Changes in Passive Properties of Hemiplegic nkles With Spastic

Objective: To investigate quantitatively biomechanic changes n the passive properties of hemiplegic spastic ankles. Design: Evaluation of spastic hypertonia by moving the nkle joint slowly between dorsiflexion and plantarflexion exreme positions under controlled joint torque and position. Setting: Institutional research center. Participants: Twenty-four stroke patients with spastic anles and 32 healthy controls. Interventions: Not applicable. Main Outcome Measures: Passive resistance torque at conrolled dorsiflexion and plantarflexion positions, dorsiflexion nd plantarflexion range of motion (ROM) at controlled orques, and quasistatic stiffness and energy loss in dorsiflexion nd plantarflexion. Results: Spastic hypertonic ankles showed significant altertions of the passive properties in plantarflexion (P .041) as ell as in dorsiflexion (P .016) directions. Compared with ealthy controls, spastic ankles showed higher resistance orque (9.51 4.79Nm vs 6.21 3.64Nm, P .016), higher quaistatic stiffness (.54 .19Nm/deg vs .35 .20Nm/deg, .001) at 10° of dorsiflexion, larger normalized dorsiflexion nergy loss (.068 .04J/deg vs .04 .02J/deg, P .037), and ecreased dorsiflexion ROM at 10Nm of resistance torque 10.77° 8.69° vs 20.02° 11.67°, P .014). The resistance orque, ROM, and stiffness of spastic hypertonic ankles in lantarflexion showed similar changes (P .05) to those in orsiflexion. The passive ROM, joint stiffness, and resistance orque at controlled positions correlated with each other and lso correlated with the Modified Ashworth Scale (P .01). Conclusions: Various biomechanic changes in both plantarnd dorsiflexors are associated with spastic hypertonia of hronic stroke patients, and they can be evaluated quantitaively under well-controlled conditions. With simplifications, he various measures in this study can potentially be used to

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