Cartilage interstitial fluid load support in unconfined compression following enzymatic digestion

Interstitial fluid pressurization plays an important role in cartilage biomechanics and is believed to be a primary inechanisin of load support in synovial joints. The objective of this study was to investigate the effects of enzymatic degradation on the interstitial fluid load support mechanism of articular cartilage in unconfined compression. Thirty-seven immature bovine cartilage plugs were tested in unconfined compression before and after enzymatic digestion. The peak fluid load support decreased significantly (p<0.0001) from 84+/-10% to 53+/-19% andfirom 80+/-10% to 46+/-21% after 18-hours digestion with 1.0 u/mg-wet-weight and 0.7 u/mg-wet-iveight of collagenase, respectively. Treatment with 0.1 u/ml of chondroitinose ABC,for 24 hours also significantly reduced the peak fluid load support from 83+/-12% to 48+/-16% (p<0.0001,). The drop in interstitial.fluid load support following enzymatic treatment is believed to result from a decrease in the ratio of tensile to compressive moduli of the solid matrix.