Table 4:

Sensitivity of ankle and knee mechanics to component stiffness and speed.

Peak Joint Angles and Moments - Dimensionless							Redimensionalized						Increment Effects
Quantity	Mean ± SD (NS 1.1)	Slope vs. KFore P-val	Coef. KFore*v P	Slope vs. KHind P	Coef. KHind*v P	Slope* vs. Speed v P	Mean ± SD (NS 1.1)	Slope vs. KFore (units)	Coef. KF*v (units)	Slope vs. KHind (units)	Coef. KH*v (units)	Slope* vs. Speed v (units)	FID +15 N/mm (units)	HID +15 N/mm (units)	VID +0.2 m/s (units)
Prosth. Side Ankle‡	−6.84±1.17	-	-	4.5E−2	0.17	−21	−6.84±1.17 (deg)	-	-	5.2E−2 (deg per N/mm)	6.5E−2 (deg per N/mm per m/s)	−6.9 (deg per m/s)	-	1.9 (deg)	−0.80 (deg)
Peak Plantarflexion
		-	-	0.06	0.01	<0.001
Prosth. Side Ankle‡	4.54±0.49	−4.1E−2	−5.7E−2	-	-	3.3	4.54±0.49 (deg)	−4.7E−2 (deg per N/mm)	−2.2E−2 (deg per N/mm per m/s)	-	-	1.1 (deg per m/s)	−1.1 (deg)	-	2.3E−2 (deg)
Peak Dorsiflexion
		0.004	0.14	-	-	0.12
Prosth. Side Knee	−10.4±7	-	-	−0.26	0.42	−28	−10.4±6.7 (deg)	-	-	−0.30 (deg per N/mm)	0.16 (deg per N/mm per m/s)	−9.1 (deg per m/s)	-	−1.9 (deg)	−0.41 (deg)
Peak Flexion (Early Stance)
		-	-	<0.001	0.01	0.002
Prosth Side Knee	2.60±6.79	0.16	−0.23	-	-	14	2.60±6.79 (deg)	0.19 (deg per N/mm)	−8.7E−2 (deg per N/mm per m/s)	-	-	4.4 (deg per m/s)	1.4 (deg)	-	0.10 (deg)
Peak Extension (Mid Stance)
		0.004	0.14	-	-	0.12
Prosth. Side Knee	5.66E−2±3.9E−2	-	-	7.3E−4	−1.2E−3	0.11	44.2±30.3 (N-m)	-	-	0.65 (N-m per N/mm)	−0.36 (N-m per N/mm per m/s)	28 (N-m per m/s)	-	3.9 (N-m)	2.4 (N-m)
Peak Extensor Mom. (Early Stance)
		-	-	0.02	0.16	0.02
Prosth. Side Knee	−5.10E−2±2.4E−2	−9.6E−4	1.6E−3	-	-	−8.8E−2	−39.8±18.7 (N-m)	−0.86 (N-m per N/mm)	0.48 (N-m per N/mm per m/s)	-	-	−23 (N-m per m/s)	−5.0 (N-m)	-	−0.19 (N-m)
Peak Flexor Mom. (Mid Stance)
		0.002	0.06	-	-	0.06
Intact Side Knee	−12.0±3	8.6E−2	−0.22	-	-	−29	−12.0±3.4 (deg)	9.8E−2 (deg per N/mm)	−8.2E−2 (deg per N/mm per m/s)	-	-	−9.5 (deg per m/s)	0.12 (deg)	-	−2.6 (deg)
Peak Flexion (Early Stance)
		0.28	0.32	-	-	0.02
Intact Side Knee	5.70E−2 ±2.0E−2	−6.6E−4	2.1E−3	-	-	0.15	44.5±15.2 (N-m)	−0.59 (N-m per N/mm)	0.61 (N-m per N/mm per m/s)	-	-	38 (N-m per m/s)	1.3 (N-m)	-	13 (N-m)
Peak Extensor Mom. (Early Stance)
		0.18	0.13	-	-	0.052
Prosth. Side Hip	−6.45E−2±2.1E−2	−3.5E−4	6.6E−4	−1.0E−4	−2.4E−4	−0.13	−50.3±16.4 (N-m)	−0.31 (N-m per N/mm)	0.19 (N-m per N/mm per m/s)	−9.2E−2 (N-m per N/mm)	−7.1E−2 (N-m per N/mm per m/s)	−34 (N-m per m/s)	−1.5 (N-m)	−2.5 (N-m)	−6.2 (N-m)
Peak Extensor Mom. (Early Stance)
		0.35	0.52	0.74	0.77	0.004
Prosth. Side Hip	6.66E−2±1.9E−2	6.7E−5	−9.3E−5	9.0E−5	−1.7E−4	0.16	52.0±15.2 (N-m)	6.0E−2 (N-m per N/mm)	−2.7E−2 (N-m per N/mm per m/s)	8.1E−2 (N-m per N/mm)	−5.0E−2 (N-m per N/mm per m/s)	41 (N-m per m/s)	0.46 (N-m)	0.40 (N-m)	7.7 (N-m)
Peak Flexor Mom. (Late Stance)
		0.84	0.92	0.70	0.79	0.003
Intact Side Hip	−9.68E−2±2.4E−2	−2.6E−4	3.1E−4	−1.5E−4	1.1E−4	−0.20	−75.6±18.5 (N-m)	−0.23 (N-m per N/mm)	9.1E−2 (N-m per N/mm per m/s)	−0.13 (N-m per N/mm)	3.4E−2 (N-m per N/mm per m/s)	−50 (N-m per m/s)	−1.9 (N-m)	−1.5 (N-m)	−9.4 (N-m)
Peak Extensor Mom. (Early Stance)
		0.60	0.82	0.63	0.89	<0.001
Intact Side Hip	5.73E−2±3.0E−2	−3.8E−4	5.1E−4	−8.5E−5	5.2E−4	6.8E−2	44.8±23.3	−0.34 (N-m per N/mm)	0.15 (N-m per N/mm per m/s)	−7.7E−2 (N-m per N/mm)	0.15 (N-m per N/mm per m/s)	17 (N-m per m/s)	−2.6 (N-m)	1.4 (N-m)	4.8 (N-m)
Peak Flexor Mom. (Late Stance)
		0.32	0.63	0.77	0.52	0.21

P-values and Slopes vs. Speed are estimated conservatively. P-values are the greater of the P-values of the Speed coefficient in mixed linear regressions with K_Forefoot or K_Hindfoot. Slope values are the lesser of the two Speed coefficients.

^-Indicates statistical test not performed.

^‡Ankle definitions for the prosthetic side are approximate, as the system lacks a true ankle joint.

NS 1.1: Result for Nominal Stiffness condition at 1.1 m·s⁻¹.