Table 1.

Grading scheme for assessment of chondrocyte viability in the mouse knee joint from nitroblue tetrazolium (NBT) staining in viable cells. Maximum possible site score of 5 for the medial and lateral femoral condyles and tibial plateau. Maximum possible total joint score of 20 summed from site scores for each joint.

Grade	Description
0	≥ 95% viable cells in all of plateau or condyle
1	cell death in < ½ plateau or condyle, < ½ depth
2	cell death in < ½ plateau or condyle, ≥ ½ depth
3	cell death in ≥ ½ plateau or condyle, < ½ depth
4	cell death in ≥ ½ plateau or condyle, ≥ ½ depth
5	< 10% viable cells in all of plateau or condyle