Kinematic and dynamic gait compensations resulting from knee instability in a rat model of osteoarthritis

Table 2 Correlations between 28-day measures and cartilage lesion size

	OARSI score (medial tibial plateau)	Lesion size (% of cartilage loss)	Lesion size (% of surface affected)	Lesion size (% of depth affected)
Operated limb sensitivity (mech. allodynia)	0.0084	0.0155	0.0054	0.0191
	-0.020 ± 0.059	-0.001 ± 0.003	-0.002 ± 0.006	-0.006 ± 0.012
	0.736	0.646	0.787	0.611
Gait symmetry (spatiotemporal gait)	0.1371	0.1439	0.2851	0.1587
	38.4 ± 25.7	1.74 ± 1.14	5.22 ± 2.21	8.36 ± 5.14
	0.158	0.148	0.034 ^a	0.127
Perc. stance time balance (spatiotemporal gait)	0.3526	0.3443	0.2178	0.3505
	67.2 ± 24.3	2.94 ± 1.08	4.98 ± 2.52	13.6 ± 4.9
	0.017 ^a	0.017 ^a	0.069 ^b	0.016 ^a
Peak vertical force (dynamics, dimensionless)	0.0000	0.0009	0.0003	0.002
	-0.12 ± 14.47	-0.07 ± 0.64	0.09 ± 1.37	-0.14 ± 2.93
	0.994	0.911	0.947	0.963
Vertical impulse (dynamics, dimensionless)	0.1042	0.1023	0.0341	0.0874
	-44.6 ± 34.9	-1.95 ± 1.55	-2.40 ± 1.26	-8.25 ± 7.13
	0.223	0.228	0.494	0.267
Peak propulsive force (dynamics, dimensionless)	0.2016	0.2804	0.3464	0.1757
	-68.6 ± 36.5	-3.58 ± 1.53	-8.49 ± 3.11	-13.0 ± 7.5
	0.082 ^b	0.035 ^a	0.017 ^a	0.106
Propulsive impulse (dynamics, dimensionless)	0.0797	0.1355	0.1758	0.0718
	-137 ± 125	-7.92 ± 5.35	19.2 ± 11.1	-26.3 ± 25.3
	0.290	0.161	0.106	0.316
Serum IL-6 concentration (log transformed)	0.3120	0.5085	0.2694	0.2778
	1.13 ± 0.45	0.064 ± 0.017	0.099 ± 0.043	0.22 ± 0.09
	0.025 ^a	0.002 ^a	0.040 ^a	0.036 ^a

Outcome measures of animal behavior or serum cytokine concentrations that gave evidence of significant (p < 0.05) or near-significant differences among groups (0.05 ≤ p < 0.10) were investigated for correlation to measures of cartilage remodeling and lesion formation. Standard linear regressions were fit to the data set with either OARSI score on the medial tibial plateau or lesion size measured by percentage of cartilage loss, surface loss, or depth loss as the dependent variable (columns). All outcome measures of animal behavior and serum cytokines were obtained at 28 days. Data are presented as goodness of fit (R², top), the slope coefficient (β₁, middle, mean ± standard deviation), and significance of the slope coefficient (p value of β₁, bottom). A significant slope coefficient indicates that the measure of animal behavior or serum cytokine concentration associates with the measure of cartilage remodeling and lesion formation at 28 days. ^aSignificant correlations are presented in bold; ^bnear-significant correlations are in italics.