Changes in cartilage and SM
Gross evaluation of cartilage was performed in three studies, which reported that TA or MPA injected in normal joints showed no changes in cartilage appearance (Frisbie et al., 1997; Murray et al., 1998; Frisbie et al., 1998).
Histologic examination of SM was performed in three studies (Frisbie et al., 1997; Frisbie et al., 1998; Todhunter et al., 1998). MPA promoted only mild to no significant changes in cellular infiltrate, proliferation of synovial cells, SM intimal hyperplasia, or fibrous tissues, having only effects on the decrease of SM vascularity (Frisbie et al., 1998; Todhunter et al., 1998). Regarding TA, a significant decrease in inflammatory cell infiltration and intimal cell hyperplasia was found, as was reduced SM subintimal fibrosis (Frisbie et al., 1997).
Histology of articular cartilage was also reported, and no significant changes were found after MPA-injected joints in one study (eight-day follow-up) (Todhunter et al., 1998), while the same corticosteroid worsened histologic scores of articular cartilages with longer follow-up (72 days) (Frisbie et al., 1998). TA effects on cartilage histology were investigated by only one group (Frisbie et al., 1997), which found a significant decrease in pathological changes associated with TA treatment.
Articular PG synthesis and GAG content in cartilage were evaluated. MPA significantly decreased PG and GAG synthesis in normal joints with increases in the synthesis of small proteoglycan monometers (Todhunter et al., 1998), while TA caused a significant increase in GAG synthesis (Frisbie et al., 1997). Total GAG content in cartilage after TA or MPA treatments was not significantly different from controls. However, TA or MPA-treated joints demonstrated a significant loss of SOFG staining in articular cartilage (Frisbie et al., 1997; Frisbie et al., 1998).
MPA injected in normal joints increased collagen and TP synthesis of joint tissues collected postmortem at eight days of follow-up (Todhunter et al., 1998).
Biomechanical properties of normal cartilage that received corticosteroid injections were assessed by Murray et al. (1998), who performed indentation testing postmortem and evaluated the material properties of the cartilage of joints receiving MPA. The authors found that MPA-treated joints were thinner, more compressible, and had less stiff cartilage than controls.