Purpose

In the clinic, cartilage repair is rarely performed in a normal joint. Cartilage damage, either by joint diseases or trauma, often associates with synovitis. Severe synovial inflammation changes the joint environment and is detrimental to articular cartilage. Mild synovitis, however, is often overlooked or missed clinically, on the images and by histology. This study investigated the influence of mild synovitis defined by histology on chondrocyte matrix production.

Methods and Materials

Synovial samples were collected during foot and ankle surgery. A total of 21 patients, including 12 male and 9 female, with an average age of 56 years (27-79) were included in this study. Of each synovial sample, a small portion was used for histology and then scored for the severity of synovitis (score range from 0 to 9). The rest of the synovial sample was digested for isolation of fibroblast-like synoviocytes (FLS). FLS from each donor was cultured and the supernatant of cell cultures was collected.

Chondrocytes were isolated from cadaveric normal knees (n=3) and encapsulated within alginate beads. The supernatant of FLS was added into the chondrocyte culture media at a ratio of 1:1. After cultured for one week, the chondrocytes in alginate beads were collected and extracted proteins for glycosaminoglycan (GAG) and collagen quantification. The synovitis scores of the synovial samples that used for FLS isolation, and GAG and collagen productions (per bead) were analyzed with Spearman’ correlation.

Results

Histologically, synovitis scores of this group of patients were in a range of 0-4. The chondrocyte production of GAG was negatively correlated with the synovitis scores of the synovium, from which FLS were isolated (r=-0.46; p=0.03). Collagen production by chondrocytes after treated with FLS supernatant, however, was not correlated with synovitis score.

Conclusion

Mild synovitis inhibited chondrocyte chondrogenesis, especially GAG production.