Abnormal ground reaction forces lead to a general decline in gait speed in knee osteoarthritis patients

Table 2 Temporospatial and normalised ground reaction results

Variable	Knee OA PWS		Symmetry ratio %	Control PWS		Symmetry ratio %	Knee OA TWS		Symmetry ratio %	Control TWS		Symmetry ratio %
	Affected	Unaffected		Right	Left		Affected	Unaffected		Right	Left
	(n = 24)	(n = 24)		(n = 20)	(n = 20)		(n = 24)	(n = 24)	(n = 24)	(n = 20)	(n = 20)
	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
Speed (m/s)	1.091 (0.14)		NA	1.34 (0.07)		NA	1.372 (0.23)		NA	2.00 (0.20)		NA
Cadence (step/min)	113 (7)		NA	114 (10)		NA	1231,2 (9)		NA	137 (11)		NA
Gait width (cm)	14.6 (4.2)1		NA	11.2 (3.2)		NA	14.21,2 (4.5)		NA	11.2 (3.0)		NA
Weight acceptance (BWN)	1.071 (0.08)	1.121 (0.10)	-4.01 (5.7)	1.18 (0.08)	1.18 (0.07)	0.7 (2.0)	1.182 (0.14)	1.261,2 (0.16)	-5.9 (5.7)1,2	1.55 (0.12)	1.52 (0.12)	2.6 (3.3)
Push-off (BWN)	1.001 (0.06)	1.021 (0.06)	-2.6 (5.2)	1.15 (0.09)	1.16 (0.08)	-1.5 (1.6)	0.951,2 (0.07)	1.001,2 (0.07)	-4.2 (6.0)1,2	1.16 (0.12)	1.17 (0.10)	-0.9 (3.5)
Total impulse (BWN/s)	0.53 (0.05)	0.57 (0.04)	-5.91 (5.6)	0.55 (0.05)	0.55 (0.05)	-0.2 (1.8)	0.491,2 (0.04)	0.531,2 (0.04)	-7.1 (6.2)1,2	0.46 (0.04)	0.46 (0.04)	-0.1 (1.6)
Weight acceptance impulse (BWN/s)	0.1041 (0.008)	0.108 (0.010)	-3.41 (6.3)	0.112 (0.007)	0.112 (0.007)	0.9 (3.1)	0.1132 (0.014)	0.1202 (0.015)	-5.1 (6.6)1,2	0.146 (0.010)	0.142 (0.011)	3.5 (4.2)
Push off impulse (BWN/s)	0.0981 (0.008)	0.0981 (0.011)	0.6 (13.4)	0.111 (0.009)	0.114 (0.008)	-2.9 (2.6)	0.0911,2 (0.008)	0.0981,2(0.007)	-6.6 (8.0)1,2	0.110 (0.011)	0.111 (0.009)	-2.9 (4.7)
Step length (cm)	681 (10)	671 (9)	2.6 (6.5)	79 (6)	78 (5)	1.7 (2.5)	79 (12)2	78 (11)2	2.4 (6.2)	99 (8)	98 (8)	1.0 (1.9)
Step time (s)	0.53 (0.05)	0.54 (0.04)	-1.2 (7.5)	0.53 (0.05)	0.53 (0.04)	0.3 (3.1)	0.481,2 (0.03)	0.502 (0.05)	-4.0 (6.6)1,2	0.44 (.04)	0.44 (0.04)	-0.2 (3.5)
Contact time (s)	0.72 (0.05)	0.731 (0.05)	-2.41 (3.8)	0.68 (0.06)	0.69 (0.06)	-0.3 (1.7)	0.651,2 (0.05)	0.672 (0.07)	-3.4 (3.9)1,2	0.56 (0.05)	0.56 (0.05)	-0.3 (1.5)
Single limb stance time (s)	0.331 (0.04)	0.36 (0.04)	-7.01 (9.3)	0.38 (0.04)	0.38 (0.04)	-0.4 (3.5)	0.321 (0.02)	0.341 (0.03)	-7.5 (8.5)1,2	0.33 (0.04)	0.33 (0.03)	-0.3 (3.1)

The values are indicated as means ± standard deviation;

¹Significant difference between OA group vs control at PWS (P < 0.05);

²Significant difference between OA group vs control at TWS (P < 0.05). PWS: Preferred walking speed; NA: Not available; TWS: Top walking speed; BWN: Body weight normalised; OA: Osteoarthritis.