In this paper, we propose a method to estimate the parameters of a double hinge model of the trapeziometacarpal joint (TMC) by MRI-based motion analysis. The model includes two non-orthogonal and non-intersecting rotation axes accounting for flexion-extension (F-E) and adduction-abduction (A-A). We evaluated the quality of the estimated model parameters in the prediction of the relative motion of the first metacarpal bone with respect to the trapezium. As a result, we obtained that: (a) the estimated location and orientation of the F-E and A-A axes were in agreement with previous in vitro studies, (b) the motion of the first metacarpal predicted by the 2 degrees of freedom (2DoF) model exhibits a maximum surface distance error in the range of about 2 mm and (c) four thumb postures at the boundary of the TMC range of motion are sufficient to provide a good estimation of the 2DoF TMC kinematic model and good reproducibility (~1.7 mm) of the real thumb motion at TMC level.
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http://dx.doi.org/10.1080/10255840903260818 | DOI Listing |
Injured epithelial organs must rapidly replace damaged cells to restore barrier integrity and physiological function. In response, injury-born stem cell progeny differentiate faster compared to healthy-born counterparts, yet the mechanisms that pace differentia-tion are unclear. Using the adult Drosophila intestine, we find that injury speeds cell differentiation by altering the lateral inhibition circuit that transduces a fate-determin-ing Notch signal.
View Article and Find Full Text PDFPurpose: Double-level osteotomies (DLOs) have shown promising results for knee joint preservation, however, most ultimately progress in terms of degenerative disease resulting in conversion to total knee arthroplasty (TKA). Therefore, the purpose of this study was to examine the time to TKA conversion, long-term clinical outcomes and revision rates of patients who have undergone TKA after prior ipsilateral DLO.
Methods: Patients who underwent simultaneous or staged DLO and subsequently underwent conversion to TKA at a single academic institution from 1997 to 2022 were evaluated.
Osteotomies around the knee have a variety of indications, including pain reduction, functional improvement, knee joint stabilization, and articular cartilage preservation. Thorough preoperative planning is essential, including a determination of the precise location of any deformity (proximal tibia, distal femur, or both). High tibial osteotomies and distal femoral osteotomies can be performed in isolation, or jointly in the form of a double-level osteotomy, for correction of coronal and/or sagittal deformity of the knee.
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January 2025
Department of Medicine I, Agaplesion Markus Hospital, Goethe University, Frankfurt, Germany.
Sci Rep
December 2024
School of mines, China University of Mining and Technology, Xuzhou, 221000, China.
As the core component of a swivel bridge, the spherical hinge structure exhibits complex mechanical behavior under high pressure, making it challenging to describe accurately through theoretical analysis or on-site monitoring. In this context, this paper systematically examined the mechanical characteristics and key design parameters of a simplified spherical hinge structure using numerical simulations and formula derivation. Additionally, an indoor scaled test was conducted based on a representative spherical hinge structure to further investigate its mechanical properties.
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