Microscopic structural changes in osteoarthritic menisci of the human knee joint

Abstract

Background: Osteoarthritis (OA) is a degenerative joint disease for which there is currently no cure. It is characterized by degeneration of articular cartilage and changes in other joint tissues, including subchondral (substance) bone and menisci. It is one of the leading causes of chronic disability. Patients affected by this disease experience pain and loss of function. OA can be caused by a variety of factors, including diet, injury, stress, and genetic abnormalities. However, the molecular mechanisms driving the disease onset and progression are not fully understood. Therefore, this study is undertaken to estimate a large number of human OA menisci for microscopical structural changes in osteoarthritic menisci by histological techniques. Materials and Methods: Medial and lateral osteoarthritic menisci were collected from 110 human knee joints. After collecting the meniscal samples were stored in 10% formalin for 3–5 days. For each meniscus, three separate (anterior, middle, and posterior) parts were processed. The menisci were sectioned in two places vertically at 45° and 135° angles relative to the sagittal plane. After that, each part was sectioned along the horizontal plane from the inner border to the outer border. Then, tissues were fixed in 10% buffered formalin for 24 h. Tissue samples were brought in for routine tissue processing and studied for histological stain with hematoxylin and eosin (H and E) and Alcian blue pH 2.5, to find surface integrity, cellularity, fibrous organization and collagen orientation, and mucoid degeneration. Results: Meniscal degeneration begins with the tissue material rather than the surface. Tissue fibrillation and tears were first observed at the inner border, spread over time to the articular surface of the meniscus, and progressed to complete destruction or loss of meniscal tissue. The left side knee menisci have more OA than the right side. OA cases were more common in both legs, in the age group 60–69 years. Women and Hindus have higher OA cases than men and other religions, respectively. Nonvegetarian and physically inactive individuals were more susceptible to OA, and B +ve and O +ve were more prone to OA than other blood groups. Conclusion: Significant cellular and matrix differences were observed in the meniscus during degeneration. These findings may contribute to further understanding of knee OA and the search for biological treatments. OA was associated with religions, family history, dietary habits, exercise, blood types, and age groups. Hence, there is a need for a program on the care of dietary habits and physical activities for reducing the progression of OA.