(A,B) Surface and (C,D) overall shear strain, Exz, versus applied lateral displacement (Δx) for normal (NL: ●, ○) and degenerate (DGN: ■, □) cartilage after (A,C) 5 and (B,D) 60 minutes of stress relaxation time (tsr). Samples were tested with phoshate buffered saline (PBS: ○, □) and synovial fluid (SF: ●, ■).