The knee is the joint between the femur (thigh bone) and the tibial (lower leg). In front of the knee joint is the patella (kneecap), a bone set in the tendon of the big quadriceps muscle which straightens the leg. Knee fractures are injuries to one or more of these bones close to the knee […]
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What is Anterior Cruciate Ligament tear? The anterior cruciate ligament, or ACL, is one of four major knee ligaments. The ACL is critical to knee stability, and people who injure their ACL often complain of symptoms of their knee giving-out from under them. Therefore, many patients who sustain an ACL tear opt to have surgical […] Histology Understanding the structure and architecture of skeletal muscle begins at the level of the muscle cell, or fiber, itself. Muscle fibers are multinucleated cells with a cylindrical shape, and they have diameters ranging between 10 to 100 µm. Fibers range a few millimeters to several centimeters in length. This wide variation in muscle fiber […] It generally is agreed that intrinsic healing of cartilage lesions does not occur. There may be a response of the chondrocyte to injury, but this response does not result in cartilage repair. The obvious example is seen in degenerative arthritis [degenerative joint disease (DJD) osteoarthrosis, and osteoarthritis (OA)], in which chondrocytes often form clones of […] As noted earlier in the air-tent analogy, the inflation medium of articular cartilage is synovial fluid, which essentially is an ultrafiltrate of plasma plus hyaluronan. The hyaluronan molecules are too large to enter cartilage through its surface pores (diameter, 6 nm), but most of the remaining ions and molecules of normal synovial fluid, such as […] Small proteoglycan molecules consisting of biglycan, decorin, and fibromodulin represent approximately 5% of the proteoglycan of articular cartilage. Dermatan sulfate proteoglycans were first observed in articular cartilage by Rosenberg in 1985. The small proteoglycans each consist of a protein core and glycosaminoglycan chain branches. The core protein of the small proteoglycans is only one fourth […] Sulfated proteoglycan macromolecules constitute 12% of articular cartilage dry weight. The proteoglycans of articular cartilage serve as the “pump” of the highly pressurized cartilage system. As mentioned earlier, the characteristics of the proteoglycan molecules that permit this crucial function include their very large size and resulting immobility within the collagen fibril meshwork; their densely concentrated, […] The molecular structure of collagen has been of considerable interest for more than a century, because it is the principal structural protein (by mass) for all mammals. It constitutes 65% to 80% of the mass by dry weight of such specialized connective tissues as tendons, ligaments, skin, joint capsules, and cartilage. It is the only […] Key Points Few mechanical devices even remotely approach the durability and efficiency of cartilage. The typical response to cartilage injury in which the subchondral plate is fractured is the formation of fibrocartilage, a scarlike tissue unsuited to the support of compressive loads and shear forces. The pattern of collagen fibrils within articular cartilage is well […] |
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