Fig. 4.

Surface chondrocyte viability. No significant loss of surface chondrocyte viability was seen one week after a single intra-articular injection of normal saline solution (A) or 0.5% bupivacaine (B) (p > 0.05 for the comparison between the two groups). In contrast, a single injection of 0.6% monoiodoacetate (MIA) (C) resulted in up to 87% cell death in the femoral condyles and trochlear groove (p < 0.05 compared with the saline-solution group). Viability was assessed with red/green staining and examination with three-dimensional confocal microscopy (living cells stained green [CMFDA] and dead cells stained red [propidium iodide]). The arrows indicate empty lacunae, seen only in the monoiodoacetate group with confocal microscopy. Scale bar = 60 μm.