The effects of knee brace hinge design and placement on joint mechanics

Walker, Peter S.; Rovick, J. S.; Robertson, Douglas D.

doi:10.1016/0021-9290(88)90135-2

Cited by 151 publications

(120 citation statements)

References 11 publications

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“…The ankle was a revolute joint between the tibia and talus defined by 1 degree of freedom (dorsiflexion/plantarflexion) [26]. The knee had a single degree of freedom (flexion/extension) and used the equations reported by Walker et al [27] and Delp [28] to define the translations and rotations between the femur, tibia and patella as functions of knee flexion angle. The hip was a ball and socket joint with 3 degrees of freedom (flexion/extension, adduction/abduction, and internal/external rotation).…”

Section: Methodsmentioning

confidence: 99%

Fibre operating lengths of human lower limb muscles during walking

Arnold

Delp

2011

Phil. Trans. R. Soc. B

120

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Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle-tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force-length -velocity effects. We found that muscles operate on multiple limbs of the force -length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range.

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Section: Methodsmentioning

confidence: 99%

Fibre operating lengths of human lower limb muscles during walking

Arnold

Delp

2011

Phil. Trans. R. Soc. B

120

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show abstract

“…The ankle is a revolute joint between the tibia and talus, defined by one degree of freedom (dorsiflexion/plantarflexion) (Inman, 1976). The knee has a single degree of freedom (flexion/extension) and uses the equations reported previously (Walker et al, 1988;Delp, 1990) to define the translations and rotations between the femur, tibia and patella as functions of knee flexion angle. The hip is a ball and socket joint with three degrees of freedom (flexion/extension, adduction/abduction and internal/external rotation).…”

Section: Musculoskeletal Modelmentioning

confidence: 99%

How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds

Arnold

Hamner

Seth

et al. 2013

Journal of Experimental Biology

218

219

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SUMMARYThe lengths and velocities of muscle fibers have a dramatic effect on muscle force generation. It is unknown, however, whether the lengths and velocities of lower limb muscle fibers substantially affect the ability of muscles to generate force during walking and running. We examined this issue by developing simulations of muscle-tendon dynamics to calculate the lengths and velocities of muscle fibers from electromyographic recordings of 11 lower limb muscles and kinematic measurements of the hip, knee and ankle made as five subjects walked at speeds of 1.0-1.75ms-1 and ran at speeds of 2.0-5.0ms. We analyzed the simulated fiber lengths, fiber velocities and forces to evaluate the influence of force-length and force-velocity properties on force generation at different walking and running speeds. The simulations revealed that force generation ability (i.e. the force generated per unit of activation) of eight of the 11 muscles was significantly affected by walking or running speed. Soleus force generation ability decreased with increasing walking speed, but the transition from walking to running increased the force generation ability by reducing fiber velocities. Our results demonstrate the influence of soleus muscle architecture on the walk-to-run transition and the effects of muscle-tendon compliance on the plantarflexorsʼ ability to generate ankle moment and power. The study presents data that permit lower limb muscles to be studied in unprecedented detail by relating muscle fiber dynamics and force generation to the mechanical demands of walking and running.Supplementary material available online at

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“…The ankle was a revolute joint between the tibia and talus with one degree of freedom (plantar-flexion and dorsi-flexion) (Inman, 1976;Arnold and Delp, 2011). The knee joint also had one rotational degree of freedom (flexion and extension) with translations and rotations between the femur, patellar and tibia being described by the equations from Walker et al (Walker et al, 1988) and Delp (Delp, 1990). A joint between the thigh and the laboratory coordinate system was created with six degrees of freedom to allow the leg to translate and rotate relative to the laboratory.…”

Section: Musculoskeletal Modelmentioning

confidence: 99%

Musculoskeletal modelling deconstructs the paradoxical effects of elastic ankle exoskeletons on plantar-flexor mechanics & energetics during hopping

Farris

Hicks

Delp

et al. 2014

Journal of Experimental Biology

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Experiments have shown that elastic ankle exoskeletons can be used to reduce ankle joint and plantar-flexor muscle loading when hopping in place and, in turn, reduce metabolic energy consumption. However, recent experimental work has shown that such exoskeletons cause less favourable soleus (SO) muscle-tendon mechanics than is observed during normal hopping, which might limit the capacity of the exoskeleton to reduce energy consumption. To directly link plantar-flexor mechanics and energy consumption when hopping in exoskeletons, we used a musculoskeletal model of the human leg and a model of muscle energetics in simulations of muscle-tendon dynamics during hopping with and without elastic ankle exoskeletons. Simulations were driven by experimental electromyograms, joint kinematics and exoskeleton torque taken from previously published data. The data were from seven males who hopped at 2.5 Hz with and without elastic ankle exoskeletons. The energetics model showed that the total rate of metabolic energy consumption by ankle muscles was not significantly reduced by an ankle exoskeleton. This was despite large reductions in plantar-flexor force production (40-50%). The lack of larger metabolic reductions with exoskeletons was attributed to increases in plantar-flexor muscle fibre velocities and a shift to less favourable muscle fibre lengths during active force production. This limited the capacity for plantarflexors to reduce activation and energy consumption when hopping with exoskeleton assistance.

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The effects of knee brace hinge design and placement on joint mechanics

Cited by 151 publications

References 11 publications

Fibre operating lengths of human lower limb muscles during walking

Fibre operating lengths of human lower limb muscles during walking

How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds

Musculoskeletal modelling deconstructs the paradoxical effects of elastic ankle exoskeletons on plantar-flexor mechanics & energetics during hopping

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