Fig. 5.

Histological appearance and surface chondrocyte viability following monoiodoacetate injection. No difference in the total modified Mankin scores was observed, at any of the study time points, between specimens given a single intra-articular injection of normal saline solution and those given a single intra-articular injection of 0.5% bupivacaine. Injection of 0.6% monoiodoacetate resulted in higher total modified Mankin scores, indicative of increasing degeneration, by four weeks (p < 0.01 compared with those in the saline-solution group), with the highest scores obtained at six months (p < 0.001 compared with those in the saline-solution group). Comparison of the results of the viability imaging and histological assessment of the monoiodoacetate-injected specimens demonstrated consistent and complementary information. A: One week after monoiodoacetate injection, viability assessment showed substantial chondrocyte necrosis despite a normal histological appearance. B: At four weeks, both viability imaging and histological examination showed acellular tissue with empty lacunae and chondrocyte drop-out from superficial to deep zones. C: At twelve weeks, partial cellular repopulation was observed, especially in the superficial zone, with both viability imaging and histological analysis. D: At six months, scattered live and dead cells were seen with viability imaging. Histological examination revealed full-thickness cartilage loss and fibrosis. Scale bars on fluorescent stereomicroscopy images = 40 μm. Scale bars on histological images = 100 μm.