Influence of clodronate, pamidronate, and risedronate on chondrocyte necrosis (A), proliferation (B), and apoptosis (C/D). (A) Percentage of PI+ necrotic cells (10 000 cells were measured). (B) Proliferation of cells (tests were done in quadruplicate). (C) Percentage of annexin V positive, PI- apoptotic cells (10 000 chondrocytes were measured). (D) Percentage of TUNEL positive apoptotic cells (10 000 cells were measured). Dashed lines represent ranges of control cultures. *p <0.05: chondrocytes incubated with bisphosphonates v control cultures.