86
Cortisone Directly Damages Rotator Cuff Tendon Cells in Laboratory Study
Full Title
Effects of crystalline glucocorticoid triamcinolone acetonide on cultured human supraspinatus tendon cells.
Summary
This laboratory study investigated the direct effects of triamcinolone acetonide, a crystalline glucocorticoid commonly used in corticosteroid injections, on human rotator cuff tendon cells. The researchers added the steroid to the culture medium of isolated human supraspinatus tendon cells and observed the effects over 2 weeks. The findings were striking. After 2 weeks of exposure, the tendon cells had lost their normal fibroblastic appearance and parallel orientation, showing characteristics of cellular degeneration similar to what is seen in damaged tendons in the body. The production and secretion of collagen type I, which is the primary structural protein in healthy tendons, was strongly reduced. Cell proliferation decreased and cell migration was completely blocked, meaning the tendon cells lost their ability to move and repair damaged tissue. The expression of matrix metalloproteinases, enzymes needed for tissue remodeling, was reduced, while their inhibitors were increased, further impairing the repair process. Additionally, the steroid caused the tendon cells to transform into fat cells and cartilage-like cells rather than maintaining their normal tendon phenotype. These results provide direct cellular evidence that corticosteroid injections may weaken tendons and contribute to the high rate of re-rupture after rotator cuff repair, supporting the recommendation to approach cortisone injections with caution.