This study examined the effect of 80 cumulative hours of in vivo cyclical joint loading on the cartilage content of proteoglycans and collagen in the rabbit metacarpophalangeal joint to understand changes due to physical forces. The results showed that loading led to an increase in proteoglycan in the cartilage of all six rabbits, specifically, there was a 46% increase in the cartilage deep zone. The collagen content did not change with loading. Joint loading did not change the superficial and mid zone mean thicknesses. The authors therefore concluded that long-term (80 cumulative hours) cyclic in vivo joint loading stimulates proteoglycan synthesis and stimulation is localized to cartilage regions of high hydrostatic pressure. These data may be useful in developing interventions to prevent overuse injuries or therapies to improve joint function.
Arthritis Research & Therapy, 2006, 8:R147, online