse-of-time. By adopting hyper-spherical coordinates (a set of dimensionless "angular" variables and a single "radial" one with physical dimension of inverse-of-time) and by examining the properties of their evolution law both formally and numerically on model kinetic schemes, we show that the system evolves towards the equilibrium as being attracted by a sequence of fixed subspaces (one at a time) each associated with a compact domain of the concentration space. Thus, we point out that also for general non-linear kinetics there exist fixed "objects" on the global scale, although they are conceived in such an abstract and extended space. Moreover, we propose a link between the persistence of the belonging of a trajectory to such subspaces and the closeness to the slow manifold which would be perceived by looking at the bundling of the trajectories in the concentration space.
