Relationship between muscle-tendon length, range of motion, and resistance to passive movement in children with normal and increased tone

Abstract

[Purpose] The aim of this study was to quantify the resistance to passive movement by measuring changes in muscle-tendon length and joint range of motion (ROM), before and after applying a standardized 5-kilogram tension force, and to correlate and compare these changes to muscle tone. [Subjects and Methods] Children with cerebral palsy (n=29) and typically developed children (n=12) participated in this observational study. The modified Ashworth scale (MAS) was used to assess tone in the right plantarflexor muscle. An ultrasound-imaging device was used to measure Δmuscle-tendon length in the right medial gastrocnemius muscle, and a goniometer was used to measure right ankle ΔROM. [Results] Compared with the MAS, the results showed that ΔROM had the highest construct validity (convergent and discriminant) followed by Δmuscle-tendon unit length. Therefore, these parameters may be better alternatives to the MAS for the quantitative assessment of resistance to passive movement in patients with increased tone. [Conclusion] This study demonstrated that measuring the change in the passive properties of the muscle-tendon unit, as well as the corresponding change in ROM, might provide better options for assessing resistance to passive movement or muscle tone.

Clasp-Knife Model of Muscle Spasticity for Simulation of Robot-Human Interaction

“…MAS is a standard rating assessment tool to measure the severity of motor impairment level with high interrater [5], [6], specifically for neurological disorder related to spasticity. Though, some researches deny the accuracy of spasticity severity assessment as the feedback resistance and range of movement (ROM) of MAS 1-2 were indistinguishable [7].…”

“…Increase in muscle tone, commonly presented in subject with motor impairment, is generally rooted from muscle spasticity and rigidity upon passive mobilization [6]- [11]. Spasticity is a phenomenon that contributes to the increase in muscle tone proportional to the velocity of passive mobilization, whilst rigidity or resistance contributes to the increase in muscle tone due to hypertonia [3], [7], [9]- [11].…”

“…Throughout the passive mobilization, a spike in moment feedback may occur at a certain angular position. This spike is described as the catch phase [6], [11]- [15]. Additionally, a release phase is presented post catch phase, generating a form of sudden drop in muscle tone before slowly stabilizing as it approaches the maximum functional range of motion (ROM) [6], [9], [14]- [17].…”

“…This spike is described as the catch phase [6], [11]- [15]. Additionally, a release phase is presented post catch phase, generating a form of sudden drop in muscle tone before slowly stabilizing as it approaches the maximum functional range of motion (ROM) [6], [9], [14]- [17]. This phenomenon is known as, claspknife phenomenon, which can be observed during fast passive mobilization for subject with moderate spasticity and it is absent for low or severe spasticity cases [9], [15]- [18].…”

“…A simulation model is necessary to replicate the standard pattern of each MAS and its responses upon passive mobilization. A thorough research has been done to understand the gross kinematics and dynamics of the extremity for different MAS level [6], [11], [12]. However, the simulation model presented in [10], [11] was formulated from kinematic response of induced motion, rather than from the moment response of the muscle.…”