Browsing by Subject "Ligament"

Now showing 1 - 3 of 3
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    Connexins and pannexins in the skeleton: gap junctions, hemichannels and more
    (Springer, 2015-08) Plotkin, Lilian I.; Stains, Joseph P.; Department of Anatomy & Cell Biology, IU School of Medicine
    Regulation of bone homeostasis depends on the concerted actions of bone-forming osteoblasts and bone-resorbing osteoclasts, controlled by osteocytes, cells derived from osteoblasts surrounded by bone matrix. The control of differentiation, viability and function of bone cells relies on the presence of connexins. Connexin43 regulates the expression of genes required for osteoblast and osteoclast differentiation directly or by changing the levels of osteocytic genes, and connexin45 may oppose connexin43 actions in osteoblastic cells. Connexin37 is required for osteoclast differentiation and its deletion results in increased bone mass. Less is known on the role of connexins in cartilage, ligaments and tendons. Connexin43, connexin45, connexin32, connexin46 and connexin29 are expressed in chondrocytes, while connexin43 and connexin32 are expressed in ligaments and tendons. Similarly, although the expression of pannexin1, pannexin2 and pannexin3 has been demonstrated in bone and cartilage cells, their function in these tissues is not fully understood.
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    Magic Angle Effect on Diffusion Tensor Imaging in Ligament and Brain
    (Elsevier, 2022) Wang, Nian; Wen, Qiuting; Maharjan, Surendra; Mirando, Anthony J.; Qi, Yi; Hilton, Matthew J.; Spritzer, Charles E.; Radiology and Imaging Sciences, School of Medicine
    Purpose: To evaluate the magic angle effect on diffusion tensor imaging (DTI) measurements in rat ligaments and mouse brains. Methods: Three rat knee joints and three mouse brains were scanned at 9.4 T using a modified 3D diffusion-weighted spin echo pulse sequence with the isotropic spatial resolution of 45 μm. The b value was 1000 s/mm2 for rat knee and 4000 s/mm2 for mouse brain. DTI model was used to investigate the quantitative metrics at different orientations with respect to the main magnetic field. The collagen fiber structure of the ligament was validated with polarized light microscopy (PLM) imaging. Results: The signal intensity, signal-to-noise ratio (SNR), and DTI metrics in the ligament were strongly dependent on the collagen fiber orientation with respect to the main magnetic field from both simulation and actual MRI scans. The variation of fractional anisotropy (FA) was about ~32%, and the variation of mean diffusivity (MD) was ~11%. These findings were further validated with the numerical simulation at different SNRs (~10.0 to 86.0). Compared to the ligament, the DTI metrics showed little orientation dependence in mouse brains. Conclusion: Magic angle effect plays an important role in DTI measurements in the highly ordered collagen-rich tissues, while MD showed less orientation dependence than FA.
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    Use of an Abductor Pollicis Brevis Tendon Slip for Reconstruction of the Radial Collateral Ligament of the Thumb Metacarpophalangeal Joint: An Anatomical Investigation
    (Sage, 2023) Schmidt, Gregory J.; Crosby, Nicholas E.; Merrell, Gregory A.; Graduate Medical Education, School of Medicine
    Background: Reconstruction of the radial collateral ligament (RCL) of the thumb metacarpophalangeal (MP) joint is commonly performed for chronic injuries. This study aims to evaluate the anatomical feasibility and reliability of using the abductor pollicis brevis (APB) tendon to reconstruct the RCL. Methods: Ten cadaver arms were dissected to evaluate the relationship between insertions of the RCL and APB. A slip of the APB was divided from tendon and reflected proximally. The dissected tendon was deemed sufficient for reconstruction if it could be reflected to the footprint of the RCL origin. The size of the dissected APB slip was then compared with that of the RCL. Results: The dissected slip of the APB could be fully reflected proximally to the RCL origin in all specimens. The APB insertion was also found to be closely approximated to the RCL insertion, averaging 2.1 mm distal and 1.8 mm dorsal. Significant differences existed between the lengths (P < .001) of the APB slip and RCL, with no significant difference in widths (P = .051). Conclusions: A sufficient APB tendon slip can be obtained to reliably reconstruct the RCL of the thumb MP. The location of the APB insertion closely approximates the RCL insertion.