Joint Inflammation and Early Degeneration Induced by High-Force Reaching Are Attenuated by Ibuprofen in an Animal Model of Work-Related Musculoskeletal Disorder
Distal radii and carpal bones stained with safranin O and fast green. (a)–(g) are longitudinal sections of paraffin embedded radius, ulna and carpal bones. (a)–(c) Low-power micrographs showing distal radius, scaphoid bones and articular cartilage in (a) NC (normal control), (b) TR (trained control), and (c) HRHF rat (performed the high-repetition high-force task for 12 weeks). (a) also indicates the 4 zones of the articular cartilage assessed in the radius. (d)–(g) Higher-power images showing the distal radii articular cartilage of (d) untreated TR, (e) TR + IBU (trained controls receiving ibuprofen treatment in final 8 weeks), (f) HRHF, and (g) HRHF + IBU rats. (f) demonstrates an HRHF animal with structural changes (surface pannus, arrows), cellular changes (hypocellularity in areas indicated with *), and dramatically reduced proteoglycan staining in the articular cartilage (red-pink safranin O staining). The inset in (f) is a higher-power micrograph from another HRHF rat showing chondrocytes that appear to be proliferating. The inset in (g) shows a higher-power micrograph from area indicated with arrow that also contains proliferating chondrocytes. (h)-(i) Loss of safranin O staining in HRHF articular cartilage was verified in plastic embedded bones that were also cut longitudinally. Radii and scaphoid articular cartilages of (h) HRHF and (i) HRHF + IBU are shown. Scale bars = 50 μm. B: bone, S: scaphoid bone.