Fig. 4.

Biotribological analysis of articular cartilage explants. The coefficient of friction (CoF) was measured for freshly isolated immature (7-day-old) and mature (>18 month old) cartilages, and, in vitro cultured growth factor-treated and untreated immature cartilages (see Materials and Methods). The CoF of freshly isolated mature cartilages was significantly higher than their immature counterparts (P < 0.01). The CoF of growth factor-treated explants (ITS-FGF2-TGFβ1) was also significantly higher than untreated (ITS) explants (P < 0.01). The CoF of growth factor-treated cartilage explants increased approximately 3-fold (P < 0.05) following in vitro culture for 21 days compared to freshly isolated immature tissue.