Intermittent hydrostatic compressive force stimulates exclusively the proteoglycan synthesis of osteoarthritic human cartilage

In paired observations the in vitro proteoglycan turnover was studied of human normal and osteoarthritic cartilage in the absence and presence of intermittent hydrostatic compressive force. Shortly after collection, osteoarthritic cartilage showed a higher proteoglycan synthesis rate than normal cartilage, whereas after culture the reverse was found. Exposure during culture to hydrostatic intermittent compression of a low physiological magnitude enhanced the proteoglycan synthesis rate for osteoarthritic cartilage, whereas normal cartilage was unaffected by this hydrostatic intermittent compression. This enhancing effect was reversible. We conclude that human osteoarthritic cartilage is in vivo synthetically more active than normal cartilage, but loses this increased activity in vitro. Enhanced sensitivity of osteoarthritic cartilage to compressive forces may contribute to the increased proteoglycan synthesis of osteoarthritic cartilage.