Subchondral Bone Plate Thickening Precedes Chondrocyte Apoptosis and Cartilage Degradation in Spontaneous Animal Models of Osteoarthritis

Table 1

Body weight, microscopic scores, and percentage of caspase-3 of DH and BS2 at four time points.

	DH				BS2
Age (weeks)	10	16	24	30	10	16	24	30
Body weight (g)	601.8 (5.9)^†	845.0 (21.4)^∗†	1083.3 (14.5)^∗†	1071.7 (40.8)^†	498.3 (13.6)^†	729.2 (17.0)^∗†	885.8 (14.5)^∗†	902.5 (18.2)^†
Microscopic score
(i) Medial side	4.2 (1.0)	6.5 (0.9)	9.7 (1.9)	16 (0.8)^∗†	3.2 (0.4)	5.8 (0.7)	9.0 (1.0)	12.5 (1.2)^†
(ii) Lateral side	3.0 (0.4)	5.5 (0.8)	6.2 (0.8)	6.8 (0.9)	3.3 (0.6)	4.3 (0.3)	4.5 (0.4)	5.3 (0.4)
Caspase-3 (%)
(i) Medial side	0.9 (0.3)	2.0 (0.2)	2.8 (0.5)	5.7 (0.6)^∗	1.5 (0.5)	3.0 (0.5)	3.1 (0.5)	4.8 (0.4)
(ii) Lateral side	0.4 (0.1)	1.6 (0.3)	2.5 (0.4)	2.6 (0.4)	1.8 (0.3)	2.2 (0.4)	2.3 (0.5)	3.2 (0.6)

Body weight of DH (𝑛=6) was significantly higher than BS2 (𝑛=6) at each time point (unpaired 𝑡-test, 𝑃<0.01). Over time, both strains had a dramatic increase of body weight between 10 and 24 weeks (one-way ANOVA, 𝑃<0.01). Total microscopic score is always higher in the medial side (vs. lateral side). In the medial side, the microscopic score of DH was significantly greater than BS2 at 30 weeks (Mann-Whitney 𝑈 test, 𝑃<0.05). Over time, only the medial side of DH showed a substantial increase of microscopic score and caspase-3 expression between 24 and 30 weeks (Kruskal-Wallis test, 𝑃<0.01). The data are expressed as mean (SEM); * and † indicate a significant difference between the adjacent time points and strains, respectively.