Imaging of Osteoarthritis

Osteoarthritis (OA) is the most prevalent joint disorder in the elderly, and there is no effective treatment. Imaging is essential for evaluating the synovial joint structures (including cartilage, meniscus, subchondral bone marrow and synovium) for diagnosis, prognosis, and follow-up. This article describes the roles and limitations of both conventional radiography and magnetic resonance (MR) imaging, and considers the use of other modalities (eg, ultrasonography, nuclear medicine, computed tomography [CT], and CT/MR arthrography) in clinical practice and OA research. The emphasis throughout is on OA of the knee. This article emphasizes research developments and literature evidence published since 2008

Subchondral bone remodeling patterns in larger animal models of meniscal injuries inducing knee osteoarthritis - a systematic review

Purpose Elucidating subchondral bone remodeling in preclinical models of traumatic meniscus injury may address clinically relevant questions about determinants of knee osteoarthritis (OA). Methods Studies on subchondral bone remodeling in larger animal models applying meniscal injuries as standardizing entity were systematically analyzed. Of the identifed 5367 papers reporting total or partial meniscectomy, meniscal transection or destabilization, 0.4% (in guinea pigs, rabbits, dogs, minipigs, sheep) remained eligible. Results Only early or mid-term time points were available. Larger joint sizes allow reporting higher topographical details. The most frequently reported parameters were BV/TV (61%), BMD (41%), osteophytes (41%) and subchondral bone plate thickness (39%). Subchondral bone plate microstructure is not comprehensively, subarticular spongiosa microstructure is well characterized. The subarticular spongiosa is altered shortly before the subchondral bone plate. These early changes involve degradation of subarticular trabecular elements, reduction of their number, loss of bone volume and reduced mineralization. Soon thereafter, the previously normal subchondral bone plate becomes thicker. Its porosity frst increases, then decreases. Conclusion The specifc human topographical pattern of a thinner subchondral bone plate in the region below both menisci is present solely in the larger species (partly in rabbits), but absent in rodents, an important fact to consider when designing animal studies examining subchondral consequences of meniscus damage. Large animal models are capable of providing high topographical detail, suggesting that they may represent suitable study systems refecting the clinical complexities. For advanced OA, signifcant gaps of knowledge exist. Future investigations assessing the subchondral bone in a standardized fashion are warranted

Influence of traumatic impaction and pathological loading on knee menisci

Nearly half of the US population faces the risk of developing knee osteoarthritis (OA). Both in vitro and in vivo studies can aid in a better understanding of the etiology, progression, and advancement of this debilitating disorder. The knee menisci are fibrocartilagenous structures that aid in the distribution of load, attenuation of shock, alignment and lubrication of the knee. Little is known about the biochemical and morphological changes associated with knee menisci following altered loading and traumatic impaction, and investigations are needed to further elucidate how degradation of this soft tissue advances over time. The biochemical response of porcine meniscal explants was investigated following a single bout of dynamic compression with and without the treatment of the pharmaceutical drug, anakinra (IL-1RA). Dynamic loading led to a strain-dependent response in both anabolic and catabolic gene expression of meniscal explants. By inhibiting the Interleukin-1 pathway with IL-1RA, a marked decrease in several catabolic molecules was found. From these studies, future developments in OA treatments may be developed. The implementation of an in vivo animal model contributes to the understanding of how the knee joint behaves as a whole. A novel closed-joint in vivo model that induces anterior cruciate ligament (ACL) rupture has been developed to better understand how traumatic injury leads to OA. The menisci of knees from three different groups (healthy, ACL transected, and traumatically impacted) were characterized using histomorphometry. The acute and chronic changes within the knee following traumatic impaction were investigated. The works presented in this dissertation have focused on the characterization, implementation, and development of mechanically-induced changes to the knee menisci

The human meniscus: transplantation, characterisation and tissue engineering

The Human Meniscus: Transplantation, Characterization and Tissue Engineering Peter Verdonk, MD, PhD; Ghent University, Belgium Abstract The meniscus plays an important role in the complex biomechanics of the knee joint. Removal of this tissue can result in dysfunction and pain in the involved joint compartment and ultimately osteoarthritis. We report on the surgical technique, the clinical and radiological outcome after substitution of the human meniscus with a viable allograft. The results of this type of surgery are encouraging and long-lasting in a well-selected patient population who suffered a total meniscectomy. Viable meniscus allograft transplantation significantly reduces pain and improves function. This beneficial effect remains present in around 70% of the patients at 10 years after surgery. In light of the higher number of partial meniscectomies in the clinical office, further attention was paid to develop tissue engineering strategies to restore and regenerate meniscus tissue without the intrinsic drawback of the use of allogeneic material. A first study aimed at the characterization of the human meniscus cell associated matrix (CAM) synthesis and turnover in two different culture conditions. The alginate culture conditions appear to favor the fibrochondrocyte meniscus cells with a CAM rich in type I collagen and aggrecan and lower quantities of type II collagen, while monolayer cultured meniscus cells have considerable amounts of type I and II collagen but almost no aggrecan in their CAM. Additional investigations led to the description of a new cell-type within the superficial layer of the normal meniscus; the CD34+ meniscus cell. In a second study, we demonstrated that human bone marrow derived mesenchymal stem cells in combination with a type I collagen scaffold have a fibrochondrogenic differentiation potential. This cell-scaffold combination is implantable and could easily deliver autologous hBMSC with meniscus repair potential to the defect. The ultimate goal of meniscus transplantation and tissue engineering is to prevent the degenerative process induced by a partial or total meniscectomy and inflicted upon the articular cartilage. Therefore, metabolic pathways (IGF-1, IL-1, IL-1RII) were investigated in the articular chondrocyte that could be targeted by specific pharmaceuticals (polysulphated cyclodextrines) in order to upregulate an anabolic effect. The use of these substances could improve the results of meniscus substitution procedures in secondary osteoarthritic knee joints