An immunohistochemical study of the triangular fibrocartilage complex of the wrist: regional variations in cartilage phenotype

Abstract

The triangular fibrocartilage complex (TFCC) transmits load from the wrist to the ulna and stabilizes the distal radioulnar joint. Damage to it is a major cause of wrist pain. Although its basic structure is well established, little is known of its molecular composition. We have analysed the immunohistochemical labelling pattern of the extracellular matrix of the articular disc and the meniscal homologue of the TFCC in nine elderly individuals (age range 69 -96 years), using a panel of monoclonal antibodies directed against collagens, glycosaminoglycans, proteoglycans and cartilage oligomeric matrix protein (COMP). Although many of the molecules (types I, III and VI collagen, chondroitin 4 sulphate, dermatan sulphate and keratan sulphate, the oversulphated epitope of chondroitin 6 sulphate, versican and COMP) were found in all parts of the TFCC, aggrecan, link protein and type II collagen were restricted to the articular disc and to entheses. They were thus not a feature of the meniscal homologue. The shift in tissue phenotype within the TFCC, from a fibrocartilaginous articular disc to a more fibrous meniscal homologue, correlates with biomechanical data suggesting that the radial region is stiff and subject to considerable stress concentration. The presence of aggrecan, link protein and type II collagen in the articular disc could explain why the TFCC is destroyed in rheumatoid arthritis, given that it has been suggested that autoimmunity to these antigens results in the destruction of articular cartilage. The differential distribution of aggrecan within the TFCC is likely to be reflected by regional differences in water content and mobility on the radial and ulnar side. This needs to be taken into account in the design of improved MRI protocols for visualizing this ulnocarpal complex of the wrist.

Gene Expression Differences Between Ruptured Anterior Cruciate Ligaments in Young Male and Female Subjects

“…The ACAN gene encodes aggrecan, an important proteoglycan molecule within the extracellular matrix of ligaments and many other musculoskeletal tissues; most importantly, aggrecan is a major structural component of human cartilage and fibrocartilage [18][19][20][21] . Aggrecan is a large, aggregating proteoglycan that plays a critical role in mediating chondrocytechondrocyte and chondrocyte-matrix interactions.…”

Assessment of T1, T1ρ, and T2 values of the ulnocarpal disc in healthy subjects at 3 tesla

“…The changes comprise reduced cellularity, loss of elastic fibers, mucoid degeneration of the ground substance, exposure of collagen fibers, fibrillation, erosion, ulceration, abnormal thinning, and, ultimately, disc perforation. An immunohistochemical study of the TFCC [8] in nine elderly individuals demonstrated that the ulnocarpal disc is a fibrocartilaginous structure which labels for type II collagen and aggregan, a proteoglycan-typical marker of a cartilaginous phenotype, whereas the meniscal homologue of the TFCC is a more fibrous structure. …”

The location-specific role of proteoglycans in the flexor carpi ulnaris tendon

“…As a result, its insertion angle is not physically constrained and it experiences multiaxial loading during in vivo loading [15]. In particular, during wrist adduction, a joint motion partially controlled by the FCU muscle, the FCU tendon-pisiform enthesis is subject to high shear strains that have been linked to a fibrocartilage-like structure and composition in other tendons [16, 17]. Interestingly, the FCU insertion site is known to contain high levels of collagen II and aggrecan, a large proteoglycan typically associated with cartilaginous tissues that experience predominantly compression and shear [15].…”