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The triangular fibrocartilage complex (TFCC) is an area in the wrist that is composed of cartilage and fibers with a shape similar to an isosceles triangle. The TFCC is analogous to the ligaments holding the kneecap in place over the knee joint; on a smaller scale, the TFCC holds the radioulnar disk in place at the wrist joint to help protect the joint during movement. Unlike the mid-positioned kneecap ligaments, the TFCC is located mainly along the outside of the wrist, though it can similarly develop instability, tearing, and pain, which can be due to traumatic injury or degenerative processes.
This area allows the wrist to move or bend in six directions. For example, the TFCC makes it possible to twist the wrist or to move the hand from side to side. The TFCC also helps protect the hand and wrist area from impact injuries, since the cartilage and fibers act as a buffer to the bones in this area.
The wrist area contains eight bones, called the carpal bones. The triangular fibrocartilage complex connects the forearm bone of the ulna to two of the hand bones along the outer side of the wrist, which allows the entire structure to move as a unit. This connection enables the wrist to move smoothly and evenly throughout its motions, as well as helps to stabilize the wrist joint during activity.
The wrist joint is one of the most complex and frequently used joints in the human body, and the triangular fibrocartilage complex is the fulcrum of wrist bending activity. The mechanics of wrist activity have been described by bone and joint specialists as involving the transfer of load weights from the lower arm bones to the hand. The weights that are distributed over the wrist and hand through the triangular fibrocartilage complex are sometimes quite forceful, such as the force used while playing tennis or similar activities.
Force affecting the wrist area is cushioned by the radioulnar disk, which is made of hardened cartilage similar to the meniscus. When the force upon this area is greater than the TFCC can handle, however, injuries such as tears can develop. Falls upon the hand can also cause tearing of the triangular fibrocartilage complex.
The triangular fibrocartilage complex can also develop what is known as “degenerative tears.” These can develop with repeated motions of a similar type over the course of a period of time. Aging has been felt to increase the likelihood of this type of injury, since tissues, including ligaments, tend to become thinner and less viable during aging. An inherited anatomical variation in forearm bone lengths has also been felt to predispose toward injuries of the TFCC.
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